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제11차 강유전체 연합 심포지엄
제24회 유전체물성 심포지엄&
제16회 강유전체 소자/소재 워크숍
초 록 집
2015년 2월 1일~3일
무주리조트 (카니발 컬쳐 팰리스)
주최
강유전체연구회
주관
울산대학교 물리학과 BK21플러스사업단
후원
한국물리학회 응집물질물리 분과, KCMC, 넥스트론, 한맥전자
한국물리학회 응집물질물리 분과
http://www.kps.or.kr
KCMC
http://www.kcmc.biz
넥스트론
http://www.nextron.co.kr
한맥전자
http://hanmacco.com
Sponsors
초청의 말씀
안녕하십니까? 반갑습니다. 매년 새해가 밝아오면 무주에서 개최되는 강유전체 연합 심포지엄이 생각납니다. 올해도 산화물 유전체 분야를 연구하는 재료공학과 물리학 분야 연구자들이 만나서 연구 결과를 발표하고 함께 논의할 수 있는 즐거운 시간이 무주리조트 카니발 컬쳐 앙상블 홀에서 개최합니다. 특히, 올해는 2월 초에 강유전체 연합 심포지엄이 개최되기 때문에 참가하는 학생들과 연구자들이 덕유산 향적봉 행 곤돌라를 타고 보는 아름다운 경치와 함께 향적봉의 눈꽃 축제도 즐길 수 있으며 또한 무주리조트에서 스키를 즐길 수 있기를 기대됩니다. 본 학술대회는 국내 유전체 연구뿐만 아니라 다양한 기능성을 가지는 산화물 분야를 연구하는 물리학, 재료공학 분야의 기초 및 이론 연구와 함께 이 연구를 바탕으로 실질적으로 산업에 응용할 수 있는 응용연구 결과를 함께 논의할 수 있는 소중한 자리이며 또한 서로 자주 만나지 못하였던 연구자들이 서로 우정을 함께할 수 있는 기회가 될 것입니다. 강유전체 연합 심포지엄에 참가하는 모든 참가자들이 2015년 2월 무주리조트를 기억할 수 있는 추억이 남는 즐거운 시간이 되기를 기원합니다.
강유전체 연합 심포지엄 공동위원장 김 일원 (울산대학교) 이 재찬 (성균관대학교)
강유전체 연합 심포지엄 공지사항
- 1 -
심포지엄 조직위원회
■ 자문위원회
권숙일(서울대), 조성호(고려대), 장민수(부산대), 김종진(KAIST), 백성기(포항공대),
박광서(서강대), 정윤희(포항공대), 하조웅(INOSTEK), 박철홍(부산대)
■ 조직위원회
위원장 : 김일원(울산대), 이재찬(성균관대)
위 원 : 장현명(포항공대), 노태원(서울대), 황윤회(부산대), 김상수(창원대),
김명호(창원대), 윤종걸(수원대), 황철성(서울대), 김승현(브라운대)
■ 준비위원회
김일원(울산대), 신영한(울산대), 안창원(울산대), 석해진(울산대),
박효주(울산대 BK21플러스사업단)
■ 논문편집위원회
위원장 : 송태권(창원대)
위 원 : 강보수(한양대), 부상돈(전북대), 양호순(부산대), 이종숙(전남대),
장호원(서울대), 정대용(인하대), 조지영(GIST)
강유전체 연합 심포지엄 공지사항
- 2 -
1. 장소 (학술발표) 무주리조트 카니발 컬쳐 팰리스 지하1층 앙상블 홀(Banquet) 무주리조트 카니발 컬쳐 팰리스 지하1층 심포니 홀(후원업체 홍보) 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
2. 일시
2015. 2. 1.(일) 14:30 ~ 2. 3.(화) 12:003. 강연구분
특별강연 30분 (25분 발표 + 5분 질문)초청강연 20분 (15분 발표 + 5분 질문)학생강연 15분 (12분 발표 + 3분 질문)포스터발표 (1시간 30분)
4. 학회등록
사전등록기한 : 2015. 1. 5.(월) ※ 등록비 : (박사급이상 및 일반) 190,000원 (학생) 140,000원현장등록 : 등록비 외에 추가비용(10,000원) 부담 ※ 등록비 : (박사급이상 및 일반) 200,000원 (학생) 150,000원
5. 초록제출 및 논문투고
초록제출기한 : 2015. 1. 5.(월)Manuscript 제출기한 : 2015. 3. 5.(목)① 투고논문은 강유전체연합심포지엄 논문편집위원회 주관으로 한국물리학회의 JKPS 특별호의
규정에 따라 peer-review 후에 게재 될 예정입니다.② 논문투고 시 논문접수기간내에 JKPS의 본학회 관련 특별호 웹창에 직접 투고하시면 됩니다.③ 논문게재료는 저자부담입니다.④ 2011년 개정된 한국물리학회의 JKPS 특별호 발행지침에 의하여 동일 저자는 공동 저자를
포함하여 최대 2편까지 투고할 수 있습니다.6. Banquet
2015. 2. 2.(월) 오후 6시, 무주리조트 카니발 컬쳐 팰리스 지하1층 심포니 홀※ 동반자 참가비 무료
7. 편한복장으로 참석하십시오.
8. 문 의:
조직위원장 울산대학교 물리학과BK21플러스사업단 무주리조트(숙박 및 시설)울산대학교 김일원 교수전화: 052-259-2323 팩스: 010-2245-2023E-mail: [email protected]
행정직원 : 박효주전화: 052-259-1930 팩스: 010-8638-9655E-mail: [email protected]
전화: 063-320-6801~5 (행사진행 및 답사) 063-320-7617 (티롤호텔) 063-320-7830~4 (가족호텔-콘도)
강유전체 연합 심포지엄 공지사항
- 3 -
무주리조트 찾아오시는 길
(주소: 전북 무주군 설천면 만선로 185)
※ 교통편 : (기차의 경우)
서울역 → 영동역 : 새마을 2시간 30분 소요대전역 → 영동역 : 새마을 30분 소요동대구 → 영동역 : 새마을 1시간 20분 소요부산역 → 영동역 : 새마을 2시간 30분 소요
→ 무주군 (버스 20분)
→ 무주리조트(택시 20분)
(셔틀(시외)버스 50분: 설천면 경유)
※ 참조: 무주리조트 홈페이지 (www.mdysresort.com)
강유전체 연합 심포지엄 공지사항
- 4 -
무주리조트 안내도
(주소: 전북 무주군 설천면 만선로 185)
※ 참조: 무주리조트 홈페이지 (www.mdysresort.com)
■ 무주리조트 도착 후 학회 등록 전 추천 일정
① 무주리조트 도착 → 웰컴 센타에서 숙박 체크인 후 숙소로 이동
② 숙소에서 짐 정리 → 학회장소 이동 (카니발 컬쳐 팰리스)
③ 등록데스크에서 등록 후 학회 참석 (2015. 2. 1. 14:30 등록시작)
(카니발 컬쳐 팰리스 지하1층 앙상블 홀 앞)
강유전체 연합 심포지엄 공지사항
- 5 -
학회장 안내도 (무주리조트 카니발 컬쳐 팰리스 지하1층)
2015년 2월 1일 저녁식사 장소 (만선하우스 3층, 만선한식당)
강유전체 연합 심포지엄 공지사항
- 6 -
논문 투고관련 상세 안내
① 투고논문은 강유전체연합심포지엄 논문편집위원회 주관으로 한국물리학회의 JKPS 특별호의 규정에 따라 peer-review 후에 게재 될 예정입니다. (편집위원장 : 창원대 송태권)
※ 투고논문의 게재승인율은 70%이하 입니다.② 논문게재료는 저자부담입니다.③ 2011년 개정된 한국물리학회의 JKPS 특별호 발행지침에 의하여 동일 저자는 공동 저자를 포함하여 최
대 2편까지 투고할 수 있습니다.
■ 논문 투고 방법은 다음과 같습니다.
물리학회의 JKPS 특별호 웹창에서 직접 투고하여 주십시오.웹투고 창: http://jkps.kps.or.kr/home/journal/article/submission/submission_insert_form_first2009.asp?globalmenu=3&localmenu=2
제출 마감일 : 2015년 3월 5일 (목)
6개 분야로 나누어지며, 웹창 투고시 아래 코드번호 및 포스터 발표번호를 반드시 입력하여 주시기 바랍니다.
코드번호 : 01) Ferroelectric properties
02) Low dimensional and Nano Ferroelectrics
03) Emerging (or Functional) Ferroelectrics
04) Memory and high K Applications
05) Piezoelectric and Electro-optics
06) Energy materials
07) 기타
◾논문원고는 MS Word 또는 TeX으로 작성하시되, 유전체물성연구소 홈페이지 공지사항이나 물리
학회 JKPS 웹투고창에서 반드시 Template을 download 하셔서 양식에 맞추어 작성하여 주십시오.
◾분량 : PDF(출판 format)로 전환하였을 때 4페이지 정도
■ 논문 투고시 PACS번호(Home Page 참조) 및 Keyword는 반드시 알려주셔야 합니다.
■ 원고는 한국물리학회에서 발행하는 물리학 용어집을 참조하시어 작성하여 주시기 바랍니다.
■ 논문은 연구논문, 소논문, 해설 및 논평으로 구분되며, 연구논문, 소논문과 논평은 편집위원회에서 정한
심사과정을 거치고 수정지시와 채택여부는 편집위원회가 결정합니다.
1. 소논문은 논문의 수준이 연구논문과 비슷하고 본문을 절로 나누어 쓰지 않으며 인쇄하여 네 쪽을 넘지
않는 논문입니다.
2. 논평은 이미 게제된 논문에 대한 의견을 담으며 편집위원회의 심사를 통해 그 대상 논문의 저자에게 전
달되고 대상 논문의 저자는 논평에 대한 회답을 할 수 있습니다. 논평과 회답은 초록이 포함되지 않으
며, 각각 인쇄하여 한 쪽으로 제한합니다.
3. 해설은 편집위원회를 거쳐 편집위원장이 의뢰하는 것을 원칙으로 하며 기타의 해설은 편집위원회에서
정한 심사를 거칩니다.
■ 기타 논문작성에 관한 상세한 사항은 한국물리학회 논문투고규정[JKPS]을 참조하시기 바랍니다.
■ 게제된 논문에 대해서는 학회에서 정한 게재료를 지불하여야 합니다. (별쇄본 없음.)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 7 -
19:20 ~ 19:40 I5 Understanding Defects in Ferroelectrics and Their Application
세라믹기술원 이순일
19:40 ~ 20:00 I6 BiVO4 단결정의 Incommensurate Twin Domain Wall에 관한 연구
부산대학교 장민수
20:00 ~ 20:15 O1 Antiferroelectric HfxZr1-xO2 thin films for the energy-related applications
서울대학교 박민혁
20:15 ~ 20:30 O2 Structural properties of strained epitaxial PbVO3 (001) thin films
이화여자대학교 오설희
20:30 ~ 20:45 O3 Oxygen octahedral rotation angle of BiFeO3 films depending on structural modulation of SrRuO3 bottom electrode layer
GIST 이성수
Program
장소 : 카니발 컬쳐 팰리스 지하 1층 앙상블 홀
14:30 ~ 16:00 등록
16:00 ~ 16:10 개회
(좌장 : 전북대학교 부상돈)
16:10 ~ 16:40 P1Revisit of lead-free piezoelectric material systems for practical device applications
브라운대학교 김승현
16:40 ~ 17:00 I1Frequency and temperature dependence of incipient piezoelectricity
UNIST 조욱
17:00 ~ 17:20 I2Lead-free piezoelectric BiFeO3-BaTiO3 thick films
창원대학교 송태권
17:20 ~ 17:40 I3Practical applications of Bi0.5(Na,K)0.5TiO3-based lead-free piezoelectric ceramics
울산대학교 안창원
17:40 ~ 18:00 I4Piezoelectric micromachined ultrasonic transducer (pMUT) by granule spray in vacuum process (GSV)
재료연구소 류정호
18:00 ~ 19:20 저녁식사 (장소: 만선하우스 3층, 만선한식당)
(좌장 : 세종대학교 최택집)
2월 1일 (일요일)2월 1일 (일요일)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 8 -
장소 : 카니발 컬쳐 팰리스 지하 1층 앙상블 홀
08:00 ~ 08:30 조식 (카니발 컬쳐 팰리스 지하1층 다과테이블)
(좌장 : 전남대학교 이종숙)
08:30 ~ 09:00 P2Searching for new frontiers in ferroelectric researches
서울대학교 노태원
09:00 ~ 09:20 I7In-situ TEM observation of ferroelectric domain switching
POSTECH 오상호
09:20 ~ 09:40 I8Functionality of domain walls in BiFeO3
건국대학교 이지혜
09:40 ~ 09:55 O4Creep-free ac dynamics in epitaxial ferroelectric BiFeO3 films
서울대학교 신영재
09:55 ~ 10:10 O5Reversible three out-of-plane ferroelectric states in BiFeO3 thin films
KAIST 이진홍
10:10 ~ 10:30 휴식
(좌장 : 인하대학교 정종훈)
10:30 ~ 10:50 I9Strain effect on the visible emission in ferroelectric nanotube: template and wall-thickness effect
숭실대학교 이윤상
10:50 ~ 11:10 I10First-prinsiple study on the piezoelectric properties of hydrofluorinated graphene multilayers
울산대학교 김혜정
11:10 ~ 11:25 O6Freestanding ZnO nanorod/graphene/ZnO nanorod epitaxial double heterostructure for improving piezoelectric nanogenerator
부산대학교 신동명
11:25 ~ 11:40 O7Applications of transmission line impedance models in materials research focusing in energy devices
전남대학교 신의철
11:40 ~ 11:55 O8Low operation voltage of ferroelectric polymer devices induced by X-ray irradiation-mediated atructural transition
GIST 이현준
11:55 ~ 12:10 O9Why no ferroelectricity in polar piezoelectric GaFeO3?
POSTECH 송승우
2월 1일 (일요일)2월 2일 (월요일)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 9 -
12:10 ~ 16:30 자유시간
16:30 ~ 18:00 Poster Sesstion (P-001 ~ P-114), 학생 포스터 발표 심사진행
18:00 ~ 20:30 Banquet (장소: 카니발 컬쳐 팰리스 지하 1층 심포니 홀)
(사회: 부산대학교 황윤회)
08:30 ~ 09:00 조식
09:00 ~ 12:00 강유전체 연구회 회의
12:00 폐회
2월 1일 (일요일)2월 3일 (화요일)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 10 -
Poster Session
2015년 2월 2일(월) 16:30 ~ 18:00 (P-001 ~ P-114)
무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-001
Dependence of electrical properties of Sol–gel derived PZT thick films on crystalline
orientation
V. Annapu Reddy*, Jong-Jin Choi, Jungho Ryu
(재료연구소)
P-002
Enhanced magnetoelectric coupling in a PZT/Metglas bilayer thick film composite
Haribabu Palneedi1,2, Deepam Maurya3, Shashank Priya3, Suk-Joong L. Kang1*,
Si-Young Choi2, and Jungho Ryu2
(1.KAIST, 2.재료연구소, 3.버지니아 공과대학)
P-003
Enhanced polarization of hard polar phases in a heterphase polycrystalline
G. Y. Kim1, S. D. Kim1, Y. M. Rhyim1, S. Y. Yoon2 and S. Y. Choi1*
(1.재료연구소, 2.부산대)
P-004
Temperature Dependance of Magnetic Domains in Co2Z-type Hexaferrite: TEM Studies by
In-situ Heating and Lorentz Microscopy Methods
Sung-Dae Kim1*, Tae-Won Lim1,2, Gi-Yeop Kim1,3, Kee Hoon Kim4 and Si-Young Choi1
(1.재료연구소, 2.경남대, 3.부산대, 4.서울대)
P-005
Electric and structural properties in polar/non-polar multilayers.
Kil-Dong Sung1*, Gi-Yeop Kim1,2, and Si-Young Choi1
(1.재료연구소, 2.부산대)
P-006
Cationic ordeirng and magnetic properties of Re-based double perovskite oxides
T. W. Lim1,2, S. D. Kim1, K. D. Sung1, H. J. Jean3, J. D. Yun2, M. S. Choi1
and S. Y. Choi1*
(1.재료연구소, 2.경남대, 3.부산대)
P-007
Growth and Characterization of LaAlO3 Thin Films Grown by off-axis RF Sputtering
D. H. Kim, C. W W. Bark*
(가천대)
P-008
Synthesis and characterization of UV treated bismuth titnate doped TiO2
M. G. Song, and C W bark*
(가천대)
P-009
Effect of Yb doping on the multiferroic properties of epitaxial BiFeO3 thin films
Yoonho Ahn,1 Jeongdae Seo,1 Jong Yeog Son1,* and Joonkyung Jang2,*
(1.경희대, 2.부산대)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 11 -
P-010
Source Concentration and Temperature dependence of Microstructure and Properties of ZnO
thin films deposited by MOCVD using Ultrasonic Nebulization
C. H. Lee*, M. S Choi
(계명대)
P-011
Effect of Bi(Ni0.5Ti0.5)O3 doping on structural and piezoelectric properties of BiFeO3-BaTiO3
ceramics
I. J. Hwang1, D. Do1*, M. H. Lee2, J. S. Park2, D. J. Kim2, T. K. Song2, M.-H. Kim2,
S. W. Kim2 and W.-J. Kim2
(1.계명대, 2.창원대)
P-012
Growth of graphene using pulsed laser deposition technique with in-situ monitoring by
reflection high energy electron diffraction
J. H. Kwak, H. J. Lee, S. S. Lee, G. Anoop, and Ji Young. Jo*
(GIST)
P-013
Synthesis of catalytic LaMnO3+d nanoparticles by laser ablation in solution
W. S. Kim, G. Anoop, H. J. Lee, S. S. Lee, J. H. Kwak, H. J. Lee, and Ji Young Jo*
(GIST)
P-014
Superlattice of FeSexTe1-x superconductor thin films
S. Seo1, J. H. Kang2, C. B. Eom2, and S. Lee1*
(1.GIST, 2.University of Wisconsin-Madison)
P-015
Band gap tunability of Fe, Co doped Bismuth Lanthanum Titanate thin films deposited by
PLD
H. An1, J. Y. Han2, C. W. Bark2, S. Lee1*
(1.GIST, 2.가천대)
P-016
BaZrO3 incorporated Ba(Fe,Co)2As2 multilayer epitaxial thin films
J. Lee1, J. D. Weiss2, J. Jiang2, E. E. Hellstrom2, and S. Lee1*
(1.GIST, 2.Florida State Universit)
P-017
Thermoelectric properties of organic multilayers
Hye Jeong Lee1, Hyeon Jun Lee1, Yong Jae Kim2, Eun Ji Lee2, Jae Yoo Choi3,
Hee Suk Kim3, and Ji Young Jo1*
(1.GIST, 2.경남대, 3.한국과학기술연구원)
P-018
Ferroelectric Properties of PMT-PT ceramics modified with Bi2O3
G. B. Kim*
(단국대)
P-019
Thermal Annealing Effects of Zn1-xLixO Grwon by So-Gel Method
J. W. Hyun*, G. B. Kim, J. H. Lee
(단국대)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 12 -
P-020
Admittance Spectroscopy of the PbSc1/2Nb1/2O3 Polycrystalline Relaxor
Y. J. Kim*
(단국대)
P-021
Effect of sintering temperature on electrical properties of Lead-free (K0.5Na0.5)0.75Ag0.25NbO3
ceramics
J. D. Byun, Y. J. Kim and J. W. Hyun*
(단국대)
P-022
Highly Durable Ti-mesh Based Triboelectric Nanogenerator for Self-Powered Device
Application
Ermias Libnedengel Tsege1, Dong-Myeong Shin1, Seunghun Lee2, Hyung-Kook Kim1,*
and Yoon Hwae Hwang1,*
(1.부산대, 2.고려대)
P-023
Thermal Conductivity and Interfacial Thermal Resistance of Gd2Zr2O7 Thin Films
J. H. Kwak , J. G. Kang, and H. S. Yang*
(부산대)
P-024
Graphene oxide-stimulated myogenic differentiation of C2C12 skeletal myoblasts
J. H. Lee, M. J. Kim, Y. C. Shin, S. E. Kim, J. S. Kim, J. H. Park and D. -W. Han*
(부산대)
P-025
Structures and optical studies of the rare-earth-doped Ca5(PO4)3Cl powders
김영경1, 양호순1, 홍경수2
(1.부산대, 2.한국기초과학지원연구원)
P-026
Structural phase transition and polarization analysis of non-centrosymmetry phases in BiOIO3
Nayoung Song and Bog G. Kim*
(부산대)
P-027
First Principles Study on the Structural Stability between TiO2 Rutile and TiO2 Anatase
K. S. Choi* and C. H. Park
(부산대)
P-028
Microwave Tunable Properties of CPW Phase Shifter Based on Barium Stannate Titanate
Thin Films
H. C. Ryu1* and S. J. Lee2
(1.삼육대, 2.한국전자통신연구원)
P-029
One-dimensional hematite nanostructures for photoelectrochemical water splitting
Do Hong Kim1,2, Young-Seok Shim1, Moon Cheon Woo1, Koo Tak Hong1,
Jong-Myeong Jeon1, Yeon Hoo Kim1, Ki Chang Kwon1, Jun Min Suh1,
Dinsefa Mensur1, Jong-Heun Lee2, and Ho Won Jang1*
(1.서울대, 2.고려대)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 13 -
P-030
A New Approach to the Negative Capacitance of Ferroelectric Thin Films
Y. J. Kim1*, Y. H. Park1, Y. H. Lee1, H. J. Kim1, W. Jeon1, T. Moon1, K. D. Kim1,
D. S. Jeong2, H. Yamada3, and C. S. Hwang1
(1.서울대, 2.한국과학기술연구원, 3.JST-PRESTO;AIST)
P-031
Study on the wake-up phenomenon of ferroelectric Hf0.5Zr0.5O2 thin films by polarization
switching and discharge behavior
H. J. Kim*, M. H. Park, Y. J. Kim, T. Moon, K. D. Kim, Y. H. Lee, and C. S. Hwang
(서울대)
P-032
Photoactivity of Nanocrystalline Bismuth Vanadate Photoanodes Prepared by Anodic
Electrodeposition
Migyoung Lee*, Hoon Kee Park, Seonyong Lee, Seokhoon Choi, Jaeho Choi,
Byung Suh Han, Boreum Lee, Seo Yun Park, H. W. Jang
(서울대)
P-033
Switchable all oxide capacitor with nm-thick ferroelectric BaTiO3: a direct evidence for
ferroelectric critical thickness
P. Murugavel1,3*, S. R. Lee1,2⧧, Y. J. Shin1,2, Daniel Sando1,2, J.-G. Yoon4
and T. W. Noh1,2
(1.기초과학연구원, 2.서울대 3.Indian Institute of Technology Madras 4.수원대)
P-034
X-ray radiation effects in P(VDF-TrFE) using atomic force microscopy
Owoong Kwon1, Hyeon Jun Lee2, Hosung Seo1, Hye Jeong Lee2, Ji Young Jo2,
Yunseok Kim1*
(1.성균관대, 2.GIST)
P-035
Reaction Pathway of Steam Methane Reforming on Ni3M (111) (M = Rh, Ru) Surface: A
DFT Study
Hanmi Kim, Jaichan Lee*
(성균관대)
P-036
Frequency dependent electromechanical response for distinguishing different origins in
strain-based atomic force microscopy
Daehee Seol, Seongjae Park and Yunseok Kim*
(성균관대)
P-037
Homoepitaxial single- and poly-crystalline SrTiO3 thin films
Sungmin Woo1, Hoidong Jeong1, Sang A Lee1, Hosung Seo1, Morgane Lacotte2,
Adrian David2, Hyun You Kim3, Wilfrid Prellier2, Yunseok Kim1, WooSeokChoi1*
(1.성균관대, 2.Normandie Universite, 3.충남대)
P-038
Crystal and electronic structure of homoepitaxial SrTiO3 thin films with elemental vacancies
Sang A Lee, Hoidong Jeong, Sung Min Woo, Jae-Yeol Hwang, Seul Ki Roh,
Jung Seek Hwang, Sung Wng Kim, and Woo Seok Choi*
(성균관대)
P-039Enhanced Photon Absorption of Titanate Nanosheets
Bongwook Chung1, Minoru Osada2 and Jaichan Lee1*
(1.성균관대, 2.NIMS;MANA)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 14 -
P-040
Tailoring of Electron-Phonon Coupling in Artificially Designed Superlattice
Minsu Choi, Taejun Hwang, Jiwon Seo, Tran Min Dao and Jaichan Lee*
(성균관대)
P-041
Surface sulfurization of laser-ablated WO3 films for solar water splitting
Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee and Taekjib Choi*
(세종대)
P-042
Enhanced Photoelectrochemical Properties of Oxide Semiconductor Heterostructures
Wooyoung Choi, Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee, and Taekjib Choi*
(세종대)
P-043
Non-volatile resistive switching effect of LaAlO3/SrTiO3 heterostructures
Sungmoon Hwang1, Yeonsoo Kim2, Baeho Park2 Taekjib Choi1*
(1.세종대, 2.건국대)
P-044
Resistive switching in TiO-SiO composite films after soft breakdown
Tae-Sup Yoo, Chan-Goo Park, and Jong-Gul Yoon*
(수원대)
P-045
Pt-nanoparticle imbedded ZnO-based thin films for ultra-violet photodetector
Khalkhulin Daniil, Seong-Hoon Kim, Hyuna Im, and Jong-Gul Yoon*
(수원대)
P-046
Piezoelectric Properties of Bismuth Copper-based Lead-free Ceramics
Achiri Tange, Hee Sung Kim, Chang Won Ahn and Ill Won Kim*
(울산대)
P-047
Electric Field-Induced Strain of Lead-Free Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 Ceramics Modified
with BaZrO3
T. H. Dinh, J. K. Kang, C. H. Lee, C. D. Park, Y. H. Hong and J. S. Lee*
(울산대)
P-048
Polar discontinuities and piezoelectric properties of honeycomb lattices
Mohammad Noor-A-Alam and Young-Han Shin*
(울산대)
P-049
Precise measurement of piezoelectric coefficients of PVDF-TrFE films using a Laser
Doppler Vibrometer
Bong Chan Park#, Amir Ullah, Chang Won Ahn and Ill Won Kim*
(울산대)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 15 -
P-050
CH3NH3PbI3-xClx 두께 변화에 따른 페로브스카이트 태양전지 효율
Sujung Park, and Shinuk Cho*
(울산대)
P-051
Self-polarization in the a lead-free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric thin films on
Nb:SrTiO3 substrate from interfacial strain relaxation
Hae Jin Seog1, Chang Won Ahn1, Song A Chae1, Kwang-Eun Kim2, Chan-Ho Yang2,
Tae Yeong Koo3 and Ill Won Kim1*
(1.울산대, 2.KAIST, 3.포항가속기연구소)
P-052
First-principles study of the effect of oxygen vacancies around the 180° ferroelectric
domain walls of tetragonal PbTiO3
Hoe-Cheol Song, and Young-Han Shin*
(울산대)
P-053
Piezoelectric P(VDF-TrFE) Thin Film Power Generators on Paper Substrates for Wearable
Device Applications
Sung Sik Won1,2, Nicholas Mostovych2, Angus I. Kingon2, Ill Won Kim1*
and Seung-Hyun Kim2#
(1.울산대, 2.Brown University)
P-054
Low Temperature Sintering of 0.74(Bi0.5Na0.5TiO3)-0.26SrTiO3 Ceramics by Adding CuO as
a Sintering Aid
D. H. Lee, J. K. Kang, T. H. Hinh and J. S. Lee*
(울산대)
P-055
Properties of [0.98{Bi1/2(Na0.78K0.22)1/2TiO3}-0.02LaFeO3]-Bi1/2(Na0.82K0.18)1/2TiO3 Lead-Free
Piezoceramic Composites
C. H. Hong1*, H. S. Han2, J. S. Lee3, W. Jo1
(1.UNIST, 2.Technische Universität Darmstadt, 3.울산대)
P-056
Investigation of the local work function distribution and resistance change of VO2/Al2O3 and
VO2/TiO2 thin films spanning the metal-insulator transition
Ahrum Sohn1, Teruo Kanki2, Hyun-Tak Kim3,4, and Dong-Wook Kim1,*
(1.이화여대, 2.Osaka University, 3.한국전자통신연구원, 4.UST)
P-057
Structural and electrical properties of epitaxial PbTiO3 thin films on conducting LaNiO3
grown by laser ablation
H. J. Jin, S. H. Oh, and W. Jo*
(이화여대)
P-058
Dielectric properties of PIN-PMN-PT Films Prepared by Aerosol-Deposition Method
S. B. Kang1, Y. M. Kong2, J. H. Ryu3, L. Wang4 and D. Y. Jeong1*
(1.인하대, 2.울산대, 3.재료연구소, 4.Xi’an Jiaotong University)
P-059
A 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 based pyroelectric generator and temperature sensor
Young Joon Ko, Byung Kil Yun, and Jong Hoon Jung
(인하대)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 16 -
P-060
Room-temperature hydrogen gas sensing properties of Co3O4/Nb2O5 composite nanoparticles
S. H. Kim, S. H. Park, H. J. Kheel and C. M. Lee*
(인하대)
P-061
Fabrication, structure and gas sensing properties of Pt- functionalized ZnS nanowires
S. Park, S. Kim, G. Sun and C. Lee*
(인하대)
P-062
Electric polarization and diode-like conduction in hydrothermally grown BiFeO3 thin films
T. K. Lee and J. H. Jung
(인하대)
P-063
Electrical Properties of Polyvinyldene-fluoride-ZnO Modified CNT Nanocomposite Film by
Spray coating
J. H. Lim1, J. k. Lee1, H. J. Kim1, I. J. No1, Y. M. Kong2, and D. Y. Jeong1*
(1.인하대, 2.울산대)
P-064
Synthesis of Homogeneous Nanocrystalline LiFePO4 by Two Step Polyol Process and Their
Performance
S. J. Kim, J. J. Song, J. H. Gim, B. J. Paul, J. G. Jo, W. G. Park, Y. P. Oh, S. K. Nam,
and J. K. Kim*
(전남대)
P-065
Nanostructure carbon coated LiFePO4 by a scalable polyol combustion synthetic strategy
J. H. Gim1, V. Mathew1, S. H. Kim1, D. Y. Kim1, Y. E. Kim1, D. C. Ahn2, W. B. Im1,
Y. K. Paik3 and J. Kim1,*
(1.전남대, 2.포항가속기연구소, 3.한국기초과학지원연구원)
P-066
Impedance Spectroscopy on Multiferroic Bi0.5K0.5TiO3-BiFeO3
Su-Hyun Moon, Ji-Hoon Kim, Eui-Chol Shin, John Gerard Fisher and Jong-Sook Lee*
(전남대)
P-067
Understanding electrochemical reaction of orthorhombic NCO using in-situ X-ray Diffraction
for sodium ion batteries
J. J. Song, J. H. Gim, S. J. Kim, J. G. Jo, S. H. Park, P. T. Duong, J. H. Yang, J. Lee,
and J. K. Kim,*
(전남대)
P-068
In-depth Electrical characterization of Dye-Sensitized Solar Cells by Impedance Spectroscopy
Method
Dang-Thanh Nguyen, Seok Jae Kim, Eui-Chol Shin, Soon-Hyung Kang, Eun-Mi Han
and Jong-Sook Lee*
(전남대)
P-069
Moving boundary diffusion mechanism in non-monotonic hydration/dehydration AC
relaxation in protonic conducting perovskites
Dong-Chun Cho, Gye-Rok Kim, Eui-Chol Shin and Jong-Sook Lee*
(전남대)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 17 -
P-070
Polyol-mediated solvothermal synthesis and improved electrochemical performance of novel
K-doped Co3O4 as negative electrode for secondary lithium-ion batteries
J. G. Jo, Z. Xiu, M. H. Alfaruqi, V. T. Trang, S. G. Lee, and J. K. Kim*
(전남대)
P-071
졸-겔 방법 및 다공성 알루미나 멤브레인을 이용하여 제작된 Pb(Zr0.52Ti0.48)O3나노튜브
어레이의 압전 특성 연구
김병훈, 양선아, 강신욱, 부상돈*
(전북대)
P-072
CaBi4Ti4O15세라믹스의 전기적 특성에 감마선 조사가 미치는 영향
전도현, 최기쁨, 조삼연, 부상돈*
(전북대)
P-073
Carbon-nanotube-encapsuled Ferroelectrics Nanocrystals for Energy Harvesting by Mechanical
Movements
J. K. Han1, D. H. Jeon1, S. Y. Cho1, S. W. Kang1, S. A Yang1, K. Y. Choi2, E. J. Ra3,
J. S. Lim3, and S. D. Bu1*
(1.전북대, 2.서울대, 3.한국화학연구원)
P-074
The use of (NH4)2WS4 precursor as hole extraction layer in organic photovoltaic cells
Quyet Van Le, Thang Phan Nguyen, Soo Young Kim*
(중앙대)
P-075
Facile route for the synthesis of MoS2 and WS2 nano dots
Thang Phan Nguyen, Kyoung Soon Choi, and Soo Young Kim*
(중앙대)
P-076
Piezoelectric and Electrical Properties of Li-doped (Bi0.5Na0.5)TiO3-PVDF Composite for
Energy Harvesting
Joong-Hyeon Ahn and Jung-Hyuk Koh*
(중앙대)
P-077
Enhanced Piezoelectric and Dielectric Properties of Na0.5K0.5NbO3-CaCu3Ti4O12 Lead-Free
Composite
Jae-Hoon Ji and Jung-Hyuk Koh*
(중앙대)
P-078
Temperature Dependent Ferroelectric and Field-Induced Strain Response of Nb-doped
BNBT-SZ Lead-free Piezoelectric Ceramics
Adnan Maqbool, Ali Hussain, Jamil Ur Rahman, Rizwan Ahmed Malik, Tae Kwon Song,
Won-Jeong Kim, and Myong-Ho Kim*
(창원대)
P-079
Compositional-induced structural and non-ergodic to ergodic relaxor transition in lead-free
Ta-doped Bi0.5(Na0.84K0.16)0.5TiO3–SrTiO3 ceramics
Rizwan Ahmed Malik1, Ali Hussain1, Arif Zaman2, Tae Kwon Song1, Won-Jeong Kim1
and Myong-Ho Kim1,*
(1.창원대, 2.Abdul Wali Khan University)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 18 -
P-080
새로운 비납계 BiFeO3-BaTiO3 압전 재료의 물성 평가
D. J. Kim1, M. H. Lee1, J. S. Park1, M.-H. Kim1, S. S. Kim1, D. Do2, H. Y. Lee3,
and T. K. Song1*
(1.창원대, 2.계명대, 3.Ceracomp Co., Ltd)
P-081
Structural, electrical and multiferroic properties of chemical solution deposited Aurivillius
Bi7Fe3Ti3-xNbxO21 thin films
C. M. Raghavan, J. W. Kim, J. Y. Choi, M. J. Lee and S. S. Kim*
(창원대)
P-082
Study on the new type of piezoelectric actuator utilizing smooth impact drive mechanism
M. H. Park1, H. H. Jeong2, S. S. Jeong3 and T. G. Park3*
(1.국방기술품질원, 2.SAMJEON CO., LTD, 3.창원대)
P-083
Ferroelectric properties of (1-x)BiFeO3-xBaTiO3 solid-solution thin films
J. S. Park, M. H. Lee, S. W. Kim, D. J. Kim, S. J. Han, S. Kumar, M-H. Kim, W-J. Kim,
and T. K. Song*
(창원대)
P-084
Na0.5Bi0.5TiO3-BaZrO3 textured ceramics prepared by reactive templated grain growth method
Ali Hussain, Jamil Ur Rahman, Adnan Maqbool, Rizwan Ahmed Malik, Tae-Kwon Song,
Won-Jeong Kim, and Myong-Ho Kim*
(창원대)
P-085
New high Curie temperature lead-free piezoceramics in BiFeO3-BaTiO3 solid solution
이명환1, 김다정1, 박진수1, 김명호1, 송태권1† , 김상욱1, 김원정1, 김상수1, 장기완1, 도달현2,
정일경3
(1.창원대, 2.계명대, 3.부산대 유전체물성연구소)
P-086
Study on the output characteristics of the lambda type ultrasonic motor depending on the
polarization direction of the piezoelectric ceramic
S. K. Cheon1, S. S. Jeong1, Y. W. Ha1, B. H. Lee1, H. I. Jun2, T. G. Park1*
(1.창원대, 2.Mattron corp)
P-087
Structure and electrical properties of rare-earth substituted K0.5Bi4.5Ti4O15 thin films prepared
by chemical solution deposition
J. Y. Choi, J. W. Kim, C. M. Raghavan, M. J. Lee and S. S. Kim*
(창원대)
P-088
Optical ad electrical properties of band-gap controlled Ge doped ZnO1-xSx thin films
S. J. Han1, S. W. Kim1, M. H. Lee1, J. S. Park1, D. J. Kim1, D. Do2, M. H. Kim1,
T. K. Song1, and W. J. Kim1*
(1창원대, 2계명대)
P-089
Metal-insulator transition in NdNiO3 by hydrogen doping
C. D Oh*, S. Y. Heo, H. M. Jang and J. W Son
(POSTECH)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 19 -
P-090
Hydrogen-bonding effects in organohalide-perovskite-based solar cells: first-principles study
June Ho Lee* and Hyun Myung Jang
(POSTECH)
P-091
Modulated Spin Structure responsible for the Magnetic-Field-Induced Polarization Switching
in Multiferroic TbMn2O5
Jung-Hoon Lee, Seungwoo Song and Hyun Myung Jang*
(POSTECH)
P-092
Rapid Thermal Heating Effects on the Zn0.85Mg0.15O:Ga Thin Films
Byeong-Eog Jun*, Sunwoo Kim, Sangwoo Kim, Seongmin Lee, Jimin Koo,
and Jong Rim Lee
(KAIST)
P-093
Preparations of the Ba1-xEuxTiO3 Ceramics in the Nitrogen Gas Ambient
Byeong-Eog Jun*, Minki Kim, Seung-Min Oh and Jong Rim Lee
(KAIST)
P-094
Optical Characterization of Semiconductor ZnxCu1-xO Nanoparticles Prepared by
Hydrothermal method
J. P. Kim*, S. H. Jung, J. H. Kim, M. G. Ha, J. S. Bae, T. E. Hong, E. D. Jeong,
K. S. Hong, J. S. Jin
(한국기초과학지원연구원)
P-095
Direct Adhesion of Polyphenylenesulfide Resin and Polymeric Film on Copper by Surface
Modification
Eun Hyuk Chung1, F. Nawaz Khan1,2, Tae Eun Hong1, Jong Pil Kim1, Jong-Seong Bae1,
and Euh Duck Jeong1*
(1.한국기초과학지원연구원, 2.VIT University)
P-096
Glass formation conditions and photophysical properties of the samarium-containing binary
and ternary tellurium glass ceramics
강보배1, 하명규1, 김현규1, 양호순2, 홍경수1
(1.한국기초과학지원연구원, 2.부산대)
P-097
BaTiO3 나노 입자의 소성 시 첨가제에 따른 미세구조 및 유전특성
The microstructure and the dielectric properties with additives in the sintering of BaTiO3
nano particle
Jae Won Kang1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Dae Yong Jeong2
(1.한국세라믹기술원, 2.인하대)
P-098
4상 혼합 유전체 기판 소재의 상 분율에 따른 미세구조와 기계적 강도
Chang Hyun Lee1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Hyo Tae Kim1, Sahn Nahm2
(1.한국세라믹기술원, 2.고려대학교)
P-099
ZnO-B2O3계 glass 첨가에 따른 Ca[Li1/3Nb2/3)0.8Ti0.2]O3-δ 세라믹스의 마이크로파 유전특성
Chi-Seung In1,2, Dong-Hun Yeo1*, Hyo-Soon Shin1, Sahn Nahm2
(1.한국세라믹기술원, 2.고려대)
제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트
- 20 -
P-100
Influence of some metal electrodes on dielectric properties of PTC ceramic thermistor
Myoung Pyo Chun*
(한국세라믹기술원)
P-101
High Performance Lead Free Piezoelectric Ceramic Composite
S. M. Jang* and S. J. Jeong
(한국전기연구원)
P-102
The study of thermoelectric properties in cobalt silicide/silicon thin film thermoelectric
devices
Soojung Kim1,2, Hyundal Jung1, Wonchul Choi1,3, Junsoo Kim1, Dongsuk Jun1,
Taehyoung Zyung1,2 Taekwang Kim1, Eun-su Nam1 and Seungen Moon11,*
(1.한국전자통신연구원, 2.UST, 3.KAIST)
P-103
Thermoelectric properties of sputtered silicon membrane in vertical direction
Junsoo Kim1, Wonchul Choi1,3, Soojung Kim1,2, Taekwang Kim1, Hyundal Jung1,
Dongsuk Jun1, Taehyoung Zyung1,2, Seung-Min Lee4, Eun-su Nam1 and Seungen Moon1,*
(1.한국전자통신연구원, 2.UST, 3.KAIST, 4.Hanbeam co,)
P-104
Low Power Consumption and High Sensitive Micro Alcohol Gas Sensor based on
Co-planar Micro-heater and Screen Printing Technique
S. E. Moon1*, T. K. Kim1, J. S. Kim1, W. C. Choi1, B. H. Park2, J. C. Kim2, J. J. Jung3
and D. J. Yoo3
(1.한국전자통신연구원, 2.건국대, 3.Sentech Korea)
P-105
Fabrication and Field Effect Electronic Properties of Amorphous ZnO-SnO2 Superlattice Thin
Films
Su-Jae Lee, Chi-Sun Hwang, Jae-Eun Pi, and Kyoung-Ik Cho
(한국전자통신연구원)
P-106
ALD 방법으로 증착된 Al2O3 박막의 열전도도 측정
Wonchul Choi1,3, Soojung Kim1,2, Hyundal Jung1, Junsoo Kim1, Dongsuk Jun1,
Taehyoung Zyung1,2, Eunsoo Nam1, Seungmin Lee4, and Seungen Moon1,*
(1.한국전자통신연구원, 2.UST, 3.KAIST, 4.Hanbeam co,)
P-107
고압 브릴루앙 산란을 이용한 Polydimethylsiloxane의 고압특성 분석
신선협1, 고재현1*, 고영호2, 김광주2
(1.한림대, 2.국방과학연구소)
P-108
Phase Transition Behaviors of Lead-Free (NaBi)TiO-BaTiO Single Crystals Studied
by Inelastic Light Scattering Spectroscopy
Byoung Wan Lee1, Jun Ho Ryeom1, Jae-Hyeon Ko1, Xiaobing Li2 and Haosu Luo2
(1.한림대, 2.Shanghai Institute of Ceramics)
P-109
Phase transition behaviors of PbZr0.8Ti0.2O3 single crystals as revealed by elastic anomalies
and central peaks
Min-Seok Jeong1, Jae-Hyeon Ko1*, Seiji Kojima2, Alexei A. Bokov3, Xifa Long3,
and Zuo-Guang Ye3
(1.한림대, 2.Univ. of Tsukuba, 3.Simon Fraser Univ.)
제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트
- 21 -
P-110
Instability of Reset Parameters Due to Intrinsic Property of Conducting Filaments Formed at
Low Compliance Current in Unipolar Resistance Switching
Sang-Chul Na1, Keundong Lee2, Min Chul Chun1, Young-Sun Kwon1, Hye-Jin Shin1,
Ji Seok Im1, Sangik Lee2, Bae Ho Park2 and Bo Soo Kang1*
(1.한양대, 2.건국대)
P-111
The Effects of Etch Stopper Layer on Electrical Properties of Tin monoxide Thin Film
Transistors Prepared by RF Magnetron Sputtering
J.-Y. Kim, J.-M. Song, K. M. Yu, B. S. Bae, and E.-J. Yun*
(호서대)
P-112
A Study on the High Temperature-dependence of Electrical Properties in Solution-deposited
Zinc Tin Oxide Thin Film Transistor Operated in the Saturation Region
K. M. Yu, B. S. Bae, and E.-J. Yun*
(호서대)
P-113
High Temperature Dielectric Relaxations in BiFeO3-(Bi,K)TiO3 Ceramics
Jung Hwan Kim1, Jeong Seog Kim1, Wook Jo2, Chae Il Cheon1*
(1.호서대, 2.UNIST)
P-114
First-principles Investigation of Bistability in Ga- and In-doped CdF2
M. S. Kim* and C. H. Park
(부산대)
ABSTRACTS
Oral Session
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
P1
16:10 ~ 16:40, February 1
Revisit of Lead-free Piezoelectric Material Systems
for Practical Device Applications
Seung-Hyun Kim1*, Sung Sik Won2, Vineeth Venugopal1, Chang Won Ahn2,
Ill Won Kim2, and Angus I. Kingon1
1School of Engineering, Brown University, Providenece, RI02912, USA2Dept. of Physics and Energy Harvest-Storage Center, Univ. of Ulsan, Korea
Legislation is already in place in USA and Europe to ban the use of Pb in industrial products,
including piezoelectric actuators, with exemptions currently being maintained for the ubiquitous lead
zirconate titanate (PZT) class of materials until viable lead-free alternatives are developed. While it
is indeed a formidable materials science and engineering task to create a material to replace the
versatile and well studied PZT system, over the past number of years R&D into lead-free
piezoelectric materials has progressed steadily, leading to the expectation that the commercial
introduction of lead-free piezoelectric devices may occur in the near future, possibly prior to the
expiration of the current EU exemption in 2016. Many companies that currently utilize PZT
transducers and sensors have developed strong knowledge and capabilities in the area of lead-free
materials.
Our research direction is ambitiously designed to make up the knowledge gap and to leapfrog
our academic society into a position in which it can launch practical lead-free piezoelectric
devices, with this position including protectable intellectual property. In developing a strategy we
intensively performed systematic experiments and compared the results with all reported R&D on
lead-free piezoelectric materials (research literature and IP). Based on above data we also had some
careful and selected discussions with other leading groups including representative industry in
lead-free piezoelectric materials for practical applications.
The key strategic research involving the choice of materials, process method, integration into
device assembly and operation parameters of the devices will be discussed here in detail.
*E-mail : [email protected]
Contact Phone : 010-9262-9392
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
P2
08:30 ~ 09:00, February 2
Searching for new frontiers in ferroelectric researches
Tae Won Noh
Dept. of Physics and Astronomy, Seoul National Univ. & Center for Correlated Electron
Systems, Institute of Basic Science
Ferroelectricity, defined by the existence of a switchable spontaneous polarization, has attracted
significant interest since its discovery in 1920. Many decades of extensive research has enabled a
deep understanding of ferroelectric phenomena. More recently, with the rapid advances in thin film
fabrication techniques for oxide materials, new fascinating scientific phenomena, particular to thin
film ferroelectric materials, have been uncovered. As one of new initiatives of IBS, we are
currently searching for new frontiers in ferroelectric researches. Especially, we are investigating a
couple of intriguing effects, including flexoelectricity and ferroelectric tunnel junctions (FTJ).
The flexoelectric effect is the electro-mechanical coupling that generates an electric field by a
strain gradient. Although this phenomenon exists in all dielectric materials, there have been few
studies devoted to it due to the small size of the effects in bulk and difficulties in systematic
control of strain gradient. Our recent studies, however, have shown that strain gradients in epitaxial
thin films can be 6-7 orders of magnitude larger than in their bulk counterparts [1]. Here, I will
review the recent progress regarding the flexoelectric effects in epitaxial ferroelectric thin films,
suggesting that we can make use of flexoelectric effects by carefully controlling the strain gradient.
Investigation of the ferroelectricity at the nanoscale enables us to understand the fundamental
properties of this phenomenon. For instance, the critical thickness for existence of ferroelectricity
and its connection with the effect of the depolarizing field, is a long-standing issue that has
received much research attention. This issue is particularly relevant in the context of the recent
advent of memory devices based on ultrathin layers: so-called FTJ. Recently, we have successfully
fabricated ferroelectric BaTiO3 films just a few unit cells in thickness, on SrRuO3-coated SrTiO3
substrates. Our studies on all-oxide capacitor structures based on these ultrathin films show that the
critical thickness for ferroelectricity is dependent on the top electrode (using SrRuO3, La0.7Sr0.3MnO3,
or without top electrode). This electrode-dependent critical thickness highlights the importance of the
interfacial effect between the ferroelectric material and the electrode for stabilizing ferroelectricity.
References
[1] D. Lee et al., Phys. Rev. Lett. 107, 057602 (2011).
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I1
16:40 ~ 17:00, February 1
Frequency and temperature dependence of incipient piezoelectricity
W. Jo1*, C. Groh2 and J. Rödel2
1School of Materials Science and Engineering, Ulsan National Institute of Science and
Technology, Ulsan 689-798, Korea2Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Straße 2,
64287 Darmstadt, Germany
In response to the world-wide environmental issues, (Bi1/2Na1/2)TiO3(BNT)-based
piezoceramics have been extensively studied over the last two decades. Though the overall
piezoelectric performance of the BNT-based piezoceramics has turned out to be too low to compete
the market dominating PZT-based piezoceramics, the strain properties, i.e., actuating performance,
have been shown to exceed any known piezoceramics, when the composition of materials are
appropriately tuned. A number of compositional studies have shown that the appearance of this
large strain is not confined to certain material classes but a rather universal phenomen on when the
A-site of perovskite structure is co-occupied with heterovalentions. In addition, the observed large
strains are featured by are latively large hysteresis and poor small signal piezoelectric properties. To
unveil the underlying mechanism for the unconventionally large strains, we have performed a
systematic investigation of the effect of measurement frequency and temperature on the strain
behavior. In comparison to the conventional piezoceramics such as PZT, it was observed that this
large strains are more susceptible both to the measurement frequency and to measurement
temperature. In this contribution, we would like to present the detailed experimental results for
proposing a new concept, incipient piezoelectricity, as an origin for the unconventionally large strain
behaviors in BNT-based piezoceramics.
*E-mail : [email protected]
Contact Phone : 052-217-2347 (010-6224-3879)
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I2
17:00 ~ 17:20, February 1
Lead-free piezoelectric BiFeO3-BaTiO3 thick films
Da Jeong Kim, Myang Hwan Lee, Jin Su Park, Tae Kwon Song*
School of Materials Science and Eng., Changwon Nat’l Univ., Gyeongnam 641-773,
Korea
Because piezoelectric multilayer actuator devices are fabricated by thick film processes such as
tape-casting process, it is very important to develop thick films in the new lead-free piezoelectric
system. BiFeO3-BaTiO3 (BF-BT) based system is one of new high Curie temperature and good
piezo-response materials, which have been challenging to texture and bulk by thick film process.
We investigated 0.67BF-0.33BT (BF-BT33) thick films without any templates for the improvement
of grain orientation. The piezoelectric constants of d33 and d33* the sintered thick film were 189
pC/N and 260 pm/V when it was quenched at temperature of 960 oC. The Curie temperature was
about 470 oC. BF-BT33 thick film has remnant polarization Pr = 20 μC/cm2 and coercive field Ec
= 22 kV/cm. These results are as good as those of bulk ceramics in lead-free BF-BT system.
Though polarization direction of (111) in BF, better piezoelectric property is expected in (100)
direction in BF-BT system. Bi4Ti3O12 templates were also tried for the alignment of grains in
BF-BT33 to improve piezoelectric properties. The preliminary results will be presented.
Fig.1 P-E hysteresis loops (a) and S-E curves (b) of the BF-33BT bulk ceramics made by tape
casting method.
*E-mail : [email protected]
Contact Phone : 055-213-3713
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I3
17:20 ~ 17:40, February 1
Practical Applications of Bi0.5(Na,K)0.5TiO3 based Lead-free Piezoelectric
Ceramics
Chang Won Ahn1,*, Gang Ho Choi1, Hee Sung Kim1, Sung Sik Won1, Hae Jin Seog1,
Song A Chae1, Ki Bong Jang2, Yun Po Ok2, Hyon Ho Chong2, and Ill Won Kim1
1Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Korea2R&D Center, Samjeon Co. Ltd, Ulsan 689-934, Korea
In the past decade, lead-free piezoelectric ceramics such as (K,Na)NbO3 (KNN) and
Bi0.5Na0.5TiO3 (BNT)-based materials have been widely studied as replacements for lead-based
materials because of environmental concerns about Pb-containing materials such as lead zirconate
titanate (PZT), which contains more than 60 wt.% Pb. Recently, many studies on lead-free
piezoelectric ceramics have been published. Among various lead-free piezoelectric materials,
BNT-based ceramics are of particular interest because of their high electric-field induced strain and
blocking force, which play important roles in piezoelectric actuator applications. Even though many
studies have reported the physical properties of BNT-based lead-free ceramics, only a few reports
are available about their applications such as multilayer ceramics actuators (MLCAs).
In the present study, we developed a piezoelectric MLCA was fabricated using active layers of
BNKT22:CuO 1.0 mol.% and a Ag-Pd (9:1) internal electrode, and then the performance of a
device with this MLCA was investigated. The average sound pressure level of this device was
comparable to that of the lead-based piezoelectric ceramics speaker in the frequency range between
660 and 20,000 Hz. Therefore, BNKT22:CuO 1.0 mol.% piezoelectric MLCA speakers are good
candidates for lead-free audible sound devices
*E-mail : [email protected]
Contact Phone : 010-8166-3634
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I4
17:40 ~ 18:00, February 1
Piezoelectric Micromachined Ultrasonic Transducer (pMUT) by Granule Spray
in Vacuum Process (GSV)
Jungho Ryu1*, Joontaek Jung2, Hongsoo Choi2, Woon-Ha Yoon1, Dong-Soo Park1,
Jong-Jin Choi1, Cheol-Woo Ahn1, Jong-Woo Kim1, and Hyung-Dong Hahn1
1Korea Institute of Materials Science (KIMS), Changwon 642-8312Daegu Gyeongbuk Institute of Science and Tech.(DGIST) Daegu 711-873
Ultrasonic transducers have been widely used for various applications including medical
imaging, biological therapy, ultrasonic communication, and rangefinder. MEMS based piezoelectric
micromachined ultrasonic transducer (pMUT) is a potential candidate for next generation ultrasonic
transducer since it has significant advantages over traditional ultrasonic transducers. Thin film
fabrication techniques such as sol-gel, sputtering are generally adapted for the fabrication of pMUT
to deposit piezoelectric PZT/AlN thin-film, however, those techniques have limitation of film
thickness which may cause the actuation power and process itself is relatively costly and time
consuming. In order to overcome these shortcomings of typical thin film process for pMUT, we
applied the room temperature granule spray in vacuum process (GSV) to deposit piezoelectric PZT
layer for MEMS pMUT device. PZT thick films were directly patterned by typical PR lithography
and lift off process combined with PZT deposition followed by thermal treatment, top electroding,
DRIE etching process and packaging. The fabricated the pMUT by GSV was characterized by
measuring resonant frequency, electromechanical coupling coefficient, displacement of the membrane
and the ultrasonic intensity. The pMUT by GSV is expected to present enhanced ultrasound
intensity compared with the sol-gel based pMUT as well as reducing the fabrication time and cost.
*E-mail : [email protected]
Contact Phone : 055-280-3378
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I5
19:00 ~ 19:20, February 1
Understanding Defects in Ferroelectrics and Their Application
Soonil Lee
Energy & Environmental Division, Energy Conversion Materials Team, Korea Institute of
Ceramic Engineering and Technology, Geumcheon-gu, Seoul 153-801, Korea
Ferroelectric ABO3 has been systematically investigated in regard to the solubility region
around stoichiometric ABO3 with a combination of techniques regarding the thermodynamics, defect
chemical reactions, and Landau-Devonshire theory. Self-consistent data was obtained and successfully
modeled analytically with defect reactions across the dependant variables of A/B, temperature, and
oxygen partial pressure. From this study, we can determine the defect chemistry of ABO3, obtain
reliable enthalpies of defect formation for the partial Schottky reactions, and determine the
relationship between ferroelectric properties and defect concentration. Those ferroelectric materials
are mostly requiring insulating ferroelectric materials for better ferroelectric properties. However,
there is lack of studies on the ferroelectrics with high concentration of electronic charge carriers.
This paper demonstrates ferroelectric oxides in the unusual condition where the concentration of
electronic carriers is close to a metal-insulator transition; in certain structures and compositions
these materials have properties of interest for ferroelectric based thermoelectric applications. In the
heavily reduced perovskite, tungsten bronze structured, and perovskite layer structured materials,
themopower and electrical conductivity anomalies are observed depending on the carrier
concentration. With this work, the complex nature of the oxygen defect engineered ferroelectrics is
discussed in terms of the thermoelectric properties and coupling of ferroelectrics and thermoelectrics.
Acknowledgements:
Clive A. Randall, Steve Perini, Gaiying Yang, Rudger H. T. Wilke, Susan Trolier-McKinstry, Shujun
Zhang, Sinan Dursun, Cihangir Duran, Takashi Teranishi, Daniel J. Magagnosc, Jonathan A. Bock, Paul
Moses, Jeff Long, Amanda Baker, Weiguo Qu, Petro Maksymovych, Arthur P. Baddorf
*E-mail : [email protected], [email protected]
Contact Phone : 02-3282-2484
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I6
19:20 ~ 19:40, February 1
BiVO4 단결정의 Incommensurate Twin Domain Wall에 관한 연구
장 민수1, 조 성호2*
1부산대학교 물리학과 명예교수, 부산 609-735, 2고려대학교 물리학과 명예교수, 서울 136-701,
BiVO4 은 255 에서 (4/m) 를 갖는 로부터 (2/m) 의
로 (2nd order) 하는 물질이다. 이 물질은 에서 인 로서 서냉
(slow cooling)과 Czochralski 으로 을 시킬 수 있다. (ferroelastic
crystal)은 (ferroelastic phase)의 에서 는 같으면서 서로 다른 둘 의
(orientation state; OS)를 갖는다. 이 물질의 저온상인 강탄성상에서 여러 들이
측정한 Incommensurate Twin Domain Wall(W' )이 각각 다른 값으로 보고되어 있다.
이점에 대하여 본 에서는 그 원인을 조사하기 위하여 과 의 를 이
용하여 Sapriel 과 Aizu의 이론으로 W' ()을 계산하였으며, 그 계산 값과 여
러 연구자가 실험으로 측정한 W' (exp)으로부터 의 층밀리기 변형률()을
계산하였다. 계산결과에 의하면 서냉법으로 시킨 의 층밀리기 , 이
Czochralski법으로 시킨 의 값보다 2배 정도 큰 값을 보였다. 그리고 아래 그림과 같
이 격자상수를 사용하여 계산한 W’ 쌍정구역 벽은 와 일 때 축
(;[100])으로부터 양의 기울기를 갖는 W' 쌍정구역 벽은 와 로 각각
계산되었다. 본 연구 로부터 이 되는 에 에 남아있는 변형력과 강
탄성상으로 상전이하면서 격자변형으로 생성된 변형력에 의한 층밀리기 , 이 W' 쌍정
구역 벽의 형성에 영향을 미쳤다고 생각한다.
*: 본 연구는 대한민국학술원 연구비지원에 의해 수행되었습니다. 책임연구자.E-mail : [email protected] and [email protected]
Contact Phone : 장 민수: 010-3339-0124, 조 성호: 010-3297-3470
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I7
09:00 ~ 09:20, February 2
In-situ TEM Observation of Ferroelectric Domain Switching
J. K. Lee1, G. Y. Shin1, K. Song1, Ho Nyung Lee2, W. S. Choi2, L.-Q. Chen3
and S. H. Oh1*
1Department of Materials Science and Engineering, POSTECH, Pohang 790-7842Materials Science and Techology Division, Oak Ridge National Laboratory, Oak Ridge,
TN 37831, USA3Department of Materials Science and Engineering, The Pennsylvania State University,
University Park, PA 16802, USA
We report in-situ transmission electron microscopy observations of the 180° polarization
switching process of an epitaxial PbZr0.2Ti0.8O3(PZT) thin film capacitor. The preferential, but
asymmetric, nucleation and forward growth of switched c-domains were observed at the
PZT/electrode interfaces, arising due to the built-in electric field induced at each interface. The
subsequent sideways growth of the switched domains was inhibited by the depolarization field due
to the imperfect charge compensation at the counter-electrode and also at the boundaries with
preexisting a-domains, which contributed further to the asymmetric switching behavior. It was found
that the preexisting a-domains split into fine a- and c-domains constituting a 90° stripe domain
pattern during the 180° polarization switching process, revealing that these domains also actively
participated in the out-of-plane polarization switching. The real-time observations uncovered the
origin of the switching asymmetry and further clarified the importance of charged domain walls and
the interfaces with electrodes in the ferroelectric switching processes.
*E-mail :[email protected]
Contact Phone : 054-279-2144
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I8
09:20 ~ 09:40, February 2
Functionality of Domain Walls in BiFeO3
J. H. Lee1,2*, I. Fina2,3, X. Marti3, Y. H. Kim,2,5 D. Hesse2, and M. Alexe2,3
1Department of Quantum Phase and Device, Department of Physics, Konkuk University,
Seoul, Korea2Max Planck Institute of Microstructure Physics, Halle (Saale), Germany
3Department of Physics, University of Warwick, Coventry, United Kingdom4Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles
University, Praha, Czech Republic5Korea Research Institute of Standards and Science, Daejeon, Korea
Ferroelectricity and ferromagnetism had succeeded in the realms of fundamental research, sensing and memory technologies independently before the dawn of multiferroics. The study of domain walls regarded as natural interfaces in these ferroic materials has been brought into attention due to their abnormal properties compared to the host materials. One of these materials, multiferroic BiFeO3 (BFO), which shows high transition temperature of both ferroic order parameters, has been intensively explored because of its unique characteristics of the domain wall, such as increased magnetoresistance, remarkable photovoltaic effect and enhanced conductivity. However, until now there have been only few attempts to control and tune the physical properties of domain walls in a designed way. Among them, tuning the conduction at domain walls is one of the most effective ways with high potential for future applications.
In this presentation, it is proposed to make use of the ferroelectric domain walls in the multiferroic material BFO, which are also conducting and ferromagnetic, and which are intrinsically two dimensional hybrid nano-objects of multiferroic type in a single materials. It is also shown that one can modulate the electronic transport across the ferromagnetic and ferroelectric domain walls in BFO via an external magnetic field, resembling the anisotropic magnetoresistance (AMR) in archetypical metallic ferromagnets. At the same time, BFO preserves two stable and switchable electric polarization states and one can manipulate the ferroelectric domain walls, and thus magnetization, via an electric field.
The electronic transport occurring just through the ferroelectric domain walls is discriminated from the contribution occurring in the bulk, and the conduction mechanism at the domain walls is identified. The extracted contribution of ferroelectric domain walls to the electronic transport occurs to be responsive to an external magnetic field, with a marked unidirectional anisotropy, accompanied by a visible hysteresis, which is ascribed to the coupling of the ferromagnetic domain walls to the bulk antiferromagnetic domains in BFO, similar to that found in ferromagnetic/antiferromagnetic structures. Our results open a perspective for using multiferrocity of domain walls for nanoelectronics.
*E-mail : [email protected]
Contact Phone : 010-8215-4467
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I9
10:30 ~ 10:50, February 1
Strain effect on the visible emission in ferroelectric nanotubes: template and
wall-thickness effect
Y. S. Lee1*, C. H. Jeon1, J. K. Han2, and S. D. Bu2
1Department of Physics, Soongsil University, Seoul 156-7432Department of Physics, Chonbuk National University, Jeonju 561-756
We investigated the strain effect on temperature-dependent photoluminescence property in the
clamped (with template) and free-standing (without template) PbTiO3 (PTO) nanotubes. The
wall-thickness of nanotubes was varied from 25 to 80 nm with the outer diameter fixed to 420 nm.
While all nanotubes show sizable green/yellow emission, the temperature dependent shift of the
emission energy is significantly suppressed in the clamped PTO nanotubes, which is attributed to
the lattice strain driven by the template clamping. This clamping effect is more significant for
thinner nanotubes. Even in the free-standing PTO nanotubes the temperature-dependence of emission
is affected by the wall-thickness. The similar behavior is identified in the Pb(Zr,Ti)O3 nanotubes.
Our finding is the clear manifestation of the template and geometrical shape effect on the optical
property of the nanotubes.
*E-mail : [email protected]
Contact Phone : 02-820-0404
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
I10
10:50 ~ 11:10, February 1
First-principle study on the piezoelectric properties of hydrofluorinated graphene
multilayers
Hye-Jung Kim and Young-Han Shin*
Department of Physics and EHSRC, University of Ulsan, Ulsan 680 749
Hydrofluorinated graphene (C2HF)n possesses electric dipole moment and piezoelectric properties
due to the inversion symmetry breaking under the selective adsorption of H and F atoms. Among
the possible conformations (chair, boat, zigzag, and armchair), the chair (C2HF)n is energetically
most stable. Therefore, we just study the piezoelectric properties of AA-stacked chair (C2HF)n
multilayers. The electric polarization of a chair (C2HF)n monolayer is known to be 47.3 pC/m along
the z direction normal to the surface, and its computed piezoelectric constants are e31=13.0 pC/m
and d31=4.71⨯10-14 m/V [1]. In the dipolar chair (C2HF)n multilayers, we examine their
piezoelectricty and uncompensated depolarization field effects as the number of layers increases. In
our calculations, because of the depolarization field generated in the opposite direction of dipole
moment, the electron and hole carriers are generated on top and bottom layers. Through the
calculation of the average layer piezoelectric constant e31/l in l-layered chair (C2HF)n multilayers, we
confirm that the piezoelectricity of the bilayer is about three times larger than that of the
monolayer and bulk (C2HF)n. Moreover, we find that the induced carriers on the top and bottom
layers play a significant role in the piezoelectric enhancement of the bilayer.
[1] H. J. Kim, M. Noor-A-Alam, J. Y. Son, and Y. -H. Shin, Chem. Phys. Lett. 603, 62
(2014).
*E-mail : [email protected]
Contact Phone : 052-259-1027
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O1
19:40 ~ 19:55, February 1
Antiferroelectric HfxZr1-xO2 thin films for the energy-related applications
M. H. Park*, H. J. Kim, Y. J. Kim, T. Moon, K. D. Kim, Y. H. Lee, and C. S.
Hwang
Department of Materials Science and Engineering and Inter-university Semiconductor
Research Center, College of Engineering, Seoul National University, Seoul 151-744,
Korea.
In this presentation, antiferroelectric (AFE) HfxZr1-xO2 (HZO, x=0.1-0.4) thin films are reported
as new Si-compatible materials for various energy-related applications including pyroelectric energy
harvesting, electrocaloric cooling, electrostatic energy storage, and infrared sensing. Hf0.2Zr0.8O2 film
could work as a pyroelectric energy harvester using the Olsen cycle with the harvested energy
densities (HEDs) of 11.5 J/cm-1 per cycle, which are ~7.6 times larger than the largest value to
date.[1] The electrocaloric effect (ECE) of HZO films was also firstly examined, and the maximum
ΔT values of the Hf0.2Zr0.8O2 film were 13.4K at 307K.[1] The wide temperature range for the
large ΔT values of the HZO films are expected to be promising for the practical cooling cycle
with large magnitude of the reversible work. Moreover, the large capacitance of the HZO films due
to the field-induced transition between the ferroelectric and AFE phase can be used for electrostatic
energy storage and high-charge capacitors. Hf0.3Zr0.7O2 film showed the large energy storage density
(ESD) up to ~46 J/cm3, and the ESD value did not decrease with increasing temperature up to
448K, which was limit of our measurement system.[2] Furthermore, the k2 and Fv values, which are
the figures of merit for conventional pyroelectric energy conversion and infrared detection for
thermal imaging, of the Hf0.2Zr0.8O2 film were 24.4x10-3 and 32.0x10-2 m2/C, respectively, which
prove that Hf0.2Zr0.8O2 is also a promising material for these applications. From these results, thin
HZO films are believed to be a promising candidate for the various energy-related applications.
[1] M. H. Park, H. J. Kim, Y. J. Kim, T. Moon, K. D. Kim, and C. S. Hwang, Nano
Energy, accepted (2014).
[2] M. H. Park, H. J. Kim, Y. J. Kim, T. Moon, K. D. Kim, and C. S. Hwang, Adv. Energy
Mater. 4, 1400610 (2014).
*E-mail : [email protected]
Contact Phone : 02-880-8923
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O2
19:55 ~ 20:10, February 1
Structural properties of strained epitaxial PbVO3 (001) thin films
Seol Hee Oh1, Hye-Jin Jin1, Hae-Young Shin1, Seokhyun Yoon1, Jai Seok Ahn2,
Janghwan Cha3, Suklyun Hong3, Sung Jin Kang4, Miyoung Kim4, and William Jo1,*
1Department of Physics, Ewha Womans University, Seoul, 120-750, Korea
2Department of Physics, Pusan National University, Busan 609-735, Korea3Department of Physics and Graphene Research Institute, Sejong University, Seoul
143-747, Korea4Department of Materials Science and Engineering, Seoul National University, Seoul,
Korea
The layered perovskite PbVO3 (PVO) is an intriguing polar magnetic material because its
strong tetragonal distortion (c/a=1.229) allows VO5 square-pyramidal structure rather than VO6
octahedron. Its unique feature exhibits the 2-dimensional antiferromagnetic (AFM) ordering and large
pyroelectric polarization [1]. It is notable that the c-axis of the PVO films is abnormally elongated
more than 5% on the well-lattice matched LaAlO3 (LAO) substrates [2]. In this study, the phase
formation and structural properties of epitaxial PVO thin films on various crystal substrates,
including SrTiO3 (STO) (001) and LAO (001), were investigated under several deposition condition
ssuch as Ar:O2 ratio, ambient pressure and laser fluence. Restrained oxygen gas is critical during
the deposition process to form the tetragonal PVO (001) thin films with 4-fold in-plane epitaxy on
STO (001) and LAO (001). It is found that c-axis lattice parameter is elongated from 4.67 to 5.02
Å, which is dependent on growth conditions. Theoretical and experimental studies on the phonon
spectra yield insights on the strained structures which V-O1 bondings near 950 cm-1 are separated
into an antisymmetric and asymmetric mode, based on C-AFM structure. Compositional analysis as
well as first-principles calculations suggest a model that V ions occupy in Pb-vacant sites in the
perovskite cell. Due to the enduring tetragonality of the strained structure, PVO will be a candidate
for platform of new multiferroic compounds with mixed with other transition metals.
[1] A. Kumar et al., Phys. Rev. B 75, 060101 (2007).
[2] S. H. Oh et al., J. Phys. D: Appl. Phys. 47, 245302 (2014).
*E-mail : [email protected]
Contact Phone : 02-3277-4066
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O3
20:10 ~ 20:25, February 1
Oxygen octahedral rotation angle of BiFeO3 films depending on structural
modulation of SrRuO3 bottom electrode layer
S. S. Lee1, T. Y. Koo2, J.-Y. Kim2, and J. Y. Jo1*
1School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-712, Republic of Korea.2Pohang Accelerator Laboratory, Pohang University of Science and Technology
(POSTECH), Pohang 790-784, Republic of Korea
Oxygen octahedral rotation of multiferroic BiFeO3 (BFO) has attracted great attentions due to
its effects to electrical and magnetic properties. Octahedral rotation at interface between BFO and
electrode layer remains unexplored. Recently, there has been a report on the control of octahedral
rotation in SrRuO3 (SRO) film on SrTiO3 (001) substrate by controlling the oxygen pressure
during growth.1 Here we demonstrate that the octahedral rotation angle of BFO film is changed
using tetragonal a0a0c tilted-SRO bottom electrodes. In this work, BFO/tetragonal-SRO and
BFO/monoclinic-SRO heterostructures were fabricated to (001)-oriented SrTiO3 substrates at different
oxygen pressures using a pulsed laser deposition technique. The rotation pattern of FeO6 and the
structural symmetry were identified from half-integer reflections using high-resolution X-ray
diffraction technique. The effects depending on octahedral tilting of BFO films on the magnetic and
ferroelectric properties will be presented.
References1Wenlai Lu, Ping Yang, Wen Dong Song, Gan Moog Chow, and Jing Sheng Chen, Phys. Rev. B. 88,
214115 (2013)
*E-mail : [email protected]
Contact Phone : 062-715-3215
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O4
09:40 ~ 09:55, February 2
Creep-free ac dynamics in epitaxial ferroelectric BiFeO3 films
Y. J. Shin1,2,*, B. C. Jeon1,2, S. M. Yang1,2, I. Hwang3, M. R. Cho2, D. Sando1,2,
S. R. Lee1,2, J.-G. Yoon4, and T. W. Noh1,2
1Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747,
Republic of Korea2Department of Physics and Astronomy, Seoul National University, Seoul 151-747,
Republic of Korea3Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul
136-791, Republic of Korea4Department of Physics, University of Suwon, Hawseong, Gyunggi-do 445-743, Republic
of Korea
The switching properties in ferroelectric (FE) films are mainly determined by dynamics of
domain wall (DW) under applied electric field (E). Especially, at finite temperature (T), thermally
activated creep-motion contributed significantly to the DW motion. Many of switching properties of
FE at finite T can only be understood by introducing the creep motion. In spite of such
importance, however, there have been little studies on creep motion under ac-driven force. Here, we
investigate ac-driven hysteretic dynamics of ferroelectric (FE) domains in high quality epitaxial
BiFeO3 (BFO) thin films by frequency (f) dependent P-E hysteresis loops and other switching
characters. Although BFO films are we identically fabricated on different bottom electrodes,
La0.67Sr0.33MnO3 (LSMO) and SrRuO3 (SRO), only BFO/SRO shows nearly creep-free hysteretic
dynamics. We found that such intriguing result comes from the different surface morphology
induced by distinct nature of bottom electrodes and resulting inhomogeneities of internal E.
*E-mail : [email protected]
Contact Phone : 010-7355-8808
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O5
09:55 ~ 10:10, February 2
Reversible Three Out-of-plane Ferroelectric States in BiFeO3 Thin Films
J. H. Lee1*, K. Chu1, K.-E. Kim1, J. Seidel2, and C.-H. Yang1,3
1Department of Physics, KAIST, Daejeon 305-701, Republic of Korea2School of Materials Science and Engineering, University of New South Wales, Sydney,
New South Wales 2052, Australia3KAIST Institute for the NanoCentury, KAIST, Daejeon 305-701, Republic of Korea
Existing multi-level polarization devices have been based on the rigorous control of 180°
domain switching between two polarizations (“up” and “down”). However, as a new concept of
multi-level polarization devices, non-180° domain switching has not been utilized since it increases
the local elastic energy around the switching domains by making unstable ferroelectric domain
walls. In this presentation, we report on a discovery of non-180°-type out-of-plane (OOP) three-step
switching in BiFeO3 (BFO) thin films deposited on (110)pc-oriented GdScO3 substrates. We realized
an prototype of OOP-three-level system through electric-field-switching experiments using
piezoresponse force microscopy (PFM). We constructed a simple theoretical model based on the
phenomenological Landau theory for a better understanding of the observed three-step switching. In
addition, slow-scan-direction-dependent PFM poling experiments showed the switching characteristics
of the (110)pc-oriented BFO system, and the result agreed with the theoretical expectation from our
model. Our results open an opportunity to materialize three-level memory devices which use the
missing “middle” state.
*E-mail : [email protected]
Contact Phone : 042-350-2553
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O6
11:10 ~ 11:25, February 2
Freestanding ZnO Nanorode/Graphene/ZnO Nanorod Epitaxial Double
Heterostructure for Improving Piezoelectric Nanogenerator
Dong-Myeong Shina, Ermias Libnedengel Tsegea, Seok Hee Kangb, Wanchul Seungc,
Sang-Woo Kimc, Hyung Kook Kima, Suck Won Hongb,*, and Yoon-Hwae Hwanga,*
a Department of Nanomaterials Engineering & BK21 Plus Nanoconvergence Technology
Division, Pusan National University (PNU), Miryang 627-706, Republic of Korea
b Department of Cogno-Mechatronics Engineering, Pusan National University (PNU),
Busan 609-735, Republic of Korea
c SKKU Advanced Institute of Nanotechnology (SAINT) & Center for Human Interface
Nanotechnology (HINT), SKKU-Samsung Graphene Center, Sungkyunkwan University
(SKKU), Suwon 440-746, Republic of Korea
We present a simple strategy for fabricating the freestanding ZnO nanorod/graphene/ZnO
nanorod epitaxial double heterostructure. The characterization of the epitaxial double heterostructure
by using SEM, and Raman scattering spectroscopy reveals the key process and working mechanism
of a formation of the heterstructure. The mechanism is discussed in detail in term of the
decomposed seed layer and the vacancy defect of graphene. The resulting improvement in the
number density of nanorods has a direct beneficial effect on the double side heterstructured
nanogenerator performance. The total electrical outputs are improved up to ~ 2 times compared to
those of a single heterostructure due to the coupling of the piezoelectric effects from both upward
and downward grown nanorods. The facile one-step fabrication process suggests that epitaxial
double heterostructure would improve the performance of electrical and optoelectrical device, such
as touch pad, pressure sensor, biosensor and dye-sensitized solar cells.
*E-mail: [email protected] (S.W. Hong), [email protected] (Y.-H. Hwang)
Contact Phone : 055-353-5274
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O7
11:25 ~ 11:40, February 2
Applications of Transmission Line Impedance Models in Materials Research
Focusing on Energy Devices
Eui-Chol Shin, Jong-Sook Lee*
School of Materials Science and Engineering, Chonnam National University, Gwangju
500-757, Korea
Transmission line impedance models for the distributed circuit elements in electrical engineering
can represent the diffusion process involved in many energy devices such as fuel cells, batteries,
and solar cells, which often critically determines the performance. Although impedance spectroscopy
is widely applied, transmission line models appear to remain mystified and insufficiently utilized
and ubiquitous presence seems to cause further confusion. 1) We have successfully applied them to
the porous gas electrode kinetics of high temperature solid oxide fuel cells for the evaluation of the
surface diffusivity and dissociative adsorption/desorption reaction according to non-faradaic chemical
reaction model by Mizusaki, distinguished from the gas phase diffusion, for both oxygen and
hydrogen electrodes. The process turns out to be in exact analogy to the diffusion-recombination
process in DSSCs. 2) The chemical diffusion and reaction in particulate active cathode materials of
lithium ion batteries needs a spherical (3-D) solid-state diffusion model incorporated into the 1-D
porous electrode model. Modeling of parallel solid state reaction paths deconvoluted the kinetic
parameters according to the nanocomposite model in high energy layered oxide materials. 3)
Generalized transmission line model for mixed conductors by Jamnik and Maier has been
successfully applied to the olivine-type electrode material for the evaluation of ionic and electronic
conductivity as well as the chemical diffusivity. 4) Pneumatochemical impedance derived by the
Laplace transform of the hydrogen storage kinetics monitored by Sievert’s setup is characterized by
the inductive loop and the oscillation. 5) Dispersive AC response of the percolative conductive
network in the insulating matrix, often discussed as electron diffusion kinetics of electrons, should
be interpreted as purely electrical transmission line network, where the capacitance parameter can be
related to the microstructural distribution.
*E-mail : [email protected]
Contact Phone : 062-530-1701
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O8
11:40 ~ 11:55, February 2
Low operation voltage of ferroelectric polymer devices induced by X-ray
irradiation-mediated structural transition
H. J. Lee1, O. W. Kwon2, J. H. Kim1, J. W. Kim3, H. J. Lee1, J. H. Kwak1, J. M.
Kim1, Y. S. Kim2, D-Y. Kim1, and J. Y. Jo1*
1School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-712.2School of Advanced Materials Science and Engineering, Sungkyunkwan University
(SKKU), Suwon, Gyeonggi-do 440-746.3Pohang Accelerator Laboratory, Pohang 790-834 .
Ferroelectric polymer, poly(vinylidene fluoride-trifluoroethylene)[P(VDF-TrFE)], has attracted a
lot of interest for applications including non-linear capacitors, non-volatile memories, and field effect
transistors. The higher coercive field in comparison to inorganic ferroelectrics is the most important
problems to design devices which can operate with a high switching speed at a low voltage
operation. A reduction of film thickness has been simply suggested to reduce the coercive voltage.
However, a thin film with a thickness less than 100 nm does not only increases leakage current,
but also still shows an increase of coercive voltage above 80 Hz. In this study, we achieved the
reduced coercive field with introducing non-polar phase using X-ray irradiation onto P(VDF-TrFE).
P(VDF-TrFE) films on ITO/glass were irradiated with hard X-rays at 5D beam line (10 keV)
of Pohang Accelerator Laboratory. We controlled the phase transition by varying an irradiation time
and an X-ray photon flux. The phase transition became significant with X-ray irradiation time after
500 sec. We observed irreversible phase transition from ferroelectric β to non-polar α phase of
P(VDF-TrFE) via X-ray irradiation. Finally, we found that coercive voltage was reduced by 47%
after the irradiation..
*E-mail : [email protected]
Contact Phone : 062-715-3215
제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스
O9
11:55 ~ 12:10, February 2
Why no ferroelectricity in polar piezoelectric GaFeO3?
Seungwoo Song1* and Hyun Myung Jang1,2
1Division of Advanced Materials Science(AMS) and Department of Materials Science and
Engineering, Pohang University of Science and Technology(POSTECH), Pohang 790-7842Department of Physics, Pohang University of Science and Technology (POSTECH),
Pohang 790-784
Gallium ferrite (GaFeO3) has been extensively studied by virtue of its well-known room-temperature piezoelectricity and magnetoelectric coupling at low temperatures. GaFeO3
possesses an orthorhombic non- centrosymmetric symmetry with the space group Pna21 (or Pc21n). Thus, it is expected to show ferroelectricity at room temperature. Until now, however, there is no direct evidence of the ferroelectricity or the existence of high-temperature prototypic phase (paraelectric) in GaFeO3.
In the present research, we have deposited GaFeO3 thin film on a hexagonal SrTiO3(111) substrate by employing pulsed laser deposition (PLD) to obtain a strain-free high-crystalline thin-film form. Using diffraction and microscopy methods, we confirm well-ordered multi-structures of GaFeO3/SrRuO3(111)/SrTiO3(111) with the polar c-axis along the growth direction. To investigate piezoelectric and ferroelectric responses of GaFeO3 films, we adopt dynamic contact electrostatic force microscopy (DC-EFM) method which is identical to piezoelectric force microscopy (PFM) in terms of the bias application and signal detection. Although we are able to switch the piezoelectric phase of a particularly chosen region by applying a negative-to-positive alternative bias voltage (up to ±10V), the switched piezoelectric phase returns to the initial (unswitched) state as soon as we turn off the external bias. These observations clearly indicate that the measured piezoelectric-phase switching do not show any evidence of the ferroelectricity but demonstrates the existence of piezoelectricity in the polar-axis-oriented GaFeO3 film.
In order to theoretically support the experimental results, we have carried out density-functional theory (DFT) calculations by systematically displacing the Ga-ion which is known to be responsible for manifesting piezoelectricity. By performing lattice dynamics calculations using the Bilbao crystallographic sever, we have found that the space-group symmetry corresponding to the centro-symmetric prototypic phase of GaFeO3 is Pnna and the Pnna-to-Pna21 phase transition (for manifesting piezoelectricity) is mediated solely by the polar Γ4
- normal mode. On the basis of DFT calculations, we conclude that the difficulty of observing ferroelectricity in the polar Pna21 GaFeO3 mainly originates from the exceptionally high potential-energy barrier between the two degenerate polar ground states. This clearly elucidates the observed piezoelectricity as well.
*E-mail : [email protected]
Contact Phone : 054-279-2819
ABSTRACTS
Poster Session
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-1
Dependence of electrical properties of Sol gel derived PZT thick films on
crystalline orientation
V. Annapu Reddy1*, Jong-Jin Choi1, Jungho Ryu,
1Korea Institute of Materials Science (KIMS), Changwon 642-831
The effects of crystalline orientation on the electrical properties of lead zirconate titanate (PZT)
thick films (over 2 -thick) deposited by the sol-gel method have been studied. The orientation
and microstructure of the thick films were characterized by X-ray diffraction (XRD) and scanning
electron microscopy analysis. XRD results indicate that the strong [111]- or [100]-preferred
orientation of the PZT thick films could be observed by controlling the pyrolysis conditions after
spin-coating. The texture was mainly [111]-orientation for pyrolysis temperatures from 330 to 400
°C, and changes to [100]-orientation for pyrolys is temperatures at or above 450°C after annealing
at 650°C for 5 min. The formation of preferred orientation could be considered from the results of
migration speed of deposited species and internal strain energies between the substrate and the film.
Different crystalline orientations also lead to change in electrical properties such as dielectric
constant, polarization values, leakage current and fatigue behavior.
*E-mail : [email protected]
Contact Phone : 055-280-3352
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-2
Enhanced magnetoelectric coupling in a PZT/Metglas bilayer
thick film composite
Haribabu Palneedi1,2, Deepam Maurya3, Shashank Priya3, Suk-Joong L. Kang1*,
Si-Young Choi4, and Jungho Ryu2
1 Materials Interface Laboratory, Department of Materials Science and Engineering,
Korea Advanced Institute of Science and Technology (KAIST), Daejeon.2 Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon.
3 Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech,
Blacksburg, VA, USA4 Advanced Characterization and Analysis Group, Korea Institute of Materials Science
(KIMS), Changwon, Korea
We studied magnetoelectric (ME) coupling in a bilayered lead zirconate titanate (PZT)/Metglas
(FeBSi) thick film composite. A unique approach involving room-temperature coating (GSV; Granule
Spray in Vacuum) and localized annealing (laser irradiation) of PZT films was adopted to address
problems involved in the processing of PZT/Metglas film-based ME composites. Very strong ME
interactions between PZT and Metglas resulted in an extremely high ME coefficient of 2790
mV/cmOe under a low-bias magnetic field (HDC = 60 Oe) and in an off-resonance (f = 1kHz)
condition. The ME coefficient obtained in this study was two orders of magnitude larger than that
reported for PZT/Metglas film composites. The results of dielectric, ferroelectric, and optical
measurements and microstructural observations of this PZT/Metglas composite were also in line with
the significantly enhanced ME coefficient. The current fabrication approach can be exploited for
tuning the ME properties of film composites and can be extended to other piezoelectric/magnetic
composite systems as well. This study opens up new possibilities in designing laminate composites
which would be suitable for various ME device applications.
*E-mail :[email protected]
Contact Phone : 042-350-4113
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-3
Enhanced polarization of hard polar phases in a heterphase polycrystalline
G. Y. Kim1, S. D. Kim1, Y. M. Rhyim1, S. Y. Yoon2 and S. Y. Choi1*
1Advanced Characterization and Analysis Group, KIMS, Changwon, 642-8312School of materials Science and Engineering, Pusan National University, Busan,
609-785
Polar and non-polar phase composite has the various advantages in terms of piezoelectricity,
such as easy polarization switching, high polarization saturation (Ps), and large electrostrain. To this
end, we fabricated the composite polycrystalline of the polar and non-polar phases and observed the
antiferroelectric-like polarization behavior, which is obviously different to single the non-polar phase
(Bi0.5(Na0.75K0.25)0.5TiO3 BiAlO3) or polar phase (Bi0.5(Na0.8K0.2)0.5TiO3). In this composite, the
keypoint was to activate the ferroelectric polar phases with a high coercive field (Ec) at the low
external electric field (< 2 kV/mm). Therefore, in this study, we aimed to directly visualize the
polarization of the polar phase via transmission electron microscopy (TEM). First of all, TEM
micrographs and selected area electron diffractions patterns (SADPs) show the polar phase exists as
a core in the grain interior surrounded by the non-polar phase shell. The in-situ electric biasing
TEM experiments confirm that the ferroelectric domains in the polar phase are aligned even under
a low external field of 1 kV/mm. This unique polarization behavior of the polar phase is due to
the augmented internal electric field from non-polar phase under the electric biasing and can be
verified by simple modeling system based on the dielectric divergence in the heterophase structure.
AcknowledgementThis research was supported by Global Frontier Program through the Global Frontier Hybrid Interface Materials(GFHIM) of the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (2013M3A6B1078872).
*E-mail : [email protected]
Contact Phone : 010-3206-0229
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-4
Temperature Dependance of Magnetic Domains in Co2Z-type Hexaferrite: TEM
Studies by In-situ Heating and Lorentz Microscopy Methods
Sung-Dae Kim1*, Tae-Won Lim1,2, Gi-Yeop Kim1,3, Kee Hoon Kim4
and Si-Young Choi1
1Advanced Characterization and Analysis Group, Korea Institute of Materials Science
(KIMS), Changwon 642-8312Department of Nano Science and Engineering, Kyungnam University, Chanwon 631-701
3School of Materials Science and Engineering, Pusan National University, Pusan 609-7354Department of Physics and Astronomy, Seoul National University, Seoul 151-747
In the past decades, there has been a huge revival of interest in multiferroics, wherein magnetism and ferroelectricity coexist [1-3]. However, it was proved to be a difficult problems to find plausible candidates having strong magnetoelectric (ME) coupling at moderate operating temperature. Recently, this long-standing challenges have been overcome by discovering the Co2Z-type hexaferrite (Ba, Sr)3Co2Fe24O41 containing a unique spin structure in room-temperature [4-5]. The Co2Z-type hexaferrite contains the net magnetic moments in alternating large and small blocks along the c-axis. The strong ME effects of the Co2Z-type hexaferrite can be understood in terms of a transverse conical spin configuration of the magnetic building blocks at room-temperature, through the inverse Dzyaloshinskii-Moriya (DM) mechanism. Hence, the magnitude and direction of the net magnetic moment, according to the operating temperature (T) and applied magnetic field (H) range, is the key parameter for the realization of the promising ME effects. Consequently, T-dependent magnetic structures of the Co2Z-type hexaferrites were examined by neutron diffraction studies [3,6], providing a detailed informations about the transition temperature of the spin configurations. In the present study, we visualized the T-dependent magnetic domain structures in a Co2Z-type hexaferrite Ba0.52Sr2.48Co2Fe24O41, to achieve more clear understanding of thermally activated dynamics of the magnetic moment, via in-situ heating transmission electron microscopy combined with the Lorentz microscopy method. A series of the defocused Fresnel images with continuous temperature ramping was taken, showing the magnetic moments rotation dynamics and its transition temperature. Also, the direction of the magnetic moments was clearly defined by magnetization distribution maps, calculated using a phase reconstruction technique based on a transport-of-intensity equation (TIE).
[1] Sang-Wook Cheong and Maxim Mostovoy, Nature Mater. 6, 13 (2007).[2] Shintaro Ishiwata et al., Science 319, 1643 (2008).
[3] Minoru Soda et al., Phys. Rev. Lett. 106, 087201 (2011).
[4] Yutaro Kitagawa et al., Nature Mater. 9, 797 (2010).
[5] Sae Hwan Chun et al., Phys. Rev. Lett. 108, 177201 (2012).
[6] Yukio Takada et al., J. Appl. Phys. 100, 043904 (2006).
AcknowledgementThis research was supported by Global Frontier Program through the Global Frontier Hybrid Interface Materials(GFHIM) of the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (2013M3A6B1078872).
*E-mail : [email protected]
Contact Phone : 055-280-3551
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-5
Electric and structural properties in polar/non-polar multilayers.
Kil-Dong Sung1*, Gi-Yeop Kim1,2, and Si-Young Choi1
1Advanced Characterization and Analysis Group,
Korea Institute of Materials Science (KIMS), Changwon 641-8312School of Materials Science and Engineering, Pusan National University, Pusan 609-735
To fabricate ferroelectric devices even sensitive to the low electric field, researchers have tried
to fabricate the ferroelectric oxides in various types that exhibit the low electric coercive field
together with the large electric polarization. In this poster, we propose that a ferroelectric layer
sandwiched by two high-k layers can effectively reduce the coercive electric fields, hence improve
the ferroelectric effects. To this end, we deposited SrTiO3/PbTiO3/SrTiO3/SrRuO3 multilayers on
SrTiO3 substrates by a pulsed laser deposition technique. The thin films show clear interfaces with
epitaxial crystal structures, and significant reductions of electric coercive fields with almost same
remnant electric polarization values of bare PbTiO3 thin films. In addition, in-situ transmission
electron microscopy results show that as-grown PbTiO3 ferroelectric multi-domains start to switch
and finally become a ferroelectric mono-domain at lower external electric fields, compared to the
PbTiO3/SrRuO3 on SrTiO3 substrate without high-k layers. To understand the phenomena we
calculated effective electric fields of the PbTiO3 layer as well as induced interfacial electric
polarizations. Our results imply that the diverse dielectric constants between polar and non-polar
layers in combination with the heteroepitaxial film growth could result in an important key role in
fabricating the ferroelectric devices sensitive to the low electric field.
AcknowledgementThis research was supported by Global Frontier Program through the Global Frontier Hybrid Interface Materials(GFHIM) of the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (2013M3A6B1078872).
*E-mail : [email protected]
Contact Phone : 055-280-3275
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-6
Cationic ordeirng and magnetic properties of Re-based double perovskite oxides
T. W. Lim1,2, S. D. Kim1, K. D. Sung1, H. J. Jean3, J. D. Yun2, M. S. Choi1
and S. Y. Choi1*
1. Korea Institue of Materials Science, Changwon 642-831, Korea2 Department of Nano science and Engineering, Kungnam University, Changwon
631-701, Korea3 Department of Physics, Pusan National University, Busan 609-785, Korea
Ferromagnetic double perovskites have recently attracted great attention due to their presumed
half-metallicity as well as high curie temperature. Cationic ordering in two Re-based double
perovskites Sr2FeReO6 (SFRO) and Sr2CrReO6 (SCRO) is investigated in a viewpoint of antisite
defect (AS) through combination of experiments and first principles calculations. To control the
cationic ordering, SFRO-xRe (0 mol% - 15 mol%) and SCRO-xRe (0 mol% - 10 mol%)
solid-solution samples were synthesized by conventional solid-state method. From the fabricated
samples, we selected SFRO and SCRO samples with the similar cationic disordering but we found
that atomic structural array of ASs behaves different in SFRO and SCRO. Antiphase-boundary-like
feature, due to the preferentially clustering interaction of ASs, forms in the SFRO samples, whereas
the ASs are spatially distributed in the whole sample of SCRO. Futhermore, we observed that the
clustered ASs in a form of antiphase-boundary more largely deteriorate ferromagnetism, indicating
that the array behavior as well as the amount of atomic defects are important keys to affect the
physical properties.
Acknowledgement
This research was supported by Global Frontier Program through the Global Frontier Hybrid
Interface Materials(GFHIM) of the National Research Foundation of Korea(NRF) funded by the
Ministry of Science, ICT & Future Planning (2013M3A6B1078872).
*E-mail : [email protected]
Contact Phone : 010-2922-6824
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-7
Growth and Characterization of LaAlO3 Thin Films Grown by off-axis RF
Sputtering
D. H. Kim1, C. W W. Bark1*,
1Department of Electrical Engineering, Gachon University,San 65, Bokjeong-dong,
Sujeong-gu, Seongnam, Gyeonggi-do, 461-701, Republic of Korea
In recent years a conducting state was reported at the interface between the two band
insulators, LaAlO3(LAO), and SrTiO3(STO).This discovery of a two-dimensional electron gas
(2DEG) has brought about innovative applications in the area of nanoscale oxide devices. Currently,
pulsed laser deposition (PLD) is the dominant deposition technique used for creating oxide
interfacial 2DEG hetero structures. However, PLD is not suitable growth technique for the device
application due to its small deposition area (~5 mm x 5mm). On the other hand, 90° off-axis
sputtering is a scalable process that has been shown to create smooth, epitaxial films that are
uniform over a large area.
Here by, we report the Growth and chracterization of the LaAlO3 on SrTiO3 substrate using by
RF sputtering which allows uniform films over a large area. Unlike typical RF sputtering, we used
90° off-axis sputtering which enables fabrication of high quality LAO films without secondary phase
particles. The electrical transport properties of the LaAlO3/SrTiO3 heterointerface are similar to those
grown by pulsed laser deposition(PLD).
Thus, we investigated growth condition of LaAlO3/SrTiO3 heterointerface using 90° off-axis RF
sputtering to fabricate high quality LaAlO3 thin film with different regime of growth conditions.
*E-mail : [email protected] Phone : 031-750-5351
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-8
Synthesis and characterization of UV treated bismuth titnate doped TiO2
M. G. Song1, and C W bark1*
1Department of Electrical Engineering, Gachon University, 1342 Seongnam-daero,
Seongnam-si, Gyeonggi-do 461-701, Korea
The wide band gap of complex oxides has limited their use in photovoltaic cells. To tune the
bandgap of complex oxides, nano-sized bismuth titanate powders were prepared by a high-energy
ball milling process for optoelectric applications. However, the bismuth titnate mixed TiO2 can be
easily separated on the FTO glass during the spin coating. A remarkable surface wettability
transition can be easily achieved by ultraviolet(UV) illumination. To avoid the separation problem,
we were treated bismuth titanate by using ultraviolet(UV) to change the wettability between
hydrophilic abd hydrophobic of bismuth titanate. This study described the synthesis and
characterization of UV treated bismuth titanate doped TiO2.
*E-mail : [email protected]
Contact Phone : +82-31-750-5351
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-9
Effect of Yb doping on the multiferroic properties of epitaxial BiFeO3 thin
films
Yoonho Ahn,1 Jeongdae Seo,1 Jong Yeog Son1,* and Joonkyung Jang2,*
1Department of Applied Physics, Kyung Hee University, Yongin 446-701
2Department of Nanomaterials Engineering, Pusan National University, Busan 609-735
We report the enhanced multiferroic properties of a ytterbium (Yb)-doped BiFeO3 thin film
(Bi0.85Yb0.15FeO3) deposited on a (001) SrRuO3/(100) SrTiO3 substrate by pulsed laser deposition.
The crystal structure, surface morphology, ferroelectric domain structure, and the electrical and
magnetic behavior of the epitaxial Bi0.85Yb0.15FeO3 film, 100 nm in thickness, were investigated. The
results were compared with those of an undoped BiFeO3 thin film. The x-ray diffraction patterns
showed that both films have tetragonal-like crystal structures. Atomic force microscopy showed that
the Bi0.85Yb0.15FeO3 and BiFeO3 films have flat and clear surface steps, characteristic of a
layer-by-layer growth mechanism. Furthermore, the strip-like ferroelectric domain structures were
clearly observed in piezoelectric force microscopy. The Bi0.85Yb0.15FeO3 films had significantly
higher remanent polarization of approximately 73 μC/cm2 and lower leakage current compared to
the BiFeO3 thin film. Ferromagnetic enhancement was also observed in the Bi0.85Yb0.15FeO3 film at
room temperature.
*E-mail : [email protected], and [email protected]
Contact Phone : 031-201-3487
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-10
Source Concentration and Temperature dependence of Microstructure and
Properties of ZnO thin films deposited by MOCVD using Ultrasonic
Nebulization
C. H. Lee*, M. S Choi
Department of Materials Engineering, Keimyung University, Daegu 704-701
ZnO, which has hexagonal wurtzite structure, is a piezoelectric material and a wide band gap
semiconductor. Thin films of pure or doped ZnO are used in SAW filter, transparent electrode, and
transparent transistor. Generally it is made by sputtering and there are some reports on the
deposition by ALD or PLD. However there are few reports on the deposition of ZnO thin films by
CVD which has many advantages such as high deposition rate, uniform deposition in large area,
high step coverage, etc.. This seems to be due to the rarity of zinc compound applicable to CVD
source. Recently we have reported that ZnO thin films were deposited on soda lime glass substrates
at the low substrate temperatures of 225 350 by MOCVD using ultrasonic nebulization, using
zinc acetylacetonate as a precursor for Zn source, which is not appropriate to the source material in
the usual CVD. In this work, the effects of source concentration and deposition temperature on the
microstructure and properties of films were investigated.
Source concentration and/or deposition temperature affect largely on the rate and mechanism
of film growth. At the condition of high source concentration and low deposition temperature very
small nano-sphere crystallites of about 20 nm diameter were formed compactly on the substrate
surface at the early stage of deposition. And then new nuclei, which successively formed on these
crystallites, coalesced to form columnar grains with a plate-pillar structure. This columnar formation
may have resulted from the supersaturation of the reactant gas adsorbed on the surface because the
surface chemical reaction rate was lower than the mass transfer rate. These films had some open
spaces between the columnar grains and the grain size at the surface increased with film thickness.
On the contrary, at the condition of low source concentration and high deposition temperature
islands of crystallites with the shape of a hexagonal pyramid were formed on the substrate surface
scatteredly at the early stage of deposition and they grew to form a connected thin film with a
large grain size at about 100 nm thickness. Then the film grew to form a dense rock-like structure.
This difference in microstructure resulted in the difference in electrical conductivity of films.
*E-mail : [email protected]
Contact Phone : 053-580-5566
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-11
Effect of Bi(Ni0.5Ti0.5)O3 doping on structural and piezoelectric properties of
BiFeO3-BaTiO3 ceramics
I. J. Hwang1, D. Do1*, M. H. Lee2, J. S. Park2, D. J. Kim2, T. K. Song2, M.-H. Kim2,
S. W. Kim3 and W.-J. Kim3
1Department of Advanced Materials Engineering, Keimyung University, Daegu 704-7012School of Materials Science Engineering, Changwon National University, Changwon
641-7733Department of Physics, Changwon National University, Changwon 641-773
Piezoelectric ceramics are widely used for electromechanical systems such as sensors and
actuators. High-temperature piezoelectric ceramics are, particularly, required in the automotive,
aerospace, and energy industries. However, traditional lead-free piezoelectric ceramics including
(Bi,Na)TiO3, (Bi,K)TiO3, (K,Na)NbO3 systems cannot operate at high temperature although a
remarkable improvement in piezoelectric properties is achieved. Recently, lead-free
(1-x)BiFeO3-xBaTiO3 systems with high Curie temperature and a morphotropic phase boundary with
the coexistence of both rhombohedral and cubic phases at x=0.33 have been introduced [1].
Although many studies have been performed in (1-x)BiFeO3-xBaTiO3 systems, almost no study has
been done on 0.67BiFeO3-0.33BaTiO3. In this study, structural and piezoelectric properties of
(1-x)(0.67BiFeO3-0.33BaTiO3)-xBi(Ni0.5Ti0.5)O3 (x=0, 0.01) ceramics were studied. By substitution of
the small amount of Bi(Ni0.5Ti0.5)O3, reduced average grain size and improved piezoelectric
properties were observed. Direct and converse piezoelectric coefficient of
0.99(0.67BiFeO3-0.33BaTiO3)-0.01Bi(Ni0.5Ti0.5)O3 ceramics were 165 pC/N and 300 pm/V,
respectively. Also observed Curie temperature was 455 . This result indicates that
0.99(0.67BiFeO3-0.33BaTiO3)-0.01Bi(Ni0.5Ti0.5)O3 ceramics can be one of the promising candidates
for a high Curie temperature lead-free piezoelectric ceramics.
[1] M. Mahesh Kumar et al., J. Appl. Phys. 87, 855 (2000).
*E-mail : [email protected]
Contact Phone : 053-580-5565
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-12
Growth of graphene using pulsed laser deposition technique with in-situ
monitoring by reflection high energy electron diffraction
J. H. Kwak1, H. J. Lee1, S. S. Lee1, G. Anoop1, and Ji Young. Jo1*
1 School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-712, Republic of Korea.
Graphene has attracted considerable attention due to its outstanding properties such as high
carrier mobility and transparency. One of the most common methods to grow the graphene is
chemical vapor deposition synthesis on the metal catalytic films. However, it requires additional
transfer process onto desired substrate. It is inevitable to generate structural defects such as wrinkle
and crack or surface contaminations resulting in degradation of electrical properties. In this
presentation, we show that pulsed laser deposition (PLD) technique with reflection high energy
electron diffraction (RHEED) can be used to grow the graphene films on the substrate directly.
A few-layer nanocrystalline graphene was grown on the AlN/Si substrate without metal catalyst
films through the laser ablation of highly ordered pyrolytic graphite target at substrate temperature
of 700 ~ 850 . Base and working pressure of process chamber were maintained around 10-7
torr. A KrF excimer pulse laser with an energy 175 mJ was used. Structural characteristics were
investigated by RHEED, micro-Raman spectroscopy, scanning electron microscope, and X-ray
photoemission spectroscopy. The electrical properties were measured using Van der Pauw method.
The RHEED results correlated with Raman spectroscopy revealed that the mono-layer graphene
cannot be formed due to their high defect concentration, although the first layer on the substrate
was formed completely. However, a few-layer nanocrystalline graphene was formed with an increase
of growth time and temperature, which indicates structural quality to depend on growth time and
substrate temperature.
*E-mail : [email protected]
Contact Phone : 062-715-3215
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-13
Synthesis of catalytic LaMnO3+d nanoparticles by laser ablation in solution
W. S. Kim1, G. Anoop1, H. J. Lee1, S. S. Lee1, J. H. Kwak1, H. J. Lee1,
and Ji Young Jo1*
1 School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-712, Republic of Korea.
The catalysts play an important role in energy devices such as fuel cell and Li-air batteries.
The LaMnO3+d particles have been commonly used for catalyzing the oxygen reduction reaction due
to a high catalytic activity. Generally, in catalytic reaction, nanometer-sized (<10 nm) particles have
a large surface area which leads to a high catalytic efficiency. However, it is hard to achieve
nanometer-sized particles from typical chemical reaction synthesis. The laser ablation synthesis in
solution (LASiS), which is a simple, fast, and clean process, is suitable to achieve nanometer-sized
LaMnO3+d particles by controlling laser parameters. Also, graphitized carbon support provides a lot
of oxygen-containing functional groups (e.g., hydroxyl and carboxyl) on the carbon surface to be
active sites for the deposition of nanometer-sized LaMnO3+d particles.
The LaMnO3+d target was prepared using a solid state reaction with La2O3 and MnO2 powder
calcinated at 900 for 12 hours. A disk-pellet was made by cold isostatic pressure method. The
pellets were sintered at 1200 for 24 hours. The target soaked in various solutions including
distilled water, ethanol, and SDS aqueous was exposed to a KrF excimer pulse laser, which
produces a beam with a wavelength of 248 nm. In this work, laser fluence value is ranged from
0.5 to 1 J/cm2. Graphitized carbon black (GCB) powder is treated by using nitric acid and
ammonia in oil bath. Then, LaMnO3+d colloidal solution and treated GCB are mixed by typical
solution method. The structural characteristics were investigated by a scanning electron microscopy
and an X-ray diffraction instrument.
*E-mail : [email protected]
Contact Phone : 062-715-3215
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-14
Superlattice of FeSexTe1-x superconductor thin films
S. Seo1, J. H. Kang2, C. B. Eom2, and S. Lee1*
1School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-7122Department of Materials Science and Engineering, University of Wisconsin-Madison, WI,
US 53706
In recent years, a huge effort has been devoted to understand the fundamental physical
properties and enhance superconducting properties of Fe based Superconductors (FeSC). Among
FeSC family, arsenic free and simple PbO-type structured FeSexTe1-x (FST) has attracted much
research interest. Many studies have been done to obtain higher critical current density (Jc) and
upper critical field (Hc2) by incorporating artificial pinning centers in FeSC thin films. In this study,
a number of oxide materials and undoped FeTe (FT) have been used an insertion layer material to
form superlattice with FST to obtain high Jc and Hc2. Among them, by using CeO2 which has
similar effective lattice constant and good chemical stability with FST, FST/CeO2 superlattice has
been successfully fabricated. The superlattice showed high Jc and Hc2 due to the generation of
effective pinning centers. Furthermore, we have fabricated FT/FST superlattice structure and also
found that pinning centers such as nano-particle arrays were generated at the interface between FT
and FST. We will discuss the structural properties and superconducting properties of FST/CeO2
superlattice and FST/FT(FeTe) superlattice grown on single crystal CaF2 substrates. These
superlattices show better superconducting properties than single layers without severe degradation of
superconducting transition temperature (Tc) and structural properties. The successful growth of
FST/oxide superlattice could give us the possibility to fabricate potential device such as FST
(superconductor) - CeO2 (oxide) - FST (superconductor) junction.
*E-mail : [email protected]
Contact Phone : 062-715-2314
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-15
Band gap tunability of Fe, Co doped Bismuth Lanthanum Titanate thin films
deposited by PLD
H. An1, J. Y. Han2, C. W. Bark2, S. Lee1*
1Materials Science and Engineering, Gwangju Institute of Science and Technology,
Gwangju 500-7122Department of Electrical Engineering, Gachon University, Seongnam 461-701
Tunability of wide band gap in complex oxide is a major issue of the current photovoltaic
research field. Also, the photovoltaic effect for ferroelectric materials has attracted attention due to
effective ability of charge separation and collection. In this research, we have controlled the band
gap of ferroelectric Bi3.25La0.75Ti3O12 thin films through Fe, Co doping. The BLT and Fe, Co doped
BLT epitaxial thin films has been grown on SrTiO3(STO), LaAlO3(LAO) substrates by pulsed laser
deposition (PLD). The structural and optical properties were analyzed by X-ray diffraction,
Ultraviolet-visible absorption spectroscopy. Optical band gap of Fe doped BLT (BLFTO) epitaxial
thin films on STO was decreased from 3.4eV, which is the band gap of BLT, to 2.5eV.
Futhermore, when both Fe and Co were doped in BLT (BLFCTO), optical band gap was more
decreased to 2.05eV. We also observed optical band gap could be reduced depending on substrates,
which might be related with the strain status of thin films due to the lattice mismatch. Thus, by
using simple doping and strain engineering methods, band gap could be tuned easily. Therefore,
these approaches could be applied to energy applications and optoelectronic devices.
*E-mail : [email protected]
Contact Phone : 062-715-2314
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-16
BaZrO3 incorporated Ba(Fe,Co)2As2 multilayer epitaxial thin films
J. Lee1, J. D. Weiss2, J. Jiang2, E. E. Hellstrom2, and S. Lee1*
1School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-7122Florida State University, Tallahassee, FL, US
Since the discovery of iron-based superconductors, epitaxial thin films have been successfully
grown by many groups and they have significantly advanced potential device applications and the
understanding of the fundamental physical properties of these new superconductors. In particular, we
recently have grown artificially engineered undoped BaFe2As2/Co doped BaFe2As2 compositionally
modulated superlattices structures produces ab-aligned nanoparticle arrays and self-assembled c-axis
aligned defects that combine to produce very large Jc and Hirr enhancements. Recently, it has been
reported that BaZrO3 could exist as the nano particle second phase in BaFe2As2 matrix since it is
chemically stable. We incorporated various mol % BaZrO3 in Co doped BaFe2As2 ceramic targets
and have grown BaZrO3 incorporated Co doped BaFe2As2 / undoped BaFe2As2 multilayer epitaxial
thin films by using pulsed laser deposition to maximize the pinning effect in BaFe2As2 system. We
will discuss the structural properties of BaZrO3 incorporated Co doped BaFe2As2 multilayer thin
films examined by X-ray diffraction and the superconducting transition temperature (Tc) and critical
current density (Jc).
*E-mail : [email protected]
Contact Phone : 062-715-2314
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-17
Thermoelectric properties of organic multilayers
Hye Jeong Lee1, Hyeon Jun Lee1, Yong Jae Kim2, Eun Ji Lee2, Jae Yoo Choi3,
Hee Suk Kim3, and Ji Young Jo1*
1 School of Materials Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju 500-712, Republic of Korea. 2 Graduate School of Analytical Science and Technology, Chungnam National University,
79 Daehakro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.3 Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology
(KIST), 14-gil 5 Hwarang-ro, Seongbuk-gu, Seoul 136-791, Republic of Korea.
The high demand for converting natural and waste heat into electrical energy makes thermoelectric
generators attractive energy resources. As compared to inorganic thermoelectric materials, organic
thermoelectric materials, which are flexible, ecofriendly, highly elastic, and cost-effective, are promising
candidates for thermoelectric generators. However, low electrical conductivity and power factor of organic
thermoelectric materials have been obstacles for realization of practical device applications. In this study, we
propose a new strategy for enhancing the electrical conductivity and power factor of organic thermoelectric
materials by fabricating multilayer structure using two different conducting polymers-
Poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and polyaniline doped with
camphorsulfonic acid (PANI-CSA). In the PEDOT:PSS/PANI-CSA multilayer structure, we found that the
multilayer structure for PEDOT:PSS/PANI-CSA enhances the conductivity as well as power factor in
comparison with PEDOT:PSS thin films due to charge diffusion from PANI-CSA to PEDOT:PSS and 2
dimensionional carrier movement.
At first, PANI-CSA film was deposited on the glass substrate followed by annealing at 50 for 1 hr
in N2 ambience. PEDOT:PSS film was deposited on top of the PANI-CSA film and then baked at 120
for 15 min in N2 atmosphere. The sample was immersed in DMSO for 20 min at 60 in air. The above
process was repeated from 1 to 5 times for fabricating multilayer structures, which are labeled as
n(PEDOT:PSS/PANI) with a repetition number n. Thickness of both PANI-CSA and PEDOT:PSS component
layer is around 20 nm, which was confirmed using transmission electron microscopy. We found that the
electrical conductivity and the power factor were increased from 1.1×103 S/cm and 23.92 μWm-1K-2 for
PEDOT:PSS single layer to 1.6×103 S/cm and 48.00 μWm-1K-2, for 5(PEDOT:PSS/PANI) layers, respectively.
Our study suggests that fabrication of multilayers with two different conducting polymers is a promising
technique to enhance the thermoelectric properties of organic materials
*E-mail : [email protected]
Contact Phone : 062-715-3215
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-18
Ferroelectric Properties of PMT-PT ceramics modified with Bi2O3
G. B. Kim*
1Department of Applied Physics, Dankook University, Yongin 448-701
Ceramics samples of 0.65Pb(Mg1/3Ta2/3)O3-0.35PbTiO3 modified with Bi2O3 were prepared using
the columbite precursor method. Lead magnesium tantalate (PMT) is has an anomalously large
dielectric constant and a broad diffuse phase transition near -98 . On the other hand, lead
titanate (PT) is a normal ferroelectric exhibiting a sharp peak in dielectric constant and its Curie
temperatrue is about 490 . Ceramics samples of 0.65PMT-0.35PT closed to the morphotropic
phase boundary (MPB) was chosen in the resent work. The optimum conditions for obtaining
samples with high density and improved electric properties were the addition of 0.3 wt% Bi2O3.
The temperature dependent dielectric constant of the samples was measured as frequencies ranging
from 1 kHz to 100 kHz. The dielectric constant showed a broad maximum value in all
compositions. All the samples exhibited for the frequency dispersion behavior of the dielectric
constant. It is a characteristic of relaxor ferroelectrics. The pyroelectric coefficient and spontaneous
polarization were measured as temperature function. The composition with maximum pyroelectric
coefficient corresponds to the composition with maximum dielectric constant. The maximum
pyroelectric coefficient increased with increasing amounts of Bi2O3 up to 0.3wt% and thereafter
decreased up to 1.0wt%. The pyroelectric peak temperature is shifted to lower temperature with the
addtion of small amounts of Bi2O3.
*E-mail : [email protected]
Contact Phone : 031-8005-3220
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-19
Thermal Annealing Effects of Zn1-xLixO Grwon by So-Gel Method
J. W. Hyun*, G. B. Kim, J. H. Lee
1Department of Applied Physics, Dankook University, Yongin 448-701
Li-doped and axis orientated ZnO films that have useful optical and electrical properties
can be fabricated by the sol–gel method. The pure and Li-doped ZnO films were prepared by
the sol–gel process using zinc acetate dihydrate as a precursor, diethanolamine as a catalyst,
and lithium acetate dihydrate as a doping source. Films of Zn1-xLixO on Pt (Pt/Ti/SiO2/Si)
and Si substrates were annealed at various temperatures, and the effect of annealing on the
structural and optical properties of the films were studied. The Zn1-xLixO films on a Pt
substrate, which was annealed at 700℃ were also doped with various concentrations of
lithium acetate dihydrate, and the dielectric properties were measured. While highly c-axis
oriented ZnO films were successfully obtained on a Pt substrate, the ZnO film on a Si
substrate had a polycrystalline structure.
The optimal annealing temperature for the Zn0.99Li0.01O film on a Si substrate was also 700℃.
Phases of SiO2 and lithium silicate were also observed in Zn0.99Li0.01O films at annealing
temperatures of 800℃ and 900℃, respectively. When Zn1-xLixO films on Si and Pt substrates were
annealed at 700℃. The films with dopant concentrations of x= 0.2 and 0.5 were easily peeled off
from the substrates. In particular, the PtLi2O3 phase was observed in the Zn1-xLixO film on a Pt
substrate with the Li-doping concentration above x= 0.15. The PtLi2O3 phase resulted from the
reaction between the substrate (Pt) and the dopant (Li). The maximum remanent polarization of
0.25 μC/cm2 and the maximum dielectric constant of 18.01 were obtained for the Zn0.85Li0.15O film
on a Pt wafer.
*E-mail : [email protected]
Contact Phone : 031-8005-3220
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-20
Admittance Spectroscopy of the PbSc1/2Nb1/2O3 Polycrystalline Relaxor
Y. J. Kim*
General Education Center, Dankook University, Yongin 448-701
Complex admittance of PbSc1/2Nb1/2O3 as a function of temperature and frequency were
measured. The admittance spectroscopy of PbSc1/2Nb1/2O3 polycrystalline relaxor is in agreement
with broad distribution of relaxation phenomenon such as space charge and dipoles. Before Tm,
resonant frequency decreases with increasing temperature, on the other hand after Tm, resonant
frequency increases with increasing temperature. In addition, maximum admittance Y'(G) and
susceptance Y''(B) increase with increasing temperature. Strong frequency dependent of dielectric
constant is observed at temperatures near and below the Tm than at those above Tm. Moreover, the
nature of transition in the PbSc1/2Nb1/2O3 is suggested by the obvious thermal hysteresis between
heating and cooling dielectric constant curves. The value of critical exponent γ=1.15 and γ=1.61
showed an on cooling and heating treatments, respectively, indicating a broadened phase transition
for PbSc1/2Nb1/2O3 relaxor.
*E-mail : [email protected]
Contact Phone : 031-8005-3764
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-21
Effect of sintering temperature on electrical properties of Lead-free
(K0.5Na0.5)0.75Ag0.25NbO3 ceramics
J. D. Byun1, Y. J. Kim2 and J. W. Hyun1*
1Department of Applied Physics, Dankook University, Yongin 448-701, Korea2General Education Center, Dankook University, Yongin 448-701, Korea
In this research, the lead-free ferroelectric ceramics (K0.5Na0.5)0.75Ag0.25NbO3 has been prepared
by using solid-state synthesis. The effect of sintering temperature on electrical properties and
structural of (K0.5Na0.5)0.75Ag0.25NbO3 ceramics were studied. The mixed powder was sintered at 1100
~ 1150 for 4 hours after calcining at 800 for 3 hours. The temperature dependent of
dielectric constant in the (K0.5Na0.5)0.75Ag0.25NbO3 was measured at various frequencies. The
maximum dielectric constant (Kmax) depends on sintering temperature. The Kmax, from 7699 down to
4505 at various sintered samples. The maximum dielectric constant was 7699 at 326 in 1110
sintered sample. The surface morphology was measured by using field-emission scanning electron
microscopy and the crystal phase was examined by using X-ray diffraction.
*E-mail : [email protected]
Contact Phone : 031-8005-3220
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-22
Highly Durable Ti-mesh Based Triboelectric Nanogenerator for Self-Powered
Device Application
Ermias Libnedengel Tsege1, Dong-Myeong Shin1, Seunghun Lee2, Hyung-Kook Kim1,*
and Yoon Hwae Hwang1,*
1 Department of Nanomaterials Engineering & BK21 Plus Nanoconvergence Technology
Division,Pusanational University (PU), Miryang 627-706, Republic of Korea2 The Institute of Basic Science, Korea University, Seoul, 136-713, Republic of Korea
We developed a highly durable Ti-mesh based triboelectric nanogenerator(Ti-TENG) with
sandwiched structure to harvest electrical energy from contact electrification. The electrical output
from the fabricated Ti-TENG via compressing and releasing strain was measured under different
applied loads and frequencies. The Ti-TENG could generate a peak voltage and current up to ~1.1
V and ~14 nA at an applied force of 30N and frequency of 1.1Hz. The obtained potential was
used to charge a capacitor and light up a commercially available LED. In particular, the Ti-TENG
which exhibited high electrical stability can be used in applications where high robustness and
durability are demanded. For instance, the Ti-TENG was applied as walking step counter by
detecting the motion of the person’s shoe, showing its capability to serve as a self-powered devices.
Therefore, we believe our device can provides a highly promising platform with superior robustness
and durability for applications of self-powered devices to effectively harvest energy from mechanical
movement.
*E-mail :[email protected] (H.-K. Kim), [email protected] (Y.-H. Hwang)
Contact Phone : Tel: +82-55-350-5271 (H.K. Kim), +82-55-350-5274 (Y.-H. Hwang)
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-23
Thermal Conductivity and Interfacial Thermal Resistance
of Gd2Zr2O7 Thin Films
J. H. Kwak , J. G. Kang, and H. S. Yang*
Department of Physics, Pusan National University, Busan 609-785
Gd2Zr2O7, rare-earth zirconates, has been known as a promising candidate for future thermal
barrier coating materials. Gd2Zr2O7 forms in the pyrochlore structure which is similar to the fluorite
structure with 1/8 oxygen missing which results in low thermal conductivity.
Gd2Zr2O7 films are deposited on the Al2O3 substrate as varying film thickness from 105 nm to
663 nm by using RF magnetron sputtering. The structural crystallization, surface roughness, and
thickness of the thin films are characterized with X-ray diffraction, atomic force microscopy, and
scanning electron microscopy, respectively. Thermal conductivity is measured at various temperatures
from 80 K to 298 K by using the 3ω method. Thermal conductivity of Gd2Zr2O7 films exhibit film
thickness dependence and this result is understood with the interfacial thermal resistance between
thin film and substrate.
*E-mail : [email protected]
Contact Phone : 051-510-2221
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-24
Graphene oxide-stimulated myogenic differentiation of C2C12 skeletal
myoblasts
J. H. Lee, M. J. Kim, Y. C. Shin, S. E. Kim, J. S. Kim, J. H. Park and D. -W. Han*
Department of Cogno-Mechatronics Engineering & BK21+ Nano-Integrated
Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735
Graphene, a single layer sheet of sp2-hybridized carbon atoms, has a crystal lattice structure.
Graphene oxide (GO), which is synthesized by oxidization of graphene, has been studied for
biomedical applications, such as drug delivery systems, cell imaging and biosensors, because of its
excellent biocompatibility and physicochemical properties. Many studies have been evaluated the
effect of GO on cell behaviors, including cell attachment, proliferation and differentiation. However,
the effect of GO particles on myoblasts has not been fully revealed yet. In this study, we
investigated the effects of GO particles on C2C12 skeletal myoblasts. The physicochemical
properties of GO particles were characterized by Raman spectroscopy and atomic force microscopy
(AFM). In addition, we evaluated the cytotoxicity of GO particles on C2C12 myoblasts by
measuring the cell viability in growth media containing different concentrations (0 500 ppm) of
GO particles. The viability of myoblasts was determined by using WST-8 assay. Furthermore, we
analysed the myogenic differentiation of myoblasts by immunofluorescence staining for myosin
heavy chains (MHCs), which is a myogenic differentiation marker. It is revealed that the GO did
not exhibit the cytotoxicity at low concentrations ( 30 ppm) and could stimulate the myogenic
differentiation of C2C12 myoblasts. In conclusion, it is suggested that the GO can be used as a
novel biomaterial for skeletal tissue engineering by enhancing cell behaviors.
*E-mail : [email protected]
Contact Phone : 051-930-7725
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-25
Structures and optical studies of the rare-earth-doped Ca5(PO4)3Cl powders
김영경1, 양호순1, 홍경수2
1 부산대학교 물리학과
2 한국기초과학지원연구원 부산센터
Apatite groups constitutes the most of the phosphorus on the Earth. Minerals of the
apatite groups are the main raw materials in the production of phosphorus fertilizers, fodder
and technical phosphates, elementary phosphorus, and phosphor- organic compounds. The
fluorescent features of apatites have several applications, such as detection and identification
of minerals in rocks and ores. The composition of apatite has the general formula
Ca5(PO4)3(F,Cl,OH,O). Since the rare-earth elements substituted for the calcium sites of
apatites become the luminescence centers in a crystallographic environment, the optical features
of apatites are interesting subjects for the phosphor applications.
We prepare Eu3+- and Sm3+-doped calcium chlorapatite [Ca5(PO4)3Cl] powders by using
the solid-state reaction method sintering at 1,100 oC and 1,300 oC, respectively. We
characterize the structures of the synthesized powders by using an X-ray diffractomer, examine
the morphology by using a scanning electron microscope, and the chemical bonding states by
using an X-ray photoelectron spectrometer. We study photophysical properties of the
synthesized apatites by taking absorption, excitation, and emission spectra at room temperature.
We find that apatites with Eu3+ are red-emitting phosphors and have higher efficiency for the
operation with the NUV excitation, while those with Sm3+ are efficient red-orange-emitting
materials.
*E-mail : [email protected]
Contact Phone : 051-974-6106
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-26
Structural phase transition and polarization analysis of non-centrosymmetry
phases in BiOIO3
Nayoung Song and Bog G. Kim*
Department of Physics, Pusan National University, Busan 609-785, South Korea
최근 들어 non-centrosymmetric phase 에 관한 다양한 계산 혹은 실험 결과들이 소개 되고
있다. 우리는 본 발표 논문에서 Bi3+ 와 I5+ 를 포함하고 있는 새로운 물질 (BiOIO3)에서의
non-centrosymmetric phase 에 관한 계산결과를 발표하고자 한다.
우리는 밀도 범함수를 사용하는 VASP을 이용하여, 구조적인 상변화와 자발 분극의 크기
에 관한 계산을 수행하였다. 최근 실험 결과에서 보듯이 본 물질은 상온에서 orthorhombic 구
조를 가지고 있다. 아주 높은 온도에서는 tetragonal 상이 안정된 구조로 생각되어지나 그 에너
지 차이에 의해 낮은 온도에서는 tetragonal 상에 관해서는 관측이 되지 못한다. 우리의 계산결
과로 이러한 에너지에 관한 논의가 보다 정량적으로 접근이 가능하다. 또한 tetragonal 상에서
orthorhombic 상으로의 상전이에 관한 분석을 그룹이론과 모드 분석을 통해 해 봄으로 인해,
산소 사면체의 비틀림이 상전이의 중요한 원인임을 제시하고자 한다. 또한 비선형 광학 상수
에 관한 계산결과도 논의하고자 한다.
*E-mail : [email protected]
Contact Phone : 051-510-3595
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-27
First Principles Study on the Structural Stability between TiO2 Rutile and TiO2
Anatase
K. S. Choi1* and C. H. Park2
1Department of Physics, Pusan National University, Busan 609-7852Research Center for Dielectric and Advanced Matter Physics, Department of Physics
Education, Pusan National University, Busan 609-785
The electronic structure and the structural stability between TiO2 Rutile and TiO2 Anatase was
investigated through the first Principle calculation based on Density Functional Theory. Specially we
focused on the band alignment between two polytypes. The LDA+U method was applied for the
comparison of the electronic structure and the total energy. We tried to understand the structural
rearrangement between Anatase and Rutile with respect of the Ti-3d and O-2p hybridization.
*E-mail : [email protected]
Contact Phone : 051-510-3399
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-28
Microwave Tunable Properties of CPW Phase Shifter Based on Barium
Stannate Titanate Thin Films
H. C. Ryu1* and S. J. Lee2
1Department of Car Mechatronics, Sahmyook University, Seoul 139-742, Korea2Component & Materials Research Laboratory, Electronics and Telecommunications
Research Institute, Daejeon, 305-350, Korea
Barium stannate titanate (Ba(Ti1-x,Snx)O3, denoted as BTS) thin films were deposited on MgO
substrate using pulsed laser deposition. The crystalline structure properties of BTS were investigated
by X-ray diffractometer; the thickness of the films were investigated using a scanning electron
microscope. Tunable dielectric properties of BTS thin films were measured using interdigitated
(IDT) capacitor structure and coplanar waveguide (CPW) phase shifter at room temperature. IDT
capacitor based on an epitaxial BTS film exhibited the large capacitance tunability of 82 % at a
frequency of 100 kHz and applied voltage of 40 V. And the CPW phase shifter showed a large
differential phase shift of 220 ° at 35 GHz and applied voltage of 40 V. These results indicate that
the thin BTS film can be used for the highly efficient microwave tunable devices.
*E-mail : [email protected]
Contact Phone : 02-3399-1801
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-29
One-dimensional hematite nanostructures for photoelectrochemical water splitting
Do Hong Kim1,2, Young-Seok Shim1, Moon Cheon Woo1, Koo Tak Hong1, Jong-Myeong
Jeon1, Yeon Hoo Kim1, Ki Chang Kwon1, Jun Min Suh1, Dinsefa Mensur1, Jong-Heun Lee2,
and Ho Won Jang1*
1Department of Materials Science and Engineering, Seoul National University, Seoul
151-744, Korea2Department of Materials Science and Engineering, Korea University, Seoul 136-361,
Korea
Hematite has recently stimulated increasing attention because of their promising applications in
fields such as solar hydrogen generation by water photoelectolysis. For this application, since the
device performance largely depends on the surface-to-volume ratio of the hematite electrodes or
catalysts, tremendous efforts have been devoted to synthesize hematite nanomaterials with large
specific surface areas.
Among them, one-dimensional hematite nanostrucures have attracted great interest owing to the
facile synthesis of them using anodic oxidation. Highly ordered hematite nanostructures are an
effective design strategy for taking advantage of one-dimensional nanostructures such as high
surface-to-volume ratio and novel functionalities of hematite.
Herein, we report facile synthesis of one-dimensional hematite nanostructures with large specific
surface area for water splitting cells. The obtained efficiency is among the highest reported values
for a hematite based photoelectrochemical cell. This enhancement in the photoconversion efficiency
is related to the unique structural properties of the fabricated porous hematite films. The additional
virtue, the simplicity in the synthesis method, would broaden the applications of the porous
hematite nanostructures to various devices including sensors, batteries, and photochromic glasses.
*E-mail : [email protected]
Contact Phone : 02-880-7092
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-30
A New Approach to the Negative Capacitance of Ferroelectric Thin Films
Y. J. Kim1*, Y. H. Park1, Y. H. Lee1, H. J. Kim1, W. Jeon1, T. Moon1, K. D. Kim1,
D. S. Jeong2, H. Yamada3, and C. S. Hwang1
1Department of Materials Science and Engineering and Inter-university Semiconductor
Research Center, College of Engineering, Seoul National University, Seoul 151-744,
Korea. 2Electronic Materials Center, Korea Institute of Science and Technology, Hwarangno
14-gil 5, Seongbuk-gu, 136-791 Seoul, Republic of Korea.3National Institute of Advanced Industrial Science and Technology (AIST) and JST,
PRESTO, Higashi 1-1-1, Tsukuba, Ibaraki 305-8562, Japan.
Enhancement of capacitance by the negative capacitance effect in dielectric/ferroelectric (DE/FE)
stacked film is gaining a greater interest as a feasible solution to solve insufficient charge problems
of miniaturized capacitors and field effect transistors for future semiconductor devices. Since its first
model suggested by Salahuddin and Datta in 2008,[1] showing the strong polarization coupling
between the DE and FE layers, several remarkable experimental proofs on the capacitance boost of
DE layer when FE layer was stacked on top were reported. However, the quantitative theoretical
background of this intriguing effect that has been proposed by the aforementioned authors holds a
self-contradictory problem, and therefore needs an alternative theoretical approach. In addition, the
Landau-Ginzburg-Devonshire type energy function cannot be applied to describe thermodynamical
feature of low dielectric constant DE layers. Therefore, this work suggests a conceptually
straightforward model to describe the energy of DE/FE system which could calculate the
capacitance boost effect quantitatively. The model was applied to all perovskite systems, such as
SrTiO3/BaTiO3, as well as to a system containing conventional DE layer of Al2O3. The model also
calculated the electrical influence of the trapped charge on the DE/FE interface, which was hardly
adopted in the previous model, and the results were compared with the experimental polarization-
voltage curve of amorphous-Al2O3/epitaxial-BaTiO3 layer grown on epitaxial-SrRuO3/DyScO3 single
crystal.
[1] S. Salahuddin, S. Datta, Nano Lett. 8, 405-410 (2008)
*E-mail : [email protected]
Contact Phone : 02-880-8923
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-31
Study on the wake-up phenomenon of ferroelectric Hf0.5Zr0.5O2 thin films by
polarization switching and discharge behavior
H. J. Kim*, M. H. Park, Y. J. Kim, T. Moon, K. D. Kim,
Y. H. Lee, and C. S. Hwang
Department of Material Science & Engineering and Inter-university Semiconductor
Research Center, Seoul National University, Seoul 151-744, Korea
Recently, it was reported that thin HfO2 films can show ferroelectric properties when doped
with various dopants such as Zr, Si, Y, Al, Gd, La and Sr. It is generally accepted that the
ferroelectricity within these materials originate from the formation of non-centrosymmetric Pca21
orthorhombic phase.[1] The feasible ferroelectricity (remanent polarization >20μC/cm2) with
extremely small thickness (<10nm) is considered highly promising for various applications.
Surprisingly, the ferroelectric HfO2 films show wake-up phenomenon with increase of the remanent
polarization up to certain number (~105) of electric field cycles. Zhou et al. reported that such
wake-up phenomena of ferroelectric HfO2 films are induced by redistribution of defects, such as
oxygen vacancies, which exist near top and bottom electrode.[2] However, it is quite difficult to
investigate their microstructure transition during electric field cycling. In this study, the wake-up
phenomenon of ferroelectric Hf0.5Zr0.5O2 thin films is analyzed by pulse switching measurement.
Using these methods, the capacitance of electrode-ferroelectric interface and contact resistance could
be obtained from transient switching current curve. In our result, only interfacial capacitance is 2~3
times increased with arising wake-up phenomenon. It suggests that the non-switching interfacial
layer with low dielectric constant is partly changed into switching layer possibly due to the
redistribution of defects such as oxygen vacancies.
[1] J. Muller, et al., Nano Lett. 12, 4318 (2012)
[2] D. Zhou, et al., Appl. Phys. Lett. 103, 192904 (2013)
*E-mail : [email protected]
Contact Phone : 02-880-8923
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-32
Photoactivity of Nanocrystalline Bismuth Vanadate Photoanodes Prepared by
Anodic Electrodeposition
Migyoung Lee1*, Hoon Kee Park1, Seonyong Lee1, Seokhoon Choi1, Jaeho Choi1,
Byung Suh Han1, Boreum Lee1, Seo Yun Park1, H. W. Jang1
1*Oxide Nanostructures & Nanoelectronics Laboratory, Department of Materials Science
& Engineering, Seoul National University, Seoul, KOREA
Bismuth vanadate (BiVO4) is a promising photoanode material for the oxidation of water, but
this material has disadvantages such as excessive electron-hole recombination, poor charge transport.
So in this study, we improved the property of BiVO4 by controlling various parameters.
Nanocrystalline BiVO4 films were synthesized by simple anodic electrodeposition under mildly
acidic condition. The deposition mechanism involved oxidation of V5+ ions to V6+ ions and
precipitated out with Bi ions to form amorphous BiVO4 films on the FTO. The as-deposited films
were then converted to crystalline BiVO4 (monoclinic structure) with yellow color when annealed in
air at 500℃ for 6h. The as-deposited and annealed films were characterized by UV-vis
spectroscopy, X-ray diffraction, and scanning electron microscopy. And the photoactivity of annealed
films was studied by measuring linear sweep voltammetry in solution of 0.1M KH2PO4 with 0.1M
Na2SO3 at pH 6.6 using 3-electrode system. All BiVO4 films were back-illuminated through the
FTO because back-illumination resulted in much higher photocurrent generation, which is often
observed for photoelectrodes with poor conductivity. We adjusted deposition parameters including
the V/Bi ratio, time, voltage and annealing condition. The BiVO4 photoelectrodes by preparing
under the best condition had result that 0.8mA/cm2 of average photocurrent at 1.23V vs. RHE. We
are going to doping and fabricating heterojunction electrodes to inhance photoactivity of water
oxidation.
*E-mail : [email protected]
Contact Phone : 052-259-1930
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-33
Switchable all oxide capacitor with nm-thick ferroelectric BaTiO3: a direct
evidence for ferroelectric critical thickness
P. Murugavel1,3*, S. R. Lee1,2⧧, Y. J. Shin1,2, Daniel Sando1,2, J.-G. Yoon4
and T. W. Noh1,2
1Centre for Correlated Electron Systems, Institute for Basics Science (IBS), Seoul
151-747, Korea2Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
3Department of Physics, Indian Institute of Technology Madras, Chennai-600036, India4Department of Physics, University of Suwon, Hwaseong, Gyeonggi-do 445-743, Korea
Scaling properties of materials characteristics down to nanoscale are fetching interest in view of
understanding the fundamental physical properties and its application potential such as magnetic
dead layer and ferroelectric critical thickness. Though the ferroelectric oxides are an important class
of advanced materials due to their wide range of application potentials, such scaling issues with
respect to thickness, which degrade device performance, are not completely settled yet. It has been
believed that depolarization field is critical for polarization degradation at nanoscale [1]. Critical
thickness for ferroelectricity has been studied using theoritical methods: for example, 6 unit cell
(uc) for BaTiO3 (BTO) is predicted [1]. Further theoritical study estimated 3 uc of the critical
thickness for BTO by using frozen-phonon calculations [2]. Experimental studies for ferroelectric
scaling properties, however, have been bounded mostly due to difficulties for obtaining high quality
ultrathin ferroelectric films. In a capacitor structure, the reported critical thickness limit is about 3
uc for PbTiO3 using X-ray scattering technique [3]. In our study, we have succeeded in fabricating
ultra-thin ferroelectric BaTiO3 films down to about 1 nm by employing La0.67Sr0.33MnO3 and SrRuO3
as a top and a bottom electrodes, respectively, using piezoresponse force microscopy (PFM). Further
experimental results such as retention will be presented.
References
[1] J. Junquera and Ph. Ghosez, Nature (London) 422, 506 (2003).
[2] G. Gerra, A.K. Tagantsev, N. Setter, and K. Parlinski, Phys. Rev. Lett. 96, 107603 (2006).
[3] D.D. Fong, G.B. Stephenson, S.K. Streiffer, J. A. Eastman, O. Auciello, P.H. Fuoss, C. Thompson,
Science 304, 1650 (2004).
*E-mail : [email protected]
⧧E-mail : [email protected]
Contact Phone : 02-883-1385
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-34
X-ray radiation effects in P(VDF-TrFE) using atomic force microscopy
Owoong Kwon1, Hyeon Jun Lee2, Hosung Seo1, Hye Jeong Lee2, Ji Young Jo2,
Yunseok Kim1*
1School of Advanced Materials Science and Engineering, Sungkyunkwan University,
Suwon 440-746, Republic of Korea2School of Materials Science and Engineering, Gwanju Institute of Science and
Technology, Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
Polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) copolymer has been used in various
applications such as information storage devices and energy harvesting systems due to flexibility
and low processing temperature, etc. There are several studies of radiation effects on the
P(VDF-TrFE) film. It was reported that new phase can be formed by the x-ray irradiation and,
accordingly, ferroelectric property can be changed after the irradiation. We observed similar behavior
in our P(VDF-TrFE) thin films. To explore the influence of the irradiation on the electrical
properties, piezoresponse force microscopy (PFM) and electrostatic force microscopy (EFM) were
used for measuring switching and surface potential behavior, respectively. The hysteresis loop
opening, measured by PFM, of the pristine region is larger than that of the irradiated region. In
addition, we measured EFM at several different frequencies of 1st and 2nd harmonics to observe
surface and internal electrical properties. These results represent that x-ray irradiation makes some
change on the electrical properties in the P(VDF-TrFE) copolymer by phase transition.
*E-mail : [email protected]
Contact Phone : 031-290-7405
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-35
Reaction Pathway of Steam Methane Reforming
on Ni3M (111) (M = Rh, Ru) Surface: A DFT Study
Hanmi Kim1, Jaichan Lee1*
1School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon,
440-746, Republic of Korea
Solid oxide fuel cells (SOFCs) are of great interest, in particular because of their relatively
high fuel flexibility. In addition to anode of the solid oxide fuel cell, nickel has been widely used
as a catalyst for methane dissociation of fueling. In the process, carbon deposition is often
accompanied by the methane dissociation, which causes to deteriorate cell performance of SOFC.
Density functional theory (DFT) was used to investigate the dissociation process of methane on
nickel and doped nickel (111) surfaces. Reaction path of the dissociation to CH3, CH2, CH, C, H
on Ni (111) and Ni3M (111) (M = Rh, Ru) surface was traced by calculating adsorption and
activation energies in each dissociation step. Additionally, the generation mechanism of CO gas was
investigated. The transition states and activation energies were calculated by the nudged elastic band
(NEB) method. Alloying nickel by ruthenium reduces the activation energies of the dissociation into
of CH4, CH3, CH2 and CH while the activation energy of the dissociation of CH is not changed.
The activation energy of the step for CH + O CHO is decreased for ruthenium alloying slab.
This indicates that Ni3Ru is an effective way to enhance the dissociation of methane and reduce
the carbon deposition.
*E-mail : [email protected]
Contact Phone : 031)299-4743
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-36
Frequency dependent electromechanical response for distinguishing different
origins in strain-based atomic force microscopy
Daehee Seol1, Seongjae Park1 and Yunseok Kim1*
1School of Advanced Materials Science and Engineering, Sungkyunkwan University (skku),
Suwon, 440-746, Republic of Korea
Strain-based atomic force microscopy (s-AFM) techniques such as piezoresponse force
microscopy (PFM) and electrochemical strain microscopy (ESM) have been developed for probing
of local electromechanical (EM) response at the nanoscale. However, since origins of EM response
are diverse on the different materials such as ferroelectrics and electrochemical devices, it is
important to investigate their different origins when characteristics of materials is not known.
Recently, Chen et al reported several methods for distinguishing electrochemical response and
piezoresponse1. However, since their approach is based on the harmonics and hysteresis loop
measurements, there is a limitation on its application. In this presentation, we reported frequency
dependent Vac sweep which is a simple method for distinguishing EM response on the
electromechanically active samples. We have chosen Li-ion conductive glass ceramics (LICGC),
composed of ionic and piezoelectric phases, and Pb(Zr,Ti)O3 as model samples. We observed that
EM response caused by ionic motion is increased according to decrease Vac frequency whereas
piezoresponse is not changed. In addition, we observed spatial variation of frequency dependent
ionic and piezoelectric response in the LICGC. There observations show that ionic and piezoelectric
response show different behavior at different frequency regime. These results could provide
additional method to investigate different origins of EM response.
References
[1] Q. N. Chen, Y. Ou, f, Ma and J. Li, Appl. Phys. Lett. 104, 242907 (2014)
*E-mail : [email protected]
Contact Phone : 031-290-7413
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-37
Homoepitaxial single- and poly-crystalline SrTiO3 thin films
Sungmin Woo1, Hoidong Jeong1, Sang A Lee1,2, Hosung Seo3, Morgane Lacotte4, Adrian
David4, Hyun You Kim5, Wilfrid Prellier4, Yunseok Kim3, WooSeokChoi1*
1Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea2Insitute of Basic Science, Sungkyunkwan University, Suwon, 440-746, Korea
3School of Advanced Materials Science and Engineering, Sungkyunkwan University,
Suwon, 440-746, Korea4Laboratorie CRISMAT, CNRS UMR 6508, ENSICAEN, Normandie Universite, 6 Bd
Marechal Juin, F-14050 Caen Cedex 4, France5Department of Nanomaterials Engineering, Chungnam National University, Daejeon,
305-764, Koreaysics, Pusan National University, Busan 609-785
Studying poly-crystalline transition metal oxides (TMOs) in comparison to the single-crystals,
provide various intriguing physical insight to the materials system. In particular, electronic and ionic
conduction at the grain boundaries, phonon propagation, and various domain properties can be
assessed through an accurate comparison between the two crystal structures. Here we propose an
approach to simultaneously fabricate both single- and poly-crystalline epitaxial TMO thin films on
SrTiO3 substrates. In order to grow TMO thin films epitaxially with atomic precision, an atomically
flat surface of the substrate is a prerequisite. We examined various single- and poly-crystalline
SrTiO3 surfaces, which required different annealing conditions for atomically flat surfaces. By
considering the surface energy of the domains with different crystallographic orientations, we
successfully prepared atomically flat poly-crystalline SrTiO3 surface. We then fabricated
homoepitaxial single- and poly-crystalline SrTiO3 thin films by controlling the elemental vacancies
in the film. The comparison between the crystal structures offers interesting physical aspects
regarding TMO domains and grainboundaries.
*E-mail : [email protected]
Contact Phone : 031-290-5903
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-38
Crystal and electronic structure of homoepitaxial SrTiO3 thin films with
elemental vacancies
Sang A Lee1, Hoidong Jeong1, Sung Min Woo1, Jae-Yeol Hwang2, Seul Ki Roh1,
Jung Seek Hwang1, Sung Wng Kim2,3, and Woo Seok Choi*,1,2
1Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea2IBS Center for Integrated Nanostructure Physics, Sungkyunkwan University, Suwon
440-746, Republic of Korea3Department of Energy Sciences, Sungkyunkwan University, Suwon 440-746, Korea
Perovskite strontium titanate (SrTiO3, STO) has attracted attention owing to its large dielectric
constant, good insulating property and high chemical stability. It is also one of the most popular
substrates for epitaxial growth of perovskite transition metal oxide thin films and heterostructures. It
is well-known that elemental defects such as oxygen vacancies induce changes in the crystal and
electronic structure of the material. For example, oxygen vacancies induce metallic, and further
more, superconducting state in STO. In this presentation, we have systematically investigated the
formation and the role of elemental vacancies in STO homoepitaxial thin films. We used pulsed
laser epitaxy (PLE) in order to grow homoepitaxial STO thin films under various oxygen partial
pressure from 10-6 to 10-1 Torr to control the amount of elemental defects in the thin films. We
separately identified the role of oxygen and Sr vacancies in the homoepitaxial STO thin films.
While oxygen vacancies were responsible for the metallic behavior of the film, lattice expansion
was mainly due to the Sr vacancies induced with the oxygen vacancies. In addition, while the
oxygen partial pressure and the flow rate of the oxygen in the chamber was critical in determining
the oxygen vacancies in the sample, the shape of the plume (dynamics of the plume) was
responsible for inducing the Sr vacancies.
*E-mail : [email protected]
Contact Phone : 031-299-4945
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-39
Enhanced Photon Absorption of Titanate Nanosheets
Bongwook Chung1, Minoru Osada2 and Jaichan Lee1*
1School of Advanced Materials Science and Engineering, Sungkyunkwan University,
Suwon 440-746, Republic of Korea2International Center for Materials Nanoarchitectonics (MANA), National Institute of
Materials Science (NIMS), Tsukuba 305-0044, Japan
TiO2 has been extensively studied for photocatalyst application. Pure TiO2 has low light
absorption since it has a large band gap, 3.2 eV. To absorb long wavelength light more efficiently,
chemical doping have been used to reduce band gap. However, the reduced band gap decreases the
driving forces of photocatalytic oxidation and reduction reactions, resulting in reduced photocatalytic
efficiency. To keep the high driving forces as well as to absorb long wavelength light, we studied
two dimensional TiO2 nanosheets which has a wider band gap than bulk one due to quantum
confinement effect. The TiO2 nanosheets are codoped by transition metal and halide ions.
GGA-PBE+U scheme was used in this study. We found an intermediate state in the Fe-F or Co-F
codoped TiO2 nanosheets. The intermediate state allows the long wave light absorption through
successive absorptions: from VBM to the intermediate state and from intermediate state to CBM.
This intermediate band enables TiO2 nanosheets to absorb long wavelength light while keeping the
wide band gap. We propose that this intermediate band of codoped nanosheets enhances the
photocatalytic efficiency via the band structure modification.
*E-mail : [email protected]
Contact Phone : 031)299-4743
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-40
Tailoring of Electron-Phonon Coupling in Artificially Designed Superlattice
Minsu Choi1, Taejun Hwang1, Jiwon Seo1, Tran Min Dao1 and Jaichan Lee1*
1School of Advanced Materials Science and Engineering, Sungkyunkwan University,
Suwon, 440-746, Republic of Korea
We design artificial superlattices to tune the degree of distortion of octahedron and investigate
the function of the distortion on the electrical properties. (La0.75Sr0.25VO3)2/(LaVO3)2n with n = 1, 2,
3, 4, and 5 superlattices were grown on stepped LaAlO3 (001) single crystal substrate using pulsed
laser deposition method. The reflection high energy electron diffraction oscillations and atomic force
microscopy images confirm two dimensional layer-by-layer growths in the films. Both DC and AC
electrical properties of (La0.75Sr0.25VO3)2/(LaVO3)2n superlattices were investigated by 4-point probe
method. The results demonstrate that electron-phonon coupling can be tuned by periodicity of
artificial vanadate superlattice. By controlling V-O-V bond angle mismatch at interfaces between
La0.75Sr0.25VO3 with little VO6 octahedron distortion and LaVO3 with larger distortion, we manipulate
the strength of electron-phonon coupling. Our findings suggest a new way to control of their
coupling in a situation that control over the coupling is still lacking despite marvelous advance in
engineering nanostructures.
*E-mail : [email protected]
Contact Phone : 031)299-4743
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-41
Surface sulfurization of laser-ablated WO3 films for solar water splitting
Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee and Taekjib Choi*
1Hybrid Materials Research Center and Department of Nanotechnology and Advanced
Materials Engineering, Sejong University, 143-747
Solar water splitting to hydrogen and oxygen over a semiconductor is a promising process of
clean and sustainable energy production. Among metal oxides, WO3 is one of relatively smaller
band gap semiconductors, which is highly attractive for electrochromic, photochromic, and
photocatalytic applications. WO3 is also a active material of photoelectrode for the water splitting,
because of its proper band gap to absorb blue part of visible light and the ultraviolet region in the
solar spectrum. WS2 has received much interest in solar water splitting owing to excellent hydrogen
evolution reaction. In this study, WO3 thin films was prepared on transparent conducting oxide/glass
substrate by pulsed laser deposition. WO3 nanostructures were optimized for improved
photoelectrochemical performance. WS2/WO3 heterostructure have been fabricated by sulfurization
using chemical vapor deposition. X-ray diffration and Raman analysis showed the formation of
WS2. Solar water splitting characteristics were investigated by 3-electrode cell with I-V curve, cyclic
voltammetry and impendence analysis.
*E-mail : [email protected]
Contact Phone : 02-3408-3871
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-42
Enhanced Photoelectrochemical Properties of Oxide Semiconductor
Heterostructures
Wooyoung Choi, Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee, and Taekjib
Choi*
Hybrid Materials Research Center and Department of Nanotechnology and Advanced
Materials Engineering, Sejong University
TiO2 is a well-known candidate of photoelectrode for photoelectrochemical applications owing
to its low cost and high activity. Especially, TiO2 nanotube based photoelectrodes could also
provide increased surface area for electrochemical reaction. However, the solar energy harvesting of
TiO2 photoelectrodes have been limited to ultraviolet (UV) light. Various strategies, including
surface modification, cocatalysis, and heterostructure have been investigated to enhance
photoelectrochemical performance. In this study, we have utilized the band alignment of
anatase-rutile TiO2 and heterojunctions of BiFeO3 and TiO2. The band alignments offer the driving
force for the improved photoelectrochemical properties because of the significantly enhanced charge
transport. BiFeO3/TiO2 heterostructures showed the enhanced the visible-light absorption and solar
water splitting. The presence of thin ferroelectric BiFeO3 layer greatly contributed to the enhanced
photovoltaic response by promoting carrier separation due to an increase in the internal field
across heterostructure arising from spontaneous polarization. Therefore, our results provide effective
routes for developing highly efficient photoelectrode based on oxide semiconductor heterostructures.
*E-mail : [email protected]
Contact Phone : 02-3408-3871
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-43
Non-volatile resistive switching effect of LaAlO3/SrTiO3 heterostructures
Sungmoon Hwang1, Yeonsoo Kim2, Baeho Park2 Taekjib Choi1*
1Hybrid Materials Research Center and Department of Nanotechnology and Advanced
Materials Engineering, Sejong University, Seoul, 143-747, Korea 2Division of Quantum Phase & Devices, Department of Physics, Konkuk University,
Seoul 143-701, Korea
The two-dimenstional electron gas (2DEG) at interface between two band insulators LaAlO3
and SrTiO3 has attracted much interest due to its fascinating properties such as high mobility,
ferromagnetism and superconductivity. We have investigated out-of-plane electrical transport of
LaAlO3(LAO)/Nb:SrTiO3 (0.5 w.t.%) (NSTO) structure.
We have deposited LaAlO3 thin film on Nb doped SrTiO3 substrate with various condition by
pulsed laser deposition. Scanning transmission electron microscopy and high-resolution X-ray
diffraction was carried out for investigation of interfacial and crystallographic structure, respectively.
In addition, we have found non-volatile resistive switching behavior through out-of-plane electrical
measurement, which was affected by thickness of LAO layer and the reduction of NSTO surface.
We will also discuss multi-level resistance states with different applied bias and electrical transport
mechanisms.
*E-mail : [email protected]
Contact Phone : 02-3408-3871
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-44
Resistive switching in TiO-SiO composite films after soft breakdown
Tae-Sup Yoo, Chan-Goo Park, and Jong-Gul Yoon*
Department of Physics, University of Suwon, Hwaseong, Gyunggi-do 445-743
여러 비휘발성 메모리 중 MIM (metal-insulator-metal)의 구조를 가진 소자는 산화물과
전극의 특성에 따라 다양한 resistive switching 현상을 보여준다. 하지만 아직까지 이러한
현상에 대한 근본적인 이해와 soft breakdown 등에 대한 여러 부분에서 연구할 것들이 많이
남아있다. 우리는 aerosol-assisted chemical vapor deposition 방법을 이용해 420도에서
Pt/Ti/SiO /Si 기판에 TiO-SiO 혼합 박막을 증착하였으며, 진공 증착기를 이용해 Au 전극을
증착하여 Au/TiO-SiO /Pt 의 구조를 가진 MIM 소자를 만들었다. TiO-SiO의 혼합 비율에
따라 Current - Voltage 특성을 측정하여 전기적 특성을 비교하며, 혼합비율에 따라 달라지는
전기적 특성이 resistive switching 현상에 어떤 변화를 주는지를 확인하고 이러한 변화를
이용해 메모리 정보의 신뢰도와 관련된 on/off 비를 증가시키는데 중점을 두었다. 또한 soft
breakdown을 일으키는 조건을 변화 바꾸면서 resistive switching에 어떤 영향을 주고 이용할 수
있는지 확인해봤다. SiO의 첨가 비율에 따라 on/off 비가 점차 변화하는 것을 확인했으며,
몇몇의 혼합 비율의 박막에서 soft breakdown을 일으키기 위한 전류의 방향에 따라 on/off 비의
차이가 생겼다. 또한 전극의 유무에 따라 soft breakdown 전후에 전기적 특성의 차이도
확인했다. 이것들을 이용해 우리는 on/off 비를 10배 이하에서 약 50배까지 변화시킬 수
있었고 이러한 결과와 원인에 논의해볼 것이다.
*E-mail : [email protected]
Contact Phone : 031-220-2120
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-45
Pt-nanoparticle imbedded ZnO-based thin films for ultra-violet photodetector
Khalkhulin Daniil, Seong-Hoon Kim, Hyuna Im, and Jong-Gul Yoon*
Department of Physics, University of Suwon, Hwaseong, Gyunggi-do 445-743
Metal nanostructures are of great interest for optoelectronic applications because of their
localized-surface-plasmon (LSP) resonance in the presence of external light. In particular, Pt
nanoparticles (NPs) posses a wider tunable LSP energy varying from deep ultraviolet (UV) to
visible region depending on their morphology. The novel properties of the NPs has offered new
opportunities to engineer and improve the performance of optoelectronic devices. In this work, we
investigate the effects of the inclusion of Pt NPs in ZnO-based thin films on its photodetection
performance. ZnO is one of the promising materials for UV photodetectors because of its direct
wide bandgap (3.3 eV), environment friendliness and low cost. We deposit ZnO thin films
embedded with Pt NPs by aerosol-assisted chemical vapor deposition on various substrates. The
current-voltage characteristics of the films under dark and UV illumination conditions are reported.
*E-mail : [email protected]
Contact Phone : 031-220-2120
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-46
Piezoelectric Properties of Bismuth Copper-based Lead-free Ceramics
Achiri Tange, Hee Sung Kim, Chang Won Ahn and Ill Won Kim*
Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Korea
Piezoelectric ceramics are widely used in electromechanical systems due to their good
piezoelectric properties. Lead zirconate titanate (PZT) has been dominant in this respect because it
possesses much superior piezoelectric properties as well as a high Curie temperature near its
morphotropic phase boundary (MPB). Recently due to environmental concerns (because of the
toxicity of lead) there is the need to look for alternative lead-free piezoelectric systems with
properties close to or comparable to that of PZT.
Bismuth copper-based lead-free perovskite materials are interesting because of the effect of
copper in inducing more distortion to the perovskite structure at low fields, thereby improving the
ferroelectric and piezoelectric properties. We have synthesized a lead free piezoelectric material
(1-x)Bi0.5(Na0.78K0.22)0.5TiO3-xCu(Bi0.5Ti0.5)O3 (BNKT-BCuT) using a conventional ceramic process and
studied its physical and piezoelectric properties. The addition of small amounts of BCuT was found
to have a small effect on both the shape of the P-E and S-E hysteresis loops as well as
polarization values. Both the remnant polarization Pr and the coercive field Ec were found to
decrease gradually with increasing BCuT content. The strain was significantly increased for x =
0.01 and decreased monotonically with increasing BCuT content with maximum normalized strain
d33* = 500 pm/V at 50 kV/cm. This suggests that this material (for x = 0.01) could be a
promising candidate for actuator applications.
*E-mail : [email protected]
Contact Phone : 052-259-2323
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-47
Electric Field-Induced Strain of Lead-Free Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 Ceramics
Modified with BaZrO3
T. H. Dinh1, J. K. Kang1, C. H. Lee1, C. D. Park1 Y. H. Hong1 and J. S. Lee1*
1School of Materials Science and Engineering, University of Ulsan 680-749
This study investigated the crystal structure and electric field-induced strain (EFIS) properties of
Bi-rich side of (1-x)[(1-y)Bi0.5Na0.5TiO3 yBi0.5K0.5TiO3]-xBaZrO3(BNT-BKT-BZ)system(x = 0-0.05; y
= 0.14, 0.18, and 0.22). BNT-BKT-BZ ceramics were prepared via conventional method and their
phase structure, microstructure, ferroelectric and EFIS properties were studied. All samples reveal a
relative dense microstructure with pure perovskite structure without any secondary phase. A typical
nonergodic relaxor (NER) behavior was found in (1-y)BNT-yBKT samples with a large remnant
polarization (Pr), large maximum coercive field (Ec), and a typical butterfly shape in the strain
(S-E) curve. With increasing amount of BZ in (1-y)BNT-yBKT system, both Pr and Ec of ceramics
decrease and the P-E loop becomes slimmer close to that of ergodic relaxor (ER) material, that
generally demonstrate a linear P-E loop. The “negative strain” defined as the difference between
zero-field strain and the lowest strain is close to zero and the S-E loop exhibits a drastic deviation
from those of nonergodic relaxor materials. The ternary phase diagram of BNT-BKT-BZ based on
XRD analyses and S-E loop was presented. The largest normalized strain was found to be 640
pm/V at x = 0.3 and y = 0.14, it could be related to the electric field-induced phase transition
between nonergodic relaxor and ergodic relaxor phases under electric fields. It has been also
proposed that the polarization extension from a nonergodic relaxor to an ergodic relaxor phase
under electric fields enhances strain.
*E-mail : [email protected]
Contact Phone : 052-259-2245
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-48
Polar discontinuities and piezoelectric properties of honeycomb lattices
Mohammad Noor-A-Alam and Young-Han Shin*
Department of Physics and EHSRC, University of Ulsan, Ulsan 680 749
Polarity has become an increasingly active research area in the field of oxide surfaces1, where
polar discontinuities drive a metal-insulator transition and the appearance of a two-dimensional
electron gas. Based on first principles calculations, we find that such polar discontinuity in
honeycomb lattices (e.g. graphene, h-BN, and silicene, etc.) is also possible by breaking inversion
symmetry through chemical functionalization2,3. Here we study hydro-fluorinated silicene monolayer
and multilayers. We show that a band gap covering a range from 1.36 eV to 2.15 eV can be
opened in various monolayer configurations. Moreover, piezoelectricity can be engineered into
non-piezoelectric silicene. Our piezoelectric constants are comparable with other known 2D
piezoelectric materials (e.g. hydro-fluorinated graphene/h-BN) and some bulk semiconductors, such as
wurtzite GaN and BN. However, band gap disappears for multilayers because of electronic
reconstruction stemming from uncompensated surfaces charges.
References:
1) C. Noguera and J. Goniakowski, Chem. Rev. 113, 4073 (2013).
2) H. J. Kim, M. N. A. Alam, J. Y. Son, and Y. H. Shin, Chem. Phys. Lett. 603, 62 (2014).
3) M. N. A. Alam, H. J. Kim, and Y. H. Shin, Phys. Chem. Chem. Phys. 16, 6575 (2014).
*E-mail : [email protected]
Contact Phone : 052-259-1027
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-49
Precise measurement of piezoelectric coefficients of PVDF-TrFE films
using a Laser Doppler Vibrometer
Bong Chan Park#, Amir Ullah, Chang Won Ahn and Ill Won Kim*
Department of Physics and Energy Harvest-Storage Research Center,
University of Ulsan, South Korea
The piezoelectric effects in films are being intensively explored for their promising applications
as sensors and actuators in a variety of micro and nano systems. An efficient characterization
technology for the piezoelectric properties of the films, particularly the piezoelectric coefficients, is
becoming more and more essential for both fundamental research and applications. However, the
variation of error among the reported data for piezoelectric films is significantly large amount. The
reason is that no widely accepted standard measurement technique has been popularly used for
films. Some of the measurement methods are not accurate. In this study, we had prepared different
kinds of experimental setup for the determination of the piezoelectric coefficient d33 to improve the
measurement reliability and accuracy and obtained optimization of the experimental conditions using
a Laser Doppler Vibrometer due to its high resolution and advantages of nondestructive
measurement.
The PVDF-TrFE(Poly vinylidene fluoride trifluoroethylene) films were fabricated by sol-gel
processing on Pt/Ti/SiO2/Si substrates and annealing at 140 . The thickness of the films was 2µm.
The films were unclamped with a fixture which was attached to a transition stage on an optical
table. The alternating current driving electrical fields was applied to the PVDF-TrFE piezoelectric
films to stimulate the vibration. A large longitudinal piezoelectric coefficient d33 of PVDF-TrFE film
were obtained 5pm/V at 11kHz without substrate clamping effect. Several key points were discussed
in order to achieve reliable and accurate results.
*E-mail : #[email protected], *[email protected]
Contact Phone : 052-259-1563
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-50
CH3NH3PbI3-xClx 두께 변화에 따른 페로브스카이트 태양전지 효율
Sujung Park, and Shinuk Cho*
Department of Physics and EHSRC, University of ulsan 680-749, South Korea
최근 유기 금속 할로겐화물의 페로브스카이트 구조에 기반을 둔 유-무기 하이브리드 태양
전지가 획기적인 태양전지의 한 기술로써 떠오르고 있다. 페로브스카이트 역구조 태양전지의
간단한 구조와 저온 솔루션 공정 태양전지라는 장점은 저비용으로 고비용의 모폴로지 최적화
필요 없이 소자 제작을 가능하게 한다. 본 연구에서는 CH3NH3PbI3와 CH3NH3PbI3-xClx를 활성
층으로, [6,6]-phenyl-C61- butyricacidmethylester (PCBM) 을 전자 수송 물질이자 정공 차단 물질
로 사용하여 저온 솔루션 공정을 통해 제작 된 페로브스카이트 태양전지에서 페로브스카이트
층과 PCBM 층 계면에서 일어나는 전하 분리를 통해 각 전극으로 전자-정공이 잘 도달하기
위해서는 페로브스카이트 활성 층과 PCBM 전자 수송 층/정공 차단 층의 두께가 소자 효율에
영향을 받으므로 활성 층 두께에 따른 효율 변화를 연구하였다. 활성 층두께에 따른 최적화
조건을 찾음으로써 10.2%의 페로브스카이트 역구조 태양전지 효율을 달성하였다.
*E-mail : [email protected]
Contact Phone : 052-259-1939
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-51
Self-polarization in the a lead-free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric thin
films on Nb:SrTiO3 substrate from interfacial strain relaxation
Hae Jin Seog1, Chang Won Ahn1, Song A Chae1, Kwang-Eun Kim2, Chan-Ho Yang2,
Tae Yeong Koo3 and Ill Won Kim1*
1Department of physics and Energy Harvest-Storage Research Center, University of
Ulsan, Ulsan, 680-749, South Korea2Department of Physics, KAIST, Daejeon, 305-701, South Korea
3Pohang Accelerator Laboratory, Pohang, Gyungbuk, 705-784, South Korea
In recent years, lead-free piezoelectric films have received increasing attention for environmental
protection. The (K,Na)NbO3 (KNN)-based material is a promising lead-free candidate for various
actuators, sensors and transducers in the micro-electro-mechanical systems (MEMS) owing to its
high Curie temperature and excellent piezoelectric properties. However, almost systematic work did
not report in the KNN-based thin films so far except for some studies on (001) preferred
orientation. In this study, the (001) preferred-oriented (K0.5Na0.5)(Mn0.005Nb0.995)O3 (KNMN) thin film
grown on Nb:SrTiO3 (Nb:STO) single-crystalline substrate is used to investigate the spontaneous
self-polarization associated with strain relaxation. It is confirmed that the lattice mismatch between
KNMN thin film and Nb:SrTiO3 substrate creates an interfacial strain gradient, there by producing
strong imprint in a P-E hysteresis loop, i.e., shifting toward ordinate with a distorted shape. The
PFM image exhibited the dark contrast overall in the as-grown state, whereas the bright brown
square area was created by an electric poling at a sample bias of +10 V. The downward
self-polarization of the KNMN thin film occurred by strong inhomogeneous compressive strain due
to strain relaxation. The self-polarization provides a useful insight into self-polarization engineering
by control of strain relaxation and flexoelectricity.
*E-mail : [email protected]
Contact Phone : 052-259-1563
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-52
First-principles study of the effect of oxygen vacancies around the 180°
ferroelectric domain walls of tetragonal PbTiO3
Hoe-Cheol Song, and Young-Han Shin*
1Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Korea
People have extensively studied the dynamics of ferroelectric materials to apply them to
nonvolatile memory devices. One of the critical issues in ferroelectric random access memory is the
fatigue effect, which results from the presence of defect like oxygen vacancy. Many cycles of
polarization switching increase the density of oxygen vacancy around ferroelectric domain walls, and
it makes the ferroelectric energy barrier higher to slow down the switching rate. In this research,
we examine the domain dynamics around the 180° ferroelectric domain walls of tetragonal PbTiO3
with and without the oxygen vacancy by using the first-principles calculations. We estimate the
energy barriers of several possible reaction paths with the nudged elastic band method. Compared
to the oxygen vacancy far away from domain walls, the oxygen vacancy around ferroelectric
domain walls tends to be thermodynamically stable with lower energy barriers. As the density of
oxygen vacancy increases around the domain wall, the energy barrier of domain wall motion
increases. The energy barrier of the oxygen vacancy migration in domain wall system decreases
when it moves with the domain wall, however, the computed value is 0.08 eV higher than vacancy
free case. From this research, we conclude that the oxygen vacancy tends to stay with the domain
wall and make the energy barrier higher, consequently, cause the fatigue effect (reduce the speed of
switching process).
*E-mail : [email protected]
Contact Phone : 052-259-1027
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-53
Piezoelectric P(VDF-TrFE) Thin Film Power Generators on Paper Substrates
for Wearable Device Applications
Sung Sik Won1,2, Nicholas Mostovych2, Angus I. Kingon2, Ill Won Kim1* and
Seung-Hyun Kim2#
1Dept. of Physics and Energy Harvest-Storage Research Center, Univ. of Ulsan, Korea2School of Engineering, Brown University, Providenece, RI02912, USA
The objective of this research is to develop a new class of flexible energy harvesting devices
for self-powered wearable electronic systems. A critical issue of all piezoelectric wearable devices is
the need to reduce the size and the weight so that devices with increased functionality can be
incorporated into a wider range of physiological locations and applications. Use of polymeric
piezoelectric thin films on paper substrates, however, is potentially beneficial for the fabrication of
large-area and complicated-shaped devices with low cost, light weight and size scaling.
In this study, we introduce a new approach for enlarging the sensing capacity and the power
generation of the devices using piezoelectric P(VDF-TrFE) co-polymer thin films coupled with
cellulose paper substrates. Our results demonstrate that with stringent precursor and process control,
excellent ferroelectric and piezoelectric properties of P(VDF-TrFE) thin films can be achieved. In
addition, our suggested flexible paper-based structure shows a high degree of freedom with no
shape limitation and has a good formability, enabling us to cut or shape the devices by using
simple tools such as stamping, punching, or cutting without complex MEMS-based process. Our
P(VDF-TrFE) thin film-based paper power generators are demonstrated to improve power output and
efficiency due to high flexibility, high mechanical compliance, low resonance frequency, and good
piezoelectric response.
*E-mail : #[email protected], *[email protected]
Contact Phone : 052-259-1563
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-54
Low Temperature Sintering of 0.74(Bi0.5Na0.5TiO3)-0.26SrTiO3 Ceramics by
Adding CuO as a Sintering Aid
D. H. Lee1, J. K. Kang1, T. H. Hinh1 and J. S. Lee1*
1School of Materials Science and Engineering, University of Ulsan 680-749
This study investigated the effect of CuO additive on the sintering beahvior and electric
field-induced strain properties of Bi1/2Na1/2TiO3-SrTiO3 (BNT-ST) ceramics. Ceramic specimens were
prepared using a conventional solid-state reaction route. In case of BNT-ST specimen without CuO
aid required sintering temperature (Ts) as high as 1175 oC for sufficient densification, while the Ts
of BNT-ST added with 1 mol% CuO ceramic was lowered down to 1100oC. The unipolar strain of
1 mol% CuO addded specimen reached 550 pm/V under an electric field of 4 kV/mm, which is
promising for low cost multilayer actuator applications.
*E-mail : [email protected]
Contact Phone : 052-259-2245
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-55
Properties of [0.98{Bi1/2(Na0.78K0.22)1/2TiO3}-0.02LaFeO3]-Bi1/2(Na0.82K0.18)1/2TiO3
Lead-Free Piezoceramic Composites
C. H. Hong1*, H. S. Han2, J. S. Lee3, W. Jo1
1School of Materials and Engineering, Ulsan Institute of Science and Technology, Ulsan
689-7982Institute of Materials Science, Technische Universität Darmstadt, Darmstadt 64287
3School of Materials and Engineering, University of Ulsan, Ulsan 680-749
To overcome the challenges that large stains in a Bi-based lead-free piezoelectrics are only
achieved at relatively high electric fields, relaxor (RE)-ferroelectric (FE) ceramic composite concept
was recently proposed as a viable solution1, 2. Here, the relaxor presents the large strain responses,
and the ferroelectric causes the electric field applied to ferroelectric to be intensified locally so that
the driving electric field required for activating large strains can be virtually reduced.
(Bi1/2(Na0.82K0.18)1/2TiO3 (BNKT), 0.98(Bi1/2(Na0.78K0.22)1/2TiO3-0.02LaFeO3 (BNKT2LF) ceramic
powders were synthesized using a conventional solid-state reaction method, and then BNKT2LF was
mixed with BNKT with the composition of 0, 0.1, 0.2, 0.3, 0,5 and 1 mole fractions.
As the BNKT content was increased from 0 to 1 the normalized electric-field-induced strain
(Smax/Emax)was seen to be activated at lower field levels. The best strain property of 500pm/V
was achieved in BNKT2LF-10BNKT at as low as 3kV/mm. The results shows that FE in RE
expedites phase transition of RE to FE at low field, which demonstrates the encouraging potential
of lead-free piezoceramic composites for actuator applications which have low voltage sources such
as mobile devices.
*E-mail : [email protected]
Contact Phone : 010-8814-4155
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-56
Investigation of the local work function distribution and resistance change of
VO2/Al2O3 and VO2/TiO2 thin films spanning the metal-insulator transition
Ahrum Sohn1, TeruoKanki2, Hyun-TakKim3,4, and Dong-WookKim1,*
1Department of Physics, Ewha Womans University, Seoul 120-7502The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
565-0871 3Metal-Insulator Transition Lab., ETRI, Daejeon 305-700
4School of Advanced Device Technology, University of Science and Technology (UST),
Daejeon 305-350
For several decades, numerous researches have investigated intriguing physical properties of
VO2. VO2 undergoes the metal-insulator transition (MIT) and monoclinic-to-tetragonal structural
phase transition (SPT) near the room temperature (~340K). During MIT, the magnitude of the
resistivity change is over 4 orders. In this study, we comparatively studied MIT behaviors of two
kinds of VO2 thin films, which were grown on Al2O3 and TiO2 single crystal substrates. In
particular, we observed their spatial distribution of work function spanning MIT using KPFM
(Kelvin probe force microscopy). The film on the Al2O3 substrate consisted of tiny grains (grain
size: tens of nm) due to large lattice mismatch. On the other hand, the film on the TiO2 substrate
had much larger grains and the MIT temperature is ~300K due to negligibly small lattice
mismatch. KPFM enabled us to reveal the local electronic structure of the sample via its work
function. The work function of the both samples decreased as increasing the sample temperature
above the MIT temperature. In this presentation, we will discuss the influences of the grain size on
the MIT behaviors of VO2 thin films.
*E-mail : [email protected]
Contact Phone : 02-3277-6668
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-57
Structural and electrical properties of epitaxial PbTiO3 thin films on conducting
LaNiO3 grown by laser ablation
H. J. Jin, S. H. Oh, and W. Jo*
Department of Physics, Ewha Womans University, Seoul, 120-750
Ferroelectric PbTiO3 is one of the interesting ferroelectrics showing large spontaneous
polarization of 75 μC/cm2 at room temperature. In this paper, epitaxial PbTiO3 thin films were
deposited on SrTiO3(001) and LaAlO3(001) by laser ablation under various deposition conditions.
With an optimized condition, highly c-axis oriented PbTiO3 thin films were achieved and phase
formation and lattice variation of the thin films were investigated by x-ray diffraction patterns. In
addition, conducting LaNiO3 were used as a bottom electrode to examine electrical properties of
PbTiO3 thin films. To verify local ferroelectric properties and domain transport behaviors of the thin
films, piezoelectric force microscopy and conducting atomic force microscopy was used. From the
microscopic studies, we explored switching characteristics of the c-/a-domains and their charge
conduction over the domain walls which reveals the domain dynamics of ferroelectric materials.
*E-mail : [email protected]
Contact Phone : 02-3277-4066
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-58
Dielectric properties of PIN-PMN-PT Films Prepared by Aerosol-Deposition
Method
S. B. Kang1, Y. M. Kong2, J. H. Ryu3, L. Wang4 and D. Y. Jeong1*
1School of Materials Sci. & Eng., Inha University, Incheon, 402-7512Department of Materials Sci. & Eng., University of Ulsan, Ulsan, 680-749
3Functional Ceramics Group, Korea Institute of Materials Science, Changwon, 641 8314Electronic Materials Research Laboratory, Xi’an Jiaotong University, Xi’an 710049,
People’s Republic of China
PIN-PMN-PT(Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3) is one of the relaxor-PT based
ferroelectric materials.The relaxor-PT based materials revealed low dielectric loss, high dielectric
permittivity and electromechanical properties. As the rhombohedral PIN-PMN-PT has broadened
temperature usage range (rhombohedral tetragonal phase transition temperature, TR-T>120oC), the
ternary PIN-PMN-PT could be applied for capacitors in the electronics, transducers, MEMS and etc.
In this research, We deposited the PIN-PMN-PT thick films by aerosol-deposition (AD) method.
The films deposited by AD method revealed nano-sized grain and dense film structure. The AD
method can fabricate film through the collision of fine ceramic powder particles onto the substrate
at room temperature. The (sub-)micrometer sized particles are crushed nano size, and have strong
adhesion between films and substrate. The films revealed the slim polarization - electric field
hysteresis loop due to the nano-size effect. Through the post annealing process, grain size and
crystallinity can be controlled, resulting in the improvement of the electrical properties of the AD
films. We compared dielectric and ferroelectric properties of the aerosol deposited films. The
ferroelectric properties, the dielectric constant by a change of the frequency were measured using an
impedance analyzer. The polarization - electric field (P-E) hysteresis loops were examined using a
standard ferroelectric test system.
*E-mail : [email protected]
Contact Phone : 010-3756-6023
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-59
A 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 based pyroelectric generator and temperature
sensor
Young Joon Ko, Byung Kil Yun, and Jong Hoon Jung
Department of Physics, Inha University, Incheon 402-751
We report the extremely high pyroelectric power generation of a relaxor ferroelectric
0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3(PMN-PT)single crystal. The pyroelectric current and voltage of
PMN-PT depend on the electric poling voltage, temperature variation rate, and measurement
temperature. Near the structural transition temperatures of the rhombohedral-tetragonal transition
(~380K) and tetragonal-cubic transition (~410K), the temperature induced change of electric
polarization results in the sharp enhancement of pyroelectric power. Near the tetragonal-cubic
transition temperature, i.e. the Curie temperature, we have observed pyroelectric current of ~100 nA
and voltage of ~11 V. Near room temperature, we have observed pyroelectric current of ~1.4 nA
and voltage of ~0.2 V from the touch of a human finger. These results imply that the relaxor
ferroelectric PMN-PT should be quite useful for pyroelectric energy harvesting and temperature
sensing applications.
*E-mail : [email protected]
Contact Phone : 032-874-8776
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-60
Room-temperature hydrogen gas sensing properties of Co3O4/Nb2O5 composite
nanoparticles
S. H. Kim, S. H. Park, H. J. Kheel and C. M. Lee*
Department of Materials Science and Engineering, Inha University, Yonghyun-dong,
Nam-gu, Incheon 402-751, Republic of Korea
Co3O4/Nb2O5 composite nanoparticles were synthesized using a sol-gel process and their H2 gas
sensing properties were examined. The multiple networked composite nanoparticle sensor showed
responses of 137-516 % at 0.01-1.0% of H2 at room temperature. The responses of the composite
nanoparticle sensor to 0.01-1.0% of H2 were stronger than those of the pure Nb2O5 nanoparticle
sensors by 1.1-2.2 times. The former sensor showed faster response than the latter sensor. The
composite nanoparticle sensor showed selectivity for H2 gas over CO, acetone, methane and NH3
gases. The paper discusses the underlying mechanism for the enhanced response, sensing speed and
selectivity of the composite nanoparticle sensor for H2 gas.
*E-mail : [email protected]
Contact Phone : 032-860-7536
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-61
Fabrication, structure and gas sensing properties of Pt- functionalized ZnS
nanowires
S. Park, S. Kim, G. Sun and C. Lee1*
1Department of Materials Science and Enginnering, Inha University, Incheon 402-751
Pt-functionalized ZnS nanowires were synthesized on Au-deposited (0001) sapphire substrates by
thermal evaporation of ZnS powders followed by wet Pt coating and annealing. The NO2 gas
sensing properties of multiple-networked Pt-functionalized ZnS nanowire sensors were examined.
Scanning electron microscopy showed the nanowires with diameters ranging from 20 nm to 80 nm.
The diameters of the Pt nanoparticles on the surfaces of the ZnS nanowires ranged from 20-50 nm.
Transmission electron microscopy and X-ray diffraction showed that the nanowires were
wurtzite-structured ZnS single crystals. The Pt-functionalized ZnS nanowire sensors showed enhanced
sensing performance to NO2 gas at 150oC compared to pristine ZnS nanowire sensors. Pristine and
Pt-functionalized ZnS nanowire sensors showed responses of 140 211% and 207 - 488%,
respectively, to 1-5 ppm NO2 at 150°C, which are comparable to or better than those of many
oxide semiconductor sensors. This results support a possibility of practical use of Pt-functionalized
ZnS nanowires as a sensor for NO2 gas detection. Inaddition, the underlying mechanism of the
enhanced sensing properties of the Pt-functionalized ZnS nanowires is discussed.
*E-mail : [email protected]
Contact Phone : 032-860-7536
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-62
Electric polarization and diode-like conduction in hydrothermally grown
BiFeO3 thin films
T. K. Lee and J. H. Jung
Department of Physics, Inha University, Incheon 402-751
We report the successful synthesis of high-quality BiFeO3 thin films on a SrRuO3/SrTiO3
substrate using hydrothermal methods, and their structural, ferroelectric, and electrical properties.
Using alow precursor concentration, we obtained compressively strained BiFeO3 thin films
(thickness: 60 nm) with smooth surface (roughness: 4.2 nm). The ferroelectric polarization of the
BFO thin films was parallel with respect to the normal to the substrate and changed direction by
180o under the application of electric field. The current flowed unidirectionally; such rectifying
behavior was attributed to Schottky barrier modulation by oxygen vacancies and ferroelectric
polarization. Our results provide an important step in the applications of hydrothermally grown
BiFeO3 thin films like a large-area and low-cost photovoltaic device.
*E-mail : [email protected], [email protected]
Contact Phone : 032-874-8776
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-63
Electrical Properties of Polyvinyldene-fluoride-ZnO Modified CNT
Nanocomposite Film by Spray coating
J. H. Lim1, J. k. Lee1, H. J. Kim1, I. J. No2, Y. M. Kong3, and D. Y. Jeong1*
1School of Materials Science and Engineering, Inha University, Incheon 402-751, Korea2School of Electrical Engineering, Inha University, Incheon 402-751, Korea
3Department of Materials Sci. & Eng. University of Ulsan, Ulsan, 680-749, Korea
The β -phase Polyvinyldene fluoride (PVDF), a typical polymer ferroelectrics, has been widely
studied due to its high dielectric constant, superior piezoelectric and electrocaloric effect compared
to other polymers. The PVDF has four different crystal structures: α-phase; β-phase; γ-phase; δ
-phase. Because of the significant piezoelectric property in the β-phase PVDF film, the β-phase of
PVDF film is very important at the application of actuator. Therefore the researches to make the β
-phase have been carried out. The β-phase PVDF film was usually fabricated by stretching along
the length direction or poling process. It was known that PVDF can be made to poled state by and
during spray coating process without appling the electric field.
In this work, the PVDF films were fabricated by spray-coating method. A ZnO modified
Carbon nanotube (CNT) was included as a additive into the PVDF solution to change electrical
properties. For comparison, the PVDF and CNT nanocomposite PVDF films were also fabricated
by spray-coating process.
*E-mail : [email protected]
Contact Phone : 052-259-1930
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-64
Synthesis of Homogeneous Nanocrystalline LiFePO4 by Two Step Polyol
Process and Their Performance
S. J. Kim, J. J. Song, J. H. Gim, B. J. Paul, J. G. Jo, W. G. Park, Y. P. Oh,
S. K. Nam, and J. K. Kim*
Department of Materials Science and Engineering, Chonnam National University
(email:[email protected])
Mono-dispersed and densely packed, LiFePO4 cathodes with high rate performance versus
lithium were synthesized using a two-step polyol process. The particle-size distribution and packing
density of LiFePO4 nanoparticles were fine-tuned via separation of the nucleation and particle
growth processes in the polyol medium by varying reaction time and temperature. Precisely, the
LiFePO4 samples were synthesized by heating the reaction mixtures at 200 C for various reaction
times (0, 1, 3 and 6 h) to facilitate nucleation and thereafter the solution temperature was raised
and maintained at 320 C to facilitate the crystal growth process. XRD studies confirmed the
formation of olivine phase in all the samples. The FE-SEM, FE-TEM and particle-size distribution
studies illustrate that the particle-size of olivine nanocrystals may be tuned to approximately 200
nm by controlling the aging time at 200 C or in other words separating the nucleation and crystal
growth process. The olivine cathodes synthesized by maintaining 3 6 h aging time demonstrate
improved discharge capacities and cycle performances in comparison to those of the remaining
samples. In particular, the 6 h olivine cathode registered average discharge capacities of 130, 87
and 64 mAh/g at 5 C, 10 C and 15.7 C current rates respectively.
*E-mail : [email protected]
Contact Phone : 062-530-0202
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-65
Nanostructure carbon coated LiFePO4 by a scalable polyol combustion
synthetic strategy
J. H. Gim1, V. Mathew1, S. H. Kim1, D. Y. Kim1, Y. E. Kim1, D. C. Ahn2,
W. B. Im1, Y. K. Paik3 and J. Kim1,*
1Department of Materials Science and Engineering, Chonnam National University,
Gwangju 500-757
2Beamline Research Division, Pohang Accelerator Laboratory, Pohang 790-8343Daegu Center, Korea Basic Science Institute, Daegu 702-701
(email:[email protected])
In the present study, carbon-coated lithium iron phosphate (LiFePO4/C) is prepared directly by
a polyol assisted pyro-synthesis performed under reaction times of a few seconds in open-air
conditions. The polyol process is generally represented by the reaction of metallic precursors in a
polyol solvent maintained near or at its boiling point. Here, the polyol solvent, tetraethylene glycol
(TTEG), acts as a low-cost fuel to facilitate combustion and the released exothermic energy
promotes the nucleation and growth processes of the olivine nanoparticles. In addition, phosphoric
acid (used as the phosphorous source) acts as a catalyst to accelerate polyol carbonization. The
structure analysis of the as-prepared LiFePO4/C using X-ray and neutron diffraction and 7Li NMR
studies suggested the efficacy of the rapid technique to produce highly crystalline phase-pure olivine
nanocrystals. The electron microscopy and particle-size distribution studies revealed that the average
particle diameters lie below 100 nm and confirmed the presence of a surface carbon layer of 2-3
nm thickness. The thermal and elemental studies indicated that the carbon content in the sample
was approximately 5 %. The prepared LiFePO4/C cathode delivered capacities of 162 mAh/g at 0.1
C-rate with impressive capacity retention for extended cycling. The polyol-assisted pyro-synthesis,
which evades the use of external energy sources, is not only a straightforward, simple and timely
approach but also offers opportunities for large-scale LiFePO4/C production.
*E-mail : [email protected]
Contact Phone : 062-530-0202
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-66
Impedance Spectroscopy on Multiferroic Bi0.5K0.5TiO3-BiFeO3
Su-Hyun Moon, Ji-Hoon Kim, Eui-Chol Shin, John Gerard Fisher and Jong-Sook Lee*
School of Materials Science and Engineering, Chonnam National University, Gwangju
500-757, Korea
For the electrical characterization of ferroelectric materials, dielectric constants and loss tangent
values are presented as a function of temperature at fixed frequencies. Strong frequency dispersion
observed in many complex perovskites could not be clearly explained and thus the Curie
temperature becomes poorly defined. A Voigt model for the grain boundary and electrode
polarization for the finite resistance high temperature behavior. Model analysis employs constant
phase elements with arbitrarily adjustable frequency dispersion instead of the ideal capacitor models
and resistors. The approach is problematic in characterization of the dielectric properties since the
capacitances are poorly defined. Often, a Maxwell model for the dielectric relaxation is also
employed for the same AC data with an inherent inconsistency. The AC behavior of much studied
BiFeO3-related multiferroic complex oxides shows these issues with a further complication of the
coupling between the electrical and magnetic properties. Electrical modeling where two dieletric
polarization effects and DC resistance are connected in parallel is found to competently describe the
AC behavior over the wide temperature ranges, where the dispersive response is described by a
Cole-Davidson dielectric function in parallel to the ideal capacitance element. Two capacitance
effects appear to correspond to the dielectric behavior of Bi0.5K0.5TiO3 and BiFeO3, respectively,
suggesting the application of the additivity and universality of the ion polarizabilities well-known
for the silicate minerals.
*E-mail : [email protected]
Contact Phone : 062-530-1701
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-67
Understanding electrochemical reaction of orthorhombic NCO using in-situ
X-ray Diffraction for sodium ion batteries
J. J. Song, J. H. Gim, S. J. Kim, J. G. Jo, S. H. Park, P. T. Duong, J. H. Yang, J.
Lee, and J. K. Kim,*
Department of Materials Science and Engineering, Chonnam National University
(email:[email protected])
In this work, almost pure NaxCoO2 (x = 0.71) sample has been prepared via a solid-state
route. The stoichiometric composition has been estimated by ICP-AES analysis and the Rietveld
refinement performed on the respective XRD pattern led to an orthorhombic structure in the Cmcm
space group with a = 2.83218(3)Å, b = 4.89983(4)Å, c = 10.92334(14)Å. The insertion/deinsertion
of sodium into the well-crystallized particles leads to capacities as high as 70.4 mAhg-1 with an
initial Coulombic efficiency of 90%, and excellent capacity retention of almost ~100% after the
90th cycle between a 2.0~3.5 V voltage window for a 0.08 C-rate. The insertion ratio (x) varied
between 0.592 and 0.673 during the deinsertion/insertion process within NaxCoO2. The voltage
profile shows numerous voltage steps being mainly associated to the slight ordering of the Na ions
within the layers. By coupling the electrochemical process with an in-situ X-ray diffraction
experiment, the c-axis and a-axis peak positions such as (002), (004) and (100) are shifted with the
accompanying deintercalation/intercalation of sodium, suggesting that the extracted sodium has been
reversibly occupied with a small variation in sodium composition ranges due to peculiar
Na+/vacancy ordering.
*E-mail : [email protected]
Contact Phone : 062-530-0202
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-68
In-depth Electrical characterization of Dye-Sensitized Solar Cells by Impedance
Spectroscopy Method
Dang-Thanh Nguyen1, Seok Jae Kim3, Eui-Chol Shin1, Soon-Hyung Kang2, Eun-Mi Han3
and Jong-Sook Lee1*
1School of Materials Science and Engineering, Chonnam National University, Gwangju
500-757, Korea2Department of Chemistry Education, Chonnam National University, Gwangju 500-757,
Korea3School of Applied Chemical Engineering, Chonnam National University, Gwangju
500-757, Korea
In spite of the worldwide extensive research efforts for the developments of dye-sensitized solar
cells in-depth electrical characterization using impedance spectroscopy appears to be limited to a
very few research groups. In this work, we characterized standard dye-sensitized solar cells (DSSCs)
constituted of a nanostructured TiO2 semiconductor on a transparent conducting oxide (TCO), a
photoactive dye material (N719 dye), and Pt counter electrode by impedance spectroscopy method
as well as IMVS/IMPS. In IMVS/IMPS the kinetic parameters including the recombination lifetime
and transport coefficients and diffusion length of the DSSCs are estimated using light-modulated
approaches by AC measurements at different light intensities at open-circuit/short-circuit condition,
respectively. The light sources are 530nm and 627nm. The impedance is measured at different
potential values of current-voltage curves including open-circuit/short-circuit condition in dark and
under illumination at different wavelength and intensity. The general impedance model reported by
Bisquert group has been successfully applied. The kinetic parameters from impedance analysis are
compared with those from IMVS/IMPS. The difference in the cell performance of many laboratory
prepared cells will be in-depth understood.
*E-mail : [email protected]
Contact Phone : 062-530-1701
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-69
Moving boundary diffusion mechanism in non-monotonic hydration/dehydration
AC relaxation in protonic conducting perovskites
Dong-Chun Cho, Gye-Rok Kim, Eui-Chol Shin and Jong-Sook Lee*
School of Materials Science and Engineering, Chonnam National University, Gwangju
500-757, Korea
Recently, the mechanism generally applied to all protonic ceramic conductors exhibiting
non-monotonic conductivity relaxations has been revealed. Similarly activated faster hydrogenation
and slower oxygenation process can be explained by the moving boundary diffusion mechanism
previously evidenced by in-situ optical spectroscopy where the hydrogenation kinetics is limited by
the hydration front. The conventional DC conductivity method provides only the integral
conductivity value of the sample with the non-trivial diffusion processes. The large number of
complex impedance data at different frequencies could provide more information on the situation
inside the materials or devices. Therefore AC method was employed for non-monotonic conductivity
relaxation phenomena in protonic ceramic conductors in perovskite structure. AC measurements were
performed over the frequency range from 10MHz to 10Hz using a disk sample of 5mol%
Yb-doped SrCeO3 (SCYb) and 15mol% Y-doped BaCeO3 (BCY) upon hydration/dehydration at
700°C, 650°C, and 600°C. The frequency sweep requires less than 1 min, which is sufficiently
short to monitor the relaxation proceeding over hours. High temperature spectra, however, are
strongly affected by the stray impedance at high frequencies. Modeling including the stray effects is
thus essential for the parametric analysis. Different AC characteristics of protonically conducting
perovskites will be compared for the model development.
*E-mail : [email protected]
Contact Phone : 062-530-1701
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-70
Polyol-mediated solvothermal synthesis and improved electrochemical
performance of novel K-doped Co3O4 as negative electrode for secondary
lithium-ion batteries
J. G. Jo, Z. Xiu, M. H. Alfaruqi, V. T. Trang, S. G. Lee, and J. K. Kim*
Department of Materials Science and Engineering, Chonnam National University, 300
Young-bong dong, Bukgu, Gwangju 500-757, Korea
(email:[email protected])
The exploration of 3d transition-metal oxides (MO, M = Fe, Co, Ni, Cu, etc.) as negative
electrodes for lithium ion batteries has received great attention recently. These oxides are attractive
alternatives to graphite and they can deliver high reversible capacities. Co3O4 is considered as a
promising alternative anode material for LIBs due to its high theoretical capacity (890mAhg-1). It
can store more than eight lithium ions per formula unit during charge/discharge. However, there are
some factors limit the performance of Co3O4 such as its poor electrical conductivity and large
volume expansion/contraction as well as severe particle aggregation associated with the Li+-insertion
and extraction process, which eventually lead to electrode pulverization and the loss of inter-particle
connectivity. This results in a large irreversible capacity loss and poor cycling stability. It is well
known that the particle size, morphology, and structure of electrode materials play important roles
in determining the electrochemical performance. Several methods have been developed the prepare
Co3O4 and overcome these problems, including the use of carbon based nano-composites and
increasing the specific surface area by preparing nanoparticles with various morphologies and
dimensions. However, to maintain and superior rate capability of the Co3O4 electrode material still
remain challenging issues. In the present work. a novel approach to improve the electrochemical
performance of the Co3O4 nanostructure by potassium ion (K+) doping is reported.
Nanostructure K+-doped Co3O4 was prepared via polyol-mediated solvothermal synthesis.
Electrochemical tests demonstrate that the K+-doped Co3O4 could exhibit high charge/discharge
capacity, long cyclability and high rate capability without noticeable capacity fading. This strategy
features a facile procedure with a novel dopant for realizing the large-scale production of Co3O4
nanoparticles with improved electrochemical performance.
*E-mail : [email protected]
Contact Phone : 062-530-0202
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-71
졸 -겔 방법 및 다공성 알루미나 멤브레인을 이용하여 제작된
Pb(Zr0.52Ti0.48)O3나노튜브 어레이의 압전 특성 연구
김병훈, 양선아, 강신욱, 부상돈*
전북대학교 물리학과, 전주 561-756
대표적인 강유전체 물질인 Pb(Zr,Ti)O3는 높은 압전 특성 (d33=190pC/N)을 가지고 있기 때
문에 널리 사용되고 있다. 최근 강유전체의 나노구조물은 에너지 하베스트, 압전 변환기, 액추
애이터 등과 같은 많은 응용분야에서 매우 유망하다. 특히 나노막대, 나노선, 나노튜브와 같은
1차원의 나노구조물이 주목을 받고 있는데, 이는 전도성 기판위에 균일하게 잘 정렬되어 분포
되어 있는 경우 큰 활동 표면적을 가져 고출력밀도에 활용하기 적절하기 때문이다. 1차원 나
노구조물 중에서도 나노튜브는 속이 빈 구조와 높은 종횡비에서의 안정성 때문에 나노막대나
나노선보다 높은 잠재력을 가진다. 따라서 전도성 기판 위에 균일하게 잘 정렬되어있는 나노
튜브 제작 연구와 압전 특성 연구가 필요하다. 본 연구에서는 졸-겔 방법과 다공성 알루미나
멤브레인을 주형틀로 이용하여 다결정 Pb(Zr0.52Ti0.48)O3(PZT)나노튜브 어레이를 제작하였으며,
그들의 압전 특성을 piezoresponse force microscopy (PFM)을 이용하여 관찰 하였다. PZT 나노
튜브는 Pt/Si 기판 위에 준비된 PAM 위에 PZT 졸-겔 용액을 도포한 후 스핀코팅과 500 oC에
서 700 oC의 다양한 온도에서의 열처리 과정을 거쳐 제작되었다. 그 후 주형틀을 선택적으로
식각함으로써 기판위에 수직적으로 서있는 PZT 나노튜브 어레이를 얻을 수 있었다. 제작된
나노튜브의 평균 직경, 높이, 벽두께는 각각 320 nm, 1000 nm, 그리고 60 nm로 관찰되었으며,
550 oC의 열처리 온도 이상에서 페로브스카이트 구조를 가진 나노튜브가 형성되는 것을 확인
하였다. PFM phase 이미지 분석을 통하여 본래 나노튜브가 가지는 수직방향의 도메인을 관찰
하였으며, 나노튜브의 분극 방향이 외부 전기장에 의해 스위칭 되는 것을 관찰 할 수 있었다.
또한, 열처리 온도에 따른 나노튜브의 압전 특성을 분석한 결과 650 oC에서 열처리한 나노튜
브가 가장 높은 압전 특성을 보이는 것을 관찰할 수 있었다.
*E-mail : [email protected]
Contact Phone : 010-7139-4264
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-72
CaBi4Ti4O15세라믹스의 전기적 특성에 감마선 조사가 미치는 영향
전도현, 최기쁨, 조삼연, 부상돈*
전북대학교 물리학과, 전주 561-756
강유전체 물질은 강유전 특성과 압전 특성으로 인해 압전 센서나 비휘발성 메모리 등 많
은 분야에서 널리 이용되고 있으며, 특히 PZT 같은 높은 강유전 특성과 압전 특성을 보이는
물질들이 많이 사용되고 있다. 그러나 최근 우주 항공 산업의 발달과 함께 우주 같은 극한 환
경에서 사용하기 위한 물질에 대한 연구가 활발히 진행됨에 따라, PZT 같은 강유전체 물질은
상전이 온도가 낮은 물질들은 고온에서 활용도가 제한되므로 극한환경에 적합하지 않기 때문
에 상전이 온도가 높은 강유전체 물질에 대한 연구가 필요하다. 강유전체 물질 중CaBi4Ti4O15
세라믹스는 높은 상전이 온도와 낮은 유전상수, 낮은 열화특성, 낮은 온도계수, 그리고 높은
품질계수를 가지기 때문에 우주나 원자력 발전소 같은 극한 환경에서 사용하기 위한 압전 소
자용 물질로 높은 가능성을 보이지만, 아직 방사선 조사에 의한 특성 변화에 대한 연구는 진
행되어 있지 않다. 감마선 조사에 의한 물질의 특성변화 연구는 주로 total ionization dose [1],
displacement damage [2], 그리고 single event effect [3] 세가지 모델을 적용하여 진행되고 있다.
따라서 본 연구에서는 감마선을 조사하여 총선량에 따른 CaBi4Ti4O15세라믹스의 특성 변화를
위의 세가지 모델로 분석하였다.
CaBi4Ti4O15세라믹스는 고상 반응법으로 제작하였으며, 이 시료에 감마선을 조사하여 유전
특성, 압전 특성, 그리고 강유전 특성의 변화를 측정하였다. 준비된 시료는 XRD 분석을 통해
CaBi4Ti4O15단일구조를 확인 하였으며, 100 kHz에서 유전상수 값이 151 그리고 유전손실 값이
0.001로 그리고 상전이 온도는 790 oC로 측정되었다. 이 시료에 0 1 MGy까지 다양한 총선
량으로 감마선을 조사하여 그에 따른 특성 변화를 관찰하였고, 그 결과를 통해서 CaBi4Ti4O15
세라믹스에 감마선 조사가 미치는 영향에 대해 위에서 제시한 3가지 모델 중 가장 적합한 모
델을 제시하고자 한다.
[1] D. Neamen, W. Shedd, and B. Buchanan, Nuclear Science, IEEE Transactions on 21, 211 (1974)
[2] M. Burton, J. Phys. Chem. 51, 611 (1947)
[3] Binder, D., E. C. Smith, and A. B. Holman. Nuclear Science, IEEE Transactions on 22 2675 (1975)
*E-mail : [email protected]
Contact Phone : 010-7139-4264
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-73
Carbon-nanotube-encapsuled Ferroelectrics Nanocrystals for Energy Harvesting
by Mechanical Movements
J. K. Han1, D. H. Jeon1, S. Y. Cho1, S. W. Kang1, S. A Yang1, K. Y. Choi2, E. J.
Ra3, J. S. Lim3, and S. D. Bu1*
1Department of Physics, Chonbuk National University, Jeonju 561-7562Department of Physics and Astronomy, Seoul National University, Seoul 151-747
3Thin Film Materials Research Group, Division of Advanced Materials, Korea Research
Institute of Chemical Technology, Daejeon 305-600
Nanogenerators that harvest energy from mechanical vibration are an attractive area of
nanotechnology fields. Recently, composite-type nanogenerator consisting of piezoelectric
nanostructures and multi-walled carbon nanotubes (MWCNTs) is one of the excellent candidates for
the future energy harvesting because of a great electrical and mechanical properties of MWCNTs.
Researches are focused on obtaining highest output power and understanding the role of the
MWCNTs in the composite-type nanogenerators. However, the role of the MWCNTs is not fully
understood because most composite-type nanogenerators are made by mixing MWCNTs and
piezoelectrics in the polymer matrix. The interconnected piezoelectrics on MWCNTs provides not
only key information to understand a systematic role of MWCNTs in nanogenerator property but
also effective transfers the stress occurred to the MWCNT.
We report a successful growth of Pb(Zrx,Ti1-x)O3 (PZT) nanoparticles (NPs) interconnected with
MWCNTs (PZT NPs-CNT) through injection method of sol-gel solution into a filter for squeezing
them and annealing for crystallizing them. High resolution transmission electron microscope analysis
of PZT NPs-CNT reveals that the PZT NPs have a diameter of 20 30 nm and are polycrystalline
with a tetragonal structure. In order to form the flexible thin film, the PZT NPs-CNT was
dispersed in polydimethylsiloxane as a matrix and spin-coated until 200 μm in thickness. By
periodic bending or tapping movements, the open-circuit voltage and short-circuit current of the
PZT NPs-CNT reaches about 3 V and 30 nA, respectively. In order to confirm that the signal
comes from the pieozoelectricity, we measured polarity property by a reverse connection in the
circuit and compared the output voltage with and without poling process. We will discuss the role
of the MWCNTs by measuring the output powers of PZT NPs-CNT.
*E-mail : [email protected]
Contact Phone : 063-270-4264
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-74
The use of (NH4)2WS4 precursor as hole extraction layer in organic
photovoltaic cells
Quyet Van Le, Thang Phan Nguyen, Soo Young Kim*
School of Chemical Engineering and Materials Science
Chung-Ang University 221, Heukseok-dong, Dongjak-gu, Seoul 156-756, Republic of
Korea
This study reports a facile method to fabricate the hole extraction layer (HEL) for organic
photovoltaic cells (OPVs) by thermally annealed (NH4)2WS4 precursor in air condition. The thermal
decomposition of (NH4)2WS4 was systematically study using thermal gravimetric analysis, ultra-violet
photoelectron spectroscopy (UPS), x-ray photoelectron spectroscopy, atomic force microscopy, and
transmittance spectra. The UPS data shows that the work function of HEL based (NH4)2WS4 (250 oC) is 5.05 eV, indicating the good alignment energy between ITO and the active layer based poly
(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester. Therefore, the use of HEL based
(NH4)2WS4 precursor improves the power conversion efficiency (PCE) of OPVs from 1.51 % (OPV
based bare ITO) to 3.14 %, which is comparable to that of device based poly
(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS) (PCE = 3.23%). In addition,
PEDOT:PSS was inserted between (NH4)2WS4 (250 oC) and active layer, the PCE increase up to
3.41 %, demonstrating that HEL based (NH4)2WS4 precursor is a potential candidate for hole
transfer layer in electronic device.
Acknowledgement
This research was supported by the Mid-Career Research Program (2014R1A2A1A11051098)
through the National Research Foundation of Korea (NRF), which is funded by the Ministry of
Education, Science, and Technology.
*E-mail : [email protected]
Contact Phone : 02-820-5875
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-75
Facile route for the synthesis of MoS2andWS2nanodots
Thang Phan Nguyen, Kyoung Soon Choi, and Soo Young Kim*
School of Chemical Engineering and Materials Science, Chung-Ang University 22,
Heukseok-dong, Dongjak-gu, Seoul 156-756, Republic of Korea
Liquid phase sonication method was adopted to fabricate single layer of molybdenum disulfide
(MoS2) and tungsten disulfide (WS2) by using dodecylbenzenesulfonate 0.1 wt% in de-ionize water
solution. MoS2 and WS2 nanosheets are easily broken by heating the ethylene glycol solvent,
which made MoS2 and WS2 nanosheets to nano dots without employing high pressure or other
complicated conditions. To characterize synthesized MoS2 and WS2, UV-vis absorption, Raman
spectra, x-ray photoemission spectra, and photoluminescence spectra are measured. Peaks of excited
states were shown in UV-absorption spectra in MoS2 nanosheet. Two MoS2 peaks shifted from 693
nm (1.79 eV) and 645 nm (1.92 eV) to 671 nm ( 1.85 eV) and 610 nm (2.03 eV) after heating
treatment, confirming the reduction of size. Exciton peaks of WS2 also changed from 640 nm (1.94
eV) to 624 nm (1.99 eV) when size was reduced to nano sheets. Especially, only one peak
appeared at 296 nm for MoS2 and 322 nm for WS2 after nano sheets were changed to nano dots.
Atomic force microscope image showed that the thickness of single layer MoS2 is 0.65 nm and
that of WS2 is 0.7 nm. Photoluminescence spectra showed that the highest intensity peaks of MoS2
and WS2 are located at 500 nm and 445 nm. These results indicate that MoS2 and WS2 nano
dots could be employed as enhancers or markers in optical devices, bio-image, bio-sensor, and so
on.
Acknowledgement
This research was supported by the Mid-Career Research Program (2014R1A2A1A11051098) through
the National Research Foundation of Korea (NRF), which is funded by the Ministry of Education,
Science, and Technology.
*E-mail : [email protected]
Contact Phone : 02-820-5875
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-76
Piezoelectric and Electrical Properties of Li-doped (Bi0.5Na0.5)TiO3-PVDF
Composite for Energy Harvesting
Joong-Hyeon Ahn and Jung-Hyuk Koh*
School of Electrical and Electronics Engineering, Chung-Ang University, Seoul, 156-756,
Korea
Recently, one of interesting candidates of lead free piezoelectric materials for energy harvesting
is Bismuth sodium titanate(abbreviated to BNT) because of the strong ferroelectric properties.
However, piezoelectric ceramic materials have commonly brittleness, poor fatigue resistance. Polymer
composites have been paid attention owing to their unusual physical properties. For these reasons,
ceramic-polymer composite has been considered to be an alternative for energy harvesting using
piezoelectric materials. To improve the piezoelectric and fatigue resistance properties of BNT
ceramics, BNT based solid solutions have been developed and extensively studied. On the contrary
to common polymers, Polyvinylidene fluoride(abbreviated to PVDF) have piezoelectric, dielectric and
good mechanical properties. The sintering temperature of BNT ceramics is very high
temperature(about 1180 °C) but melting point of PVDF is very low temperature(about 170 °C). To
overcome these problems, lithium as low sintering agent was added into BNT PVDF composite.
In this study, Li doped BNT PVDF composite for energy harvesting was manufactured with
various BNT PVDF ratios (PVDF= 0-20 wt.%). The crystalline properties of BNT PVDF were
investigated by X-ray diffraction (XRD) analysis. The microstructure were observed using field
emission scanning electron microscopy (FE-SEM). In addition, piezoelectric constant, dielectric
constant, mechanical quality factor, electromechanical coupling factor will be discussed.
*E-mail : [email protected]
Contact Phone : 02-820-5311
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-77
Enhanced Piezoelectric and Dielectric Properties of Na0.5K0.5NbO3-CaCu3Ti4O12
Lead-Free Composite
Jae-Hoon Ji and Jung-Hyuk Koh*
School of Electrical and Electronics Engineering, Chung-Ang University, Seoul, 156-756,
Korea
Lead zirconate titanate-based (PZT-based) ceramics have been intensively employed functional
electronic devices applications such as sensors, actuators and transducers due to their excellent
piezoelectric properties. However, the use of lead-based ceramics can contaminate the environment
and deteriorate human health. Owing to these concerns, there have been many attempts to replace
lead-based piezoelectric ceramics with lead-free ceramics. (Na0.5K0.5)NbO3 (NKN) has been
considered candidate for lead-free ceramics due to outstanding piezoelectric properties and Curie
temperature of about 420 °C. However, dense NKN ceramics are difficult to be obtained due to the
volatilization of K-ion and Na-ion at high sintering temperature. To complement this drawback of
NKN ceramics, other materials such as BaTiO3, CaTiO3 and CuO have been added into NKN
ceramics to form solid solution. Therefore, NKN based ceramics can increase densification and
present relatively superior piezoelectric properties. Also, CaCu3Ti4O12 (CCTO) with perovskite-like
compound has high dielectric constant as 12,000 at 1 kHz at room temperature. Thus, NKN-CCTO
can improve densification and dielectric properties. In this study, dielectric and piezoelectric
properties of (1-x)(Na0.5K0.5)NbO3 xCaCu3Ti4O12 (x=0, 0.05, 0.10, 0.15, 0.20) ceramics will be
investigated by conventional mixed oxide method and sintering process. The crystalline structure of
NKN CCTO were measured by X-ray diffraction (XRD) analysis. The microstructure were
examined by scanning electron microscopy (SEM). In addition, piezoelectric coefficient, d33, electro
mechanical coupling factor, kp, mechanical quality factor, Qm, dielectric constant, εr, will be
discussed.
*E-mail : [email protected]
Contact Phone : 02-820-5311
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-78
Temperature Dependent Ferroelectric and Field-Induced Strain Response of
Nb-doped BNBT-SZ Lead-free Piezoelectric Ceramics
Adnan Maqbool,1 Ali Hussain,1 Jamil Ur Rahman,1 Rizwan Ahmed Malik,1 Tae Kwon
Song,1 Won-Jeong Kim,2 and Myong-Ho Kim1*,
1School of Advanced Materials Engineering, Changwon National University, Gyeongnam
641-773, Republic of Korea2Department of Physics, Changwon National University, Gyeongnam 641-773, Republic of
Korea
Lead-free piezoelectric ceramics, (Bi0.5Na0.5)0.935Ba0.065Ti(1 x)NbxO3 0.01SrZO3(BNBTNb100x
SZ, with x = 0 1) were synthesized and its crystal structure, dielectric properties, electric
field-induced strain (EFIS), and polarization response was systematically investigated. X-ray
diffraction analysis revealed that all compositions had a pure perovskite structure with tetragonal
symmetry. The depolarization temperature (Td) shifted toward lower temperature sand the dielectric
curves became more diffuse within creased Nb-doping, producing a significant disruption of the
long-range ferroelectric order. A giant EFIS of 0.33% was achieved at an optimized composition of
Nb1.0 (BNBTNb1.0 SZ), corresponding to a normalized strain (Smax/Emax) of 825 pm/V at a low
applied field of 4 kV/mm. Furthermore, the temperature dependence of polarization and
field-induced strain showed a stable response up to 100°C. These results suggest that BNBTNb SZ
ceramics are promising candidate materials for lead-free actuator applications.
Keywords: lead-free, dielectric, relaxor behavior, incipient piezoelectrics, Electric field-induced strain
*E-mail : [email protected]
Contact Phone : 052-259-1930
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-79
Compositional-induced structural and non-ergodic to ergodic relaxor transition
in lead-free Ta-doped Bi0.5(Na0.84K0.16)0.5TiO3 SrTiO3 ceramics
Rizwan Ahmed Malik1, Ali Hussain1, Arif Zaman2, Tae Kwon Song1,
Won-Jeong Kim3 and Myong-Ho Kim1,*
1School of Advanced Materials Engineering, Changwon National University, Gyeongnam
641-773, Republic of Korea2Department of Physics, Abdul Wali Khan University, Mardan, KPK, Pakistan
3Department of Physics, Changwon National University, Gyeongnam 641-773, Republic of
Korea
The effect of Ta substitution on the crystal structure, electromechanical, dielectric, and
piezoelectric properties of BNKTT ST ([0.96Bi0.5(Na0.84K0.16)0.5Ti1-xTaxO3] 0.04SrTiO3 where x =
0.00 0.030) ceramics has been investigated. X-ray diffraction patterns revealed that Ta doping
resulted in a transition from coexistence of rhombohedral and tetragonal phases to a pseudocubic
phase. Both the dielectric constant and depolarization temperature decreased with an increase in
Ta-content. The piezoelectric and ferroelectric responses of the BNKT ST ceramics was
significantly decreased by the addition of Ta content. However, the destabilization of the
piezoelectric and ferroelectric properties is accompanied by significant enhancements in the bipolar
and unipolar strains. A large electric field-induced strain (S = 0.38%) and a corresponding
normalized strain (Smax/Emax = 633 pm/V) were observed under 6 kV/mm when 2% Ta was
substituted on Ti sites. This significant strain enhancement at x = 0.020 composition may be
attributed to both the compositional-induced structural phase transition and a non-structural non
ergodic to ergodic relaxor phase transition.
Keywords: Lead-free, piezoelectricity, Ferroelectricity, Phase transitions, Electrical properties
*E-mail : [email protected]
Contact Phone : 055-213-3719
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-80
새로운 비납계 BiFeO3-BaTiO3 압전 재료의 물성 평가
D. J. Kim1, M. H. Lee1, J. S. Park1, M.-H. Kim1,
S. S. Kim2, D. Do3, H. Y. Lee4, and T. K. Song1*
1School of Materials Science and Engineering, Changwon National University, Changwon
641-7732Department of Physics, Changwon National University, Changwon 641-773
3Department of Advanced Mat. Eng., Keimyung Univ., Daegu 704-701
4Ceracomp Co., Ltd. Cheonan, 330-816
Bi를 기반하는 물질 BiMeO3 (Me = Fe, Cr, Co)들은 높은 상전이 온도를 가진다고 알려
져 있으며, 특히 BiFeO3 의 경우, 상전이 온도가 830 oC 정도로 높지만 높은 누설 전류로 인해
낮은 강유전성을 가진다. BaTiO3 의 경우, 대표적인 비납계 압전 및 강유전성 재료이나 낮은
상전이 온도로 인해 응용에 제한이 된다. 최근에 BiFeO3 BaTiO3 (BF-BT) 고용체 형성하여 압
전 및 강유전 특성을 보고하면서, 새로운 비납계 압전 재료로서의 가능성을 제시하였다.
현재 비납계 압전 재료의 개발에서 대체로 고상반응법을 이용하여 세라믹 제조 방법이 활
용되고 있으나 실제 응용을 위해서는 후막공정의 개발이 필요하다. 이 후막공정에서 BF-BT계
는 두 가지 정도의 장점을 갖는다. 우선 낮은 소결온도를 갖기 때문에 싼 가격의 내부 전극을
활용할 수 있는 가능성이 높다. 더불어 소결공정이 빠르고 에너지 소비가 적을 수 있다.
테이프 캐스팅 방법을 이용한 BF-BT 세라믹스를 소결 시간에 따른 압전 및 강유전 특성
을 평가하였다. XRD에서는 불순물 상은 형성되지 않았으며, 소결 시간이 증가함에 따라, 낟알
의 크기도 점차 증가함을 알 수 있었다. 조성 분석 결과, 조성 변화가 거의 없는 것을 알 수
있으며, 최적의 소결 시간에서 높은 압전(d33= 189 pC/N) 및 강유전 특성(Pr= 20 μC/cm2 , Ec =
22 kV/cm) 을 관찰하였다. 더불어 BF-BT 박막 제조 및 물성 평가에 대한 연구 결과를 소개한
다.
*E-mail : [email protected]
Contact Phone : 055-213-3713
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-81
Structural, electrical and multiferroic properties of chemical solution deposited
Aurivillius Bi7Fe3Ti3-xNbxO21 thin films
C. M. Raghavan, J. W. Kim, J. Y. Choi, M. J. Lee and S. S. Kim*
Department of Physics, Changwon National University, Changwon, Gyeongnam 641-773
The effects of Nb5+-ion doping on the structural, electrical and multiferroic properties of six
layered Aurivillius Bi7Fe3Ti3O21 thin film are investigated. The Bi7Fe3Ti3-xNbxO21 (x=0 and 0.06)
thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution
deposition method. Significant improvements were observed in the electrical, dielectric and
multiferroic properties when the Nb5+-ion incorporated into the Ti-site of the Bi7Fe3Ti3O21 thin film.
From electrical study, the Bi7Fe3Ti2.94Nb0.06O21 thin film exhibited low leakage current density of
5.11×10-6A/cm2 at 100 kV/cm, it was about one order of magnitude lower than that of the
Bi7Fe3Ti3O21 thin film. From the ferroelectric study, the Bi7Fe3Ti2.94Nb0.06O21 thin film showed large
remnant polarization (2Pr) of 20.52 μC/cm2 at an applied electric field of 630 kV/cm, while the
measured 2Pr value for the Bi7Fe3Ti3O21 thin film was 3.5 μC/cm2 at an applied electric field of
318 kV/cm. Furthermore, well saturated magnetic hysteresis loop with enhanced magnetization was
observed for the Bi7Fe3Ti2.94Nb0.06O21 thin film.
*E-mail : [email protected]
Contact Phone : 055-213-3421
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-82
Study on the new type of piezoelectric actuator utilizing smooth impact drive
mechanism
M. H. Park1, H. H. Jeong2, S. S. Jeong3 and T. G. Park3*
1Defense Agency for Technology and Quality, Changwon 642-180,
2SAMJEON CO., LTD, Joil-Ri, Samdong-Myeon, Ulju-Gun, Ulsan 1313-3, 3Department of Electrical engineering, Changwon National University, Changwon 641-773
In this paper, the linear piezoelectric actuator utilizing smooth impact drive mechanism(SIDM)
was proposed. It is easy to fabricate actuator because of the simple structure of two bi-morph type
cantilevers without any rotators or sliders. The piezoelectric ceramics, called as legs, were composed
of two rectangular ceramics which were attached on the surfaces of the elastic bodies. FEA
simulation(Ansys) was used to optimize the actuator in order to increase its speed and force. When
rectangular voltages which have basically different ratio of positive and negative signals at
resonance frequency were applied, the piezoelectric actuator was moved by a stick-slip driving
mechanism. The actuator was driven by two successive motions of actuator legs, slow forward
movement and rapid backward movement. The output characteristics of the prototype actuator based
on the analysis data was measured.
*E-mail : [email protected]
Contact Phone : 055-283-8376
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-83
Ferroelectric properties of (1-x)BiFeO3-xBaTiO3 solid-solution thin films
J. S. Park1, M. H. Lee1, S. W. Kim2, D. J. Kim1,
S. J. Han2, S. Kumar3, M-H. Kim1, W-J. Kim2, and T. K. Song1*
1School of Materials Science and Eng., Changwon Nat’l Univ., Gyeongnam 641-773,
Korea2Department of Physics, Changwon Nat’l Univ., Gyeongnam 641-773, Korea
3Institute of Basic Sciences, Changwon Nat’l Univ., Gyeongnam 641-773, Korea
Thin films of lead-free ferroelectric material (1-x)BiFeO3-xBaTiO3 (BF-BTx) (x=0.3, 0.33, and
0.4) were deposited on a Pt(111)/Ti/SiO2/Si(100) substrates by pulsed laser deposition. The films are
deposited at various deposition temperature (550oC-580oC) by maintaining the PLD chamber at an
oxygen partial pressure of 30 mTorr. The BF-BT films were exhibited single-phase perovskite
structure by X-ray diffraction analysis. Deposited at 560oC the BF-BT films. electrical proreties
were shown the good ferroelectric, and low leakage current properties. The BF-BT33 flim was
exhibited remnant polarization 2Pr of about 32 µC/cm2 and coercive field 2Ec of 400
kV/cm. The leakage current at high applied fields was also effectively reduced and leading to
improved ferroelectric properties.
*E-mail : [email protected]
Contact Phone : 055-213-3890
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-84
Na0.5Bi0.5TiO3-BaZrO3 textured ceramics prepared by reactive templated grain
growth method
Ali Hussaina, Jamil Ur Rahmana, Adnan Maqboola, Rizwan Ahmed Malika,
Tae-Kwon Songa, Won-Jeong Kimb, and Myong-Ho Kima*
aSchool of Advanced Materials Engineering, Changwon National University, Gyeongnam
641-773, Republic of Korea bDepartment of Physics, Changwon National University, Gyeongnam 641-773, Republic of
Korea
In this work 0.94Na0.5Bi0.5TiO3-0.06BaZrO3 (NBT-BZ) ceramics were prepared by reactive
templated grain growth(RTGG) method using 15wt.% NBT template. The as synthesized NBT-BZ
textured ceramics were sintered at 1150 oC for different soaking time (2-15h) and their crystal
structure, microstructure, dielectric, ferroelectric and field-induced strain properties were investigated
and compared. Results show that al ltextured NBT-BZ ceramics have(h00) preferred orientation,
which increase with increase in the sintering soaking time. No significant change in the
depolarization temperature was observed in NBT-BZ textured ceramics with change in the sintered
time. However, the field induced strain response increased by 20% when the sintering time was
increase from 2h to 15h.
Keywords: NBT-BZ ceramics; textured ceramics; grain growth
*E-mail : [email protected]
Contact Phone : +82-55-213-3711, Fax: +82-55-262-6486
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-85
New high Curie temperature lead-free piezoceramics
in BiFeO3-BaTiO3 solid solution
이명환1, 김다정1, 박진수1, 김명호1, 송태권1†, 김상욱2, 김원정2, 김상수2, 장기완2
도달현3 , 정일경4
1창원대학교 신소재융합공학과, 창원 641-7732창원대학교 물리학과, 창원 641-773
3계명대학교 재료공학과, 대구 704-7014부산대학교 유전체물성연구소, 부산 609-735
Recently, (1-x)BiFeO3-xBaTiO3 (BF-BT) lead-free piezoelectric systems have potential to be
applied at a high operation temperature due to their high Tc. BF (rhombohedral phase) and BT
(tetragonal phase) solid solutions were observed in the complete compositional range with
rhombohedral (x = 0.00-0.33), pseudo-cubic (x = 0.33-0.92), and tetragonal (x = 0.92-1.00)
perovskite crystal structures.
In this study, (1-x)BiFeO3-xBaTiO3 (x = 0.20 to 0.5) bulk ceramic system was prepared via a
typical solid-state reaction process. The crystal phase, phase transition, microstructure, dielectric,
ferroelectric, and piezoelectric properties as functions of composition were investigated. Detailed
structural and electrical properties of BF BT ceramic will be presented concern with piezoelectric
application.
*E-mail : [email protected]
Contact Phone : 055-213-3713
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-86
Study on the output characteristics of the lambda type ultrasonic motor
depending on the polarization direction of the piezoelectric ceramic
S. K. Cheon1, S. S. Jeong1, Y. W. Ha1, B. H. Lee1, H. I. Jun2, T. G. Park1*
1Department of Electrical Engineering, Changwon National University, Changwon
641-7732Mattron corp, Changwon 630-724
In this paper, the ultrasonic motor which can replace existing ultrasonic motors for driving
camera zoom lens was proposed and experimented. The piezoelectric ceramics was composed of
two rectangular ceramics which was attached on upper surfaces of the elastic bodies as in figure.
The both polarization directions were directed to the outward directions. When two AC voltages
which have basically 90 degree phase difference were applied to the two ceramics, elliptical
displacements of the stator tips were obtained. FEA simulation(ATILA) was used to analyze
elliptical displacement characteristics of the friction tips depending on the polarization direction and
the phase change of applied voltage. The output characteristics of the prototype motor based on the
analysis data was measured.
Stator structure of the proposed ultrasonic motor
*E-mail : [email protected]
Contact Phone : 055-283-8376
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-87
Structure and electrical properties of rare-earth substituted K0.5Bi4.5Ti4O15 thin
films prepared by chemical solution deposition
J. Y. Choi, J. W. Kim, C. M. Raghavan, M. J. Lee and S. S. Kim*
Department of Physics, Changwon National University, Changwon, Gyeongnam 641-773
Ferroelectric thin films have been investigated for decades as nonvolatile ferroelectric random
access memories due to its potentially excellent properties of lower power requirements, faster
access speed and nonvolatility. Recently bismuth layer-structured ferroelectric (BLSF) thin films
have caused extensive attention as promising materials for the nonvolatile ferroelectric random
access memories due to their fatigue-free performance with Pt electrodes. K0.5Bi4.5Ti4O15 (KBTi) is
one of the important BLSFs. However, there were a few reports on the undoped and doped KBTi
thin film form. In this study, effects of Dy3+ and Gd3+-ion doping on the structural, electrical and
ferroelectric properties of the KBTi thin film were investigated. Pure KBTi and rare-earth(Dy3+ and
Gd3+)-doped KBTi thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a
chemical solution deposition method. The electrical properties of the thin films were investigated by
P-E hysteresis loops and leakage current conduction behavior measurements.
*E-mail : [email protected]
Contact Phone : 055-213-3421
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-88
Optical ad electrical properties of band-gap controlled
Ge doped ZnO1-xSx thin films
S. J. Han1, S. W. Kim1, M. H. Lee2, J. S. Park2, D. J. Kim2, D. Do3, M. H. Kim2,
T. K. Song2, and W. J. Kim1*
1Department of Physics, Changwon National University, Gyeongnam, 641-773, Korea.2School of Nano & Advanced Materials Engineering, Changwon National University,
Gyeongnam, 641-773, Korea.3Department of Advanced Material Engineering, Keimyung University, Daegu 704-701,
Republic of Korea.
Even though ZnO and ZnS, as II-VI semiconductors, share similarities in chemically and
structurally, both binary compounds do not form a solid solution in the entire compositional range
of S and O due to solubility limits of S in ZnO and O in ZnS in equilibrium states. In order to
fabricate the ZnO1-xSx thin films with 0<x<1, films were intentionally deposited in non-equilibrium
state by a pulsed laser deposition method while controlling oxygen pressures. The formation of the
intermediate structures between ZnO and ZnS were confirmed by an X-ray diffraction study. The
lattice constant changes continuously from ZnO to ZnS as increased S contents. Optical properties,
including energy band gap, and electrical properties were investigated. However, resistivity of
ZnO1-xSx thin films were too large to measure by Hall measurement method. Ge has been doped in
ZnO1-xSx thin film to increase electrical conductivity to study electrical properties of these films.
Details of structural, chemical, optical and electrical properties of Ge doped ZnO1-xSx thin films will
be discussed in the presentation.
*E-mail : [email protected]
Contact Phone : 055-213-3429
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-89
Metal-insulator transition in NdNiO3 by hydrogen doping
C. D Oh1*, S. Y. Heo2, H. M. Jang1,2 and J. W Son1
1Department of Materials Science and Engineering, Pohang University of Science and
Technology, Pohang 790-7842Division of Advanced Materials Science, Pohang University of Science and Technology,
Pohang 790-784
The rare-earth nickelate is perovskite oxide which is sensitive to the orbital occupancy of
electrons. The corner sharing NiO6 octahedra experience charge disproportionation in order to
stabilize the t2g6eg
1 electrons leading Ni4+t2g6eg
0 and Ni2+t2g6eg
2 configuration. Recently, hydrogen is
reversibly intercalated in SmNiO3 leading band gap modulation and giant resistance switching. The
electron configuration of hydrogen doped SmNiO3 is modified from Ni3+t2g6eg
1 to Ni2+t2g6eg
2 and it
suppresses charge disproportionation of NiO6 octahedra. It opens up new directions to explore
emerging electronic devices with nickelate systems.
Here we report a giant resistance change in NdNiO3 epitaxial thin films by hydrogen doping.
We prepared 25 nm-thick NdNiO3 thin film by pulsed laser deposition (PLD). Pt top electrode is
utilized as hydrogen dissociating catalyst. Clear metal-to-insulator transition was observed by color
change in hydrogen-treated NdNiO3 thin films. Electrical characteristic shows the giant change of
resistance. X-ray diffraction (XRD) and atomic force microscopy (AFM) data indicate that the
perovskite structure is maintained during hydrogenation accompanying unit cell expansion. We
demonstrated the resistance change is related to doping concentration of hydrogen and lattice strain.
*E-mail : [email protected]
Contact Phone : 052-279-2822
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-90
Hydrogen-bonding effects in organohalide-perovskite-based solar cells:
first-principles study
June Ho Lee1* and Hyun Myung Jang1,2
1Department of Materials Science and Engineering, Pohang University of Science and
Technology (POSTECH), Pohang 790-784, Republic of Korea2Division of Advanced Materials Science, Pohang University of Science and Technology
(POSTECH), Pohang 790-784, Republic of Korea
During the past two years, there have been rapid advances in solar-energy harvesting research
based on organic-inorganic hybrid perovskite absorbers (e.g., CH3NH3PbI3). The efficiency of this
type of solar cells is, in general, substantially higher than conventional dye-sensitized solar cells
(DSSC). However, these hybrid-perovskite-based solar cells are not fully optimized owing to the
lack of our in-depth understanding. In particular, the role of the organic-cation moiety (CH3NH3)+ is
not known because of their disordered nature of the (configurational) orientation in a perovskite unit
cell.
In order to identify the functional role of the organic-cation moiety in CH3NH3PbI3, we have
carried out first-principles density-functional theory (DFT) calculations focused on the possible
hydrogen-bonding interaction between the iodide (I) anion and the hydrogen (H) ions coordinated to
the nitrogen atom. In the present study, we have systematically investigated the structural change in
response to the variation in the orientation of organic functional groups in a given perovskite unit
cell. To simplify the combination of many possible orientations, we classify each case into
“ferroelectric (FE)” and “antiferroelectric (AFE)" configurations along x, y and z directions.
According to our detailed DFT calculations, the hydrogen bonding between I and H ions plays a
major role in controlling the degree of the tilting as well as the distortion of the PbI6 octahedron
unit in a perovskite unit cell.
*E-mail : [email protected]
Contact Phone : 054-279-2819
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-91
Modulated Spin Structure responsible for the Magnetic-Field-Induced
Polarization Switching in Multiferroic TbMn2O5
Jung-Hoon Lee1, Seungwoo Song1 and Hyun Myung Jang1,2*
1Division of Advanced Materials Science(AMS) and Department of Materials Science and
Engineering, Pohang University of Science and Technology(POSTECH), Pohang 790-7842Department of Physics, Pohang University of Science and Technology(POSTECH),
Pohang 790-784
Orthorhombic TbMn2O5 (o-TMO) is a well-known multiferroic manganite with its remarkable
property of the polarization switching at 3 K under a bias magnetic (H) field along the a-axis of
Pb21m. To theoretically account for this outstanding observation, we have proposed a modulated
spin structure under the saturated bias H-field by considering the relative strength of the three
relevant exchange parameters in o-TMO. The proposed modulated structure based on
density-functional theory (DFT) calculations is described in terms of the spin-angle between the
neighbouring Mn4+-Mn3+ spin moments on the a-b plane. We have shown that the computed DFT
polarization plotted as a function of satisfactorily accounts for the observed H-field-induced
polarization switching. We have further theoretically shown that the square of the critical
field-strength (Hc) needed for the polarization switching is inversely proportional to the degree of
the extrinsic magnetoelectric coupling. The computed partial charge density demonstrates that the
H-field-induced polarization switching also accompanies with the switching in the sign of the excess
valence-electron density.
*E-mail : [email protected]
Contact Phone : 054-279-2819
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-92
Rapid Thermal Heating Effects on the Zn0.85Mg0.15O:Ga Thin Films
Byeong-Eog Jun1*, Sunwoo Kim2, Sangwoo Kim2, Seongmin Lee2 , Jimin Koo2, and
Jong Rim Lee1
1Department of Physics and Earth Science, Korea Science Academy of KAIST, Busan
614-1002Korea Science Academy of KAIST, Busan 614-100
Gallium doped Zn0.85Mg0.15O (ZMO:Ga) thin films were studied for the fabrications of the
transparent homo double layers of the conductive and the insulator thin films. The 3 at.% gallium
doped ZMO:Ga target ceramics were prepared by using the conventional solid state reaction
methods. Then thin film of ZMO:Ga was coated on the sapphire (0001) substrates by using the
RF-magnetron sputtering methods at room temperatures. The as-coated ZMO:Ga thin films were
post annealed in the temperature range from 500°C to 1000°C at air atmosphere. The structural
and optical properties of ZMO:Ga thin films were analyzed by using the X-ray diffraction analysis,
the scanning probe microscopy and the UV-Vis range optical transmittances. The electrical
properties of the post-annealed ZMO:Ga thin films were investigated by using the Hall Effect
measurements and the 4-wire surface conductivities. As the annealing temperature is increased in
the temperature range from 500°C to 900°C, the X-ray scattering intensity of the (002) peak was
increased but the surface conductivity was decreased. The structural characteristic were considering
the homo double layers of the post annealed ZMO:Ga thin films as the insulating ZMO layer over
the conductive ZMO:Ga layer on the substrate.
*E-mail : [email protected]
Contact Phone : 051-606-2232
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-93
Preparations of the Ba1-xEuxTiO3 Ceramics in the Nitrogen Gas Ambient
Byeong-Eog Jun1*, Minki Kim2, Seung-Min Oh2 and Jong Rim Lee1
1Department of Physics and Earth Science, Korea Science Academy of KAIST, Busan
614-1002Korea Science Academy of KAIST, Busan 614-100
The barium europium titanate Ba1-xEuxTiO3 (BRT, x = 0 ~ 1.0) ceramics were prepared in the
nitrogen gas atmospheres for the perovskite structure. It is considered that the dielectric relaxations
is due to the magneto-polarization relaxation in the low temperatures. The perovskite BET (x =
0.30) ceramics showed the ferroelectric behaviors and the Maxwell-Wagner type dielectric
relaxations in the low frequency range from 10-2 Hz to 105 Hz. We are trying to confirm the
magneto-dielectric relaxation mechanism with varying temperature below room temperature in the
nitrogen gas ambient. It is expected that there occurs the valence electron hopping between the
partially filled d-orbitals and the p-orbitals in the Ba1-xEuxTiO3 (BET) ceramics. While the charge
frustrations of Eu atoms (Eu2+ Eu3+) results in the structural changes from the perovskite to the
pyrochlore structures. In this work, we tried to review the preparation of BET (x = 0 ~ 1.0)
ceramics by using the solid state synthesis method in the nitron gas ambient during the sinter
processes. The dielectric characterizations were performed in the low frequency range at the
nitrogen gas ambient.
*E-mail : [email protected]
Contact Phone : 051-606-2232
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-94
Optical Characterization of Semiconductor ZnxCu1-xO Nanoparticles Prepared by
Hydrothermal method
J. P. Kim1, *, S. H. Jung2, J. H. Kim1, M. G. Ha1, J. S. Bae1,
T. E. Hong1, E. D. Jeong1, K. S. Hong1, J. S. Jin1
1Korea Basic Science Institute Busan Center, Busan2Korea Basic Science Institute Gwangju Center, Gwangju
Compounds based on copper and oxygen were extensively studied immediately after the
discovery of high temperature superconductors. CuO has a monoclinic structure with C2/c space
group and Cu2O has cubic structure with Pn3m space group. Many authors have reported the
changes associated with doping of transition metal ions into CuO lattice, which have been observed
experimentally in Mn, Ni-doped CuO, Fe and Ni co-doped, Ti, Cd and Zn. Copper oxide is
considered as well-organized catalytic agent, solar technology and also a good gas sensing material.
In this study, Semiconductor ZnxCu1-xO were prepared by hydrothermal reaction method. The
phase formation processes and micorstructures were examined by high resolution X-ray diffraction
(XRD), transmission electron microscope (TEM). The chemical bonding states of nanoparticles is
measured by X-ray photoelectron spectroscopy (XPS).
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-95
Direct Adhesion of Polyphenylenesulfide Resin and Polymeric Film on Copper
by Surface Modification
Eun Hyuk Chung1, F. Nawaz Khan1,2, Tae Eun Hong1, Jong Pil Kim1, Jong-Seong Bae1,
and Euh Duck Jeong1*
1Division of High-Technology Materials Research, Korea Basic Science Institute, Busan
618-2302Organic Chemistry Division , School of Advanced Sciences, VIT University, Vellore,
Tamil Nadu, 632 014, India
Metal/polymer assemblies are employed in areas as diverse as decorative electrodes, corrosion
protection, microelectronics, molecular adhesion promoters, and facilitators of the release of metal
molds. Various surface modifications have been applied to improve adhesion properties of bivalent
metal such as copper and aluminum for electrodes terminal application and sealing for Li ion
batteries. In this study, we evaluated the effect of different solution condition and peel strength for
the adhesion of polymeric film on copper. Characterization of the copper surface was explored by
SEM, XPS and SIMS. SEM results reveal that the meaningful roughness was formed on the copper
surface in different solutions by chemical oxidation. SIMS results represent that the peel strength
was found to depend on film thickness and the composition of adhesion layer. As a result,
Metal/polymer assemblies developed in this study have superior adhesion property. Therefore, these
assemblies might be a viable candidate as a sealing technique for Li ion batteries, and will be
beneficial in reducing the process cost and increasing the safety of Li ion batteries.
*E-mail : [email protected]
Contact Phone : 051-974-6100
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-96
Glass formation conditions and photophysical properties of the
samarium-containing binary and ternary tellurium glass ceramics
강보배1, 하명규1, 김현규1, 양호순2, 홍경수1
1 한국기초과학지원연구원 부산센터
2 부산대학교 물리학과
Although tellurium (Te)-based glasses are very important materials in the field of glass science
and technology, tellurium oxide (TeO2) is a conditional glass former that cannot form glass by
itself when quenched from the liquid or vapor state. We establish the glass formation conditions for
the binary and the ternary tellurium-based glass systems and examine the structural and the optical
characteristics of this formation. Sm3+ is used to study the spectroscopic properties of materials.
We prepare the binary and the ternary tellurium-based glasses and investigate their characteristics.
We report the glass-formation conditions, the crystallinity, and the optical characteristics of the
binary TeO2-Sm2O3 and the ternary K2O-Sm2O3-TeO2 glasses before and after heat treatment. We
prepare several tellurium-based glasses by using the conventional melt-quenching method and
establish appropriate glass-formation compositions in both glasses. We anneal glasses for 2 h at
temperatures from 360 oC to 440 oC with a 10 oC interval, respectively, and observe the
crystallinity after annealing by using an X-ray diffractometer and a scanning electron microscope.
We show that glass ceramics after heat treatment forms in single phase crystals in both glasses,
and become phosphors under near ultra-violet excitation by measuring the optical properties such as
absorption, excitation, and emission spectra.
*E-mail : [email protected]
Contact Phone : 051-974-6106
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-97
BaTiO3 나노 입자의 소성 시 첨가제에 따른 미세구조 및 유전특성
The microstructure and the dielectric properties with additives in the sintering
of BaTiO3 nano particle
Jae Won Kang1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Dae Yong Jeong2
1)Korea Institute of Ceramic Engineering and Technology 233-5, Gasan-Dong,
Guemcheon-Gu Seoul, 153-801, Korea 2)School of Materials Science and Engineering, Inha University, Incheon, 402-751, Korea
BaTiO3는 MLCC에 사용되는 대표적인 물질이며 최근 전자기기의 소형화와 초고용량화
경향에 따라 MLCC의 유전체 층 또한 박층화와 다층화되고 있다. 이에 따라 BaTiO3의 초미립
화는 MLCC의 핵심적인 기술이며 초미립의 BaTiO3를 사용함에 따라 전기적 신뢰성이 향상되
므로 유전체 층의 형성 두께의 한계가 감소할 수 있다. 그러나 나노 BaTiO3를 사용할 경우 이
들 particle의 균일한 분산이 요구되며 전기적 특성의 제어와 grain size의 제어를 위하여 다양
한 첨가제들이 첨가되어야 한다. 이들 첨가제는 소량으로 첨가되고 또한 균일한 분산이 필수
적이므로 액상 첨가제를 이용한 조성의 개발이 필요하다. 특히, 나노 크기의 원료 powder를
적용할 경우 소결시 생성되는 액상이 변화하므로 첨가제 조성의 큰 변화가 예상되지만 이러
한 원료 입자 크기에 따른 첨가제 조성의 영향에 대한 구체적인 연구는 미흡한 실정이다. 따
라서 본 연구에서는 80 BaTiO3 powder에 Dy, Mg, Mn, Cr, Si, Ba등의 첨가제들을 액상 코팅
방법으로 첨가하여 Core-shell 구조를 형성하고 첨가제 변화에 따른 나노 BaTiO3 소결체의 미
세구조 및 유전특성을 평가하였다. 이 결과를 바탕으로 80nm BaTiO3에 적합한 새로운 MLCC
조성을 최적화하고자 하였다.
Key Words : Nano BaTiO3, MLCC, Additives, Depressor, Core-shell
*E-mail : [email protected]
Contact Phone : 010-4514-1489
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-98
4상 혼합 유전체 기판 소재의 상 분율에 따른 미세구조와 기계적 강도
Chang Hyun Lee1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Hyo Tae Kim1, Sahn Nahm2
1DAdvanced Materials Convergence Division, Korea Institute of Ceramic Engineering &
Technology, Seoul 153-8012Department of Materials Science and Engineering, Korea University, Seoul 136-701
LTCC는 낮은 저항의 Cu와 Ag 전극을 세라믹 기판 소재와 동시 소성하는 소재 및 공정기
술로써 적층이 용이하고 RF 특성이 뛰어나 전자기기 부품 및 기판 소재로 많이 이용된다. 그
러나 휴대용 전자기기용 부품은 이전에 전자부품들에서 요구되지 않은 고강도와 고열전도도
같은 물리적 특성이 요구되고 있다. 하지만 glass 상을 포함하는 LTCC 소재는 이러한 물리적
특성이 취약하다는 단점을 가지고 있다. 이를 극복하기 위하여 결정화 glass와 알루미나 filler
를 이용하여 물리적 특성을 높이고자 하는 연구들이 많이 진행되어왔다. 그러나 여러 가지 결
정상의 공존에 따른 상분율과 물성의 관계에 관한 연구는 거의 보고되지 않았다. 따라서 본
연구에서는 Anorthite glass, Anorthite 결정, Diopside 결정 및 알루미나 상이 공존하는 조성 영
역을 찾고자 하였으며 이때 각각의 상분율 변화에 따른 기판 소재의 물리적 특성을 비교하고
자 하였다. 소결한 시편은 FE-SEM을 이용하여 미세구조를 확인하였고, X-선 회절분석을 이용
하여 상 분율을 분석하였으며 각 조성은 3점 곡강도를 측정 평가하였다.
*E-mail : [email protected]
Contact Phone : 02-3282-2499
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-99
ZnO-B2O3계 glass 첨가에 따른 Ca[Li1/3Nb2/3)0.8Ti0.2]O3-δ
세라믹스의 마이크로파 유전특성
Chi-Seung In1,2, Dong-Hun Yeo1*, Hyo-Soon Shin1, Sahn Nahm2
1Engineering Ceramic Team, Korea Institute of Ceramic Engineering & Technology,
Icheon 467-843, Korea2Dept, of Materials Science and Engineering, Korea University, Seoul 136-701, Korea
이동통신 단말기의 발달로 소형화, 고기능화가 요구되면서 저손실 특성을 지닌 마이크로
파 유전체가 고주파 통신용 부품들이 널리 이용되고 있다. 이러한 마이크로파 유전체는 고주
파 부품의 복합화 경향에 따라 Ag, Cu 전극과 동시소성이 가능하여야 하며, 다양한 유전율 대
역에서 낮은 손실을 갖는 소재가 요구되고 있다. 유전율 40대역에서 품질계수가 16000, τf 10
으로 우수한 마이크로파 유전특성을 지닌 Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ 조성은 소결온도가 1175 로
높아 Ag 전극과 동시소성이 어렵다. 따라서 본 연구에서는 Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ 조성에
ZnO-B2O3계 glass를 첨가하여 소결온도를 900 이하로 낮추고 우수한 마이크로파 유전특성을
나타내는 조성을 찾고자 하였다. CLNT와 glass 함량 변화에 따른 소결거동, 결정상, 그리고 미
세구조를 확인한 후, 그에 따른 유전특성 변화를 관찰하여 유전체 필터 소재로서의 적용 가능
성을 확인하였다.
*E-mail : [email protected]
Contact Phone : 031-645-1301
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-100
Influence of some metal electrodes on dielectric properties of PTC ceramic
thermistor
Myoung Pyo Chun1*
1Korea Institute of Ceramic Engineering and Technology (KICET), Seoul 153-801,
Republic of Korea
The influence of three different metal electrodes on the electrical and dielectric properties was
investigated with XRD, TEM and impedance analyzer. Two electrodes, Ni-Cu/Ag and Al/Ag, were
deposited by sputtering method and the other electrode, Ag-Zn, was formed by thick film method.
Resistivity at room temperature is 28 , 104 and 253 for Ni-Cu/Ag layered electrode,
Ag-Zn electrode and Al/Ag layered electrode, respectively. From the temperature dependence of
dielectric constant, Curie temperature is different among three metal electrodes with 117oC, 108oC
and 253oC for Ni-Cu/Ag layered electrode, Ag-Zn electrode and Al/Ag layered electrode,
respectively, which seems to be related with thermal residual stress applied by thermal mismatch
between ceramic and metal layers. Thin film Ni-Cu/Ag layered electrode with lower thermal
residual stress exhibited better electrical and dielectric properties than two other ones.
*E-mail : [email protected]
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-101
High Performance Lead Free Piezoelectric Ceramic Composite
S. M. Jang* and S. J. Jeong
Korea Electrotechnology Research Institute, Changwon 642-120
In view of the current demand for global environmental protection, lead-free materials are an
important topic in studies of piezoelectric materials. Sodium-potassium-niobate (Na,K)NbO3 and
bismuth-sodium-titanate (Bi0.5Na0.5)TiO3 systems are promising ceramic families, which might soon
replace lead-based systems.
For better performance, the concept of Bismuth-based ceramic/ceramic composite was proposed.
The composite was made of relaxor matrix with ferroelectric inclusion. The phase transition was
induced by applying an external field for relaxor grains, resulting in large polarization change and
strain.
*E-mail : [email protected]
Contact Phone : 010-9649-8666
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-102
The study of thermoelectric properties in cobalt silicide/silicon thin film
thermoelectric devices
Soojung Kim1,2, Hyundal Jung1, Wonchul Choi1,3, Junsoo Kim1, Dongsuk Jun1,
Taehyoung Zyung1,2 Taekwang Kim1, Eun-su Nam1 and Seungen Moon11,*
1Energy Harvesting Devices Research Section, ETRI, Daejeon 305-700, Korea2Department of Advanced Device Technology, UST, Daejeon 305-350, Korea
3Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea
For the improvement of the energy conversion efficiency in thermoelectric power devices, the
low dimensional thermoelectric materials are studied in many groups. Recently, the specially
designed silicon thin films (SiTFs) including a repeating hole patterns exhibited lower thermal
conductivity and higher ZT value because the phonon scattering increased at interfaces. [1, 2] Here,
we specially designed silicon thin film including the patterned cobalt silicide and compared the
thermoelectric properties of silicon thin film with the cobalt silicide/silicon thin film. The patterned
cobalt silicide can protect reduce the thermal conductivity by scattering the phonon. Also, the
structure is able to enhance Seebeck coefficient because of the high energy carriers which penetrate
the energy barrier between silicon and silicide. Therefore, the figure of merit ZT value can be
increased by this structure. The size width and length of silicon/silicide thin film was set to 20
× 40 , thickness was 70 nm and the implantation dose was × . And then, the 70 nm
diameter cobalt-silicide patterns having interval 140 nm were formed in silicon thin film. As a
results, the maximum seebeck coefficient was 232.03 /K and power factor was
which are higher than that of 70 nm silicon thin film. This is the first study to show that the
silicon/silicide thin film can be used for thermoelectric material.
[References]
1. Yu, J.-K., Mitrovic, S., Tham, D., Varghese, J., Heath, J. R., “Reduction of Thermal Conductivity in
Phononic Nanomesh Structures”, Nat. Nanotechnol., 5, 718-721 (2010)
2. Tang J., Wang H. T., Lee D. H., Fardy M., Huo Z., Russell T. P., and Yang P., “Holey Silicon as
an Efficient Thermoelectric Material”, Nano Lett., 10, 4279-4283 (2010)
*E-mail : [email protected]
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-103
Thermoelectric properties of sputtered silicon membrane in vertical direction
Junsoo Kim1, Wonchul Choi1,3, Soojung Kim1,2, Taekwang Kim1, Hyundal Jung1,
Dongsuk Jun1, Taehyoung Zyung1,2, Seung-Min Lee4, Eun-su Nam1 and Seungen Moon1,*
1Energy Harvesting Devices Research Section, ETRI, Daejeon 305-700, Korea2Department of Advanced Device Technology, UST, Daejeon 305-350, Korea
3Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea4Hanbeam co., Suwon, 443-270, Korea
Silicon thermoelectricity has been widely researched to replace the conventional thermoelectric
materials, for instance, bithmuth telluride because that kind of materials are too rare and expensive
to commercialize1. To enhance the thermoelectric properties, nano-technology has been extensively
applied due to the fact that the nano-sized materials that can scatter the phonon by acoustic phonon
mismatch or geometrical nano-patterns without loss of electrical conductance so the silicon which is
most convenience to fabricate in nano-size and also has thermoelectricity becomes promising
materials for alternative material of bithmuth telluride2. However, the thermoelectricity of vertical
direction of the thin silicon membrane, the basic structure of silicon thermoelectric device, has
rarely been reported due to the difficulty of measuring the small voltage and temperature
differences. Here, we introduce the MEMS technique to measure the thermoelectric properties of
silicon nano-membrane with fine lithography techniques. To minimize the contact resistance and
extract the reliable signals, we designed 6 layers including TCR(Temperature Coefficient of
Resistance) sensors, insulating layers, heater, and silicon membrane using photo-lithography and lift
off process. The TCR and the Seebeck voltage are measured at the room temperature with high
vacuum environment to avoid heat loss by convection. The signals have sufficient reliability and
low errors, and finally Seebeck coefficient can be calculated. This technique provides easy and
precise route to measure the thermoelectric properties of membrane type of various thermoelectric
materials using conventional MEMS technique.
[References]
1. Yu, J.-K., Mitrovic, S., Tham, D., Varghese, J., Heath, J. R., “Reduction of Thermal Conductivity in
Phononic Nanomesh Structures”, Nat. Nanotechnol., 5, 718-721 (2010)
2. Z. Li, S. Tan, E. Bozorg-Grayeli, T. Kodama, M. Asheghi, G. Delgado, M. Panzer, A. Pokrovsky, D.
Wack, and K. Goodson, Nano Lett. 12, 3121–3126 (2012)
*E-mail : [email protected]
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-104
Low Power Consumption and High Sensitive Micro Alcohol Gas Sensor based
on Co-planar Micro-heater and Screen Printing Technique
S. E. Moon1*, T. K. Kim1, J. S. Kim1, W. C. Choi1, B. H. Park2, J. C. Kim2, J. J.
Jung3 and D. J. Yoo3
1Information & Communications Core Technology Research Laboratory, ETRI, 138
Gajeong-ro, Yuseong-gu, Daejeon 305-7002Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701
3Sentech Korea, Sinchon-dong 21-6, Jimokro 75-gil, Paju-Si, Gyeonggi Do, 413-170
Small scale, low power consumption and high sensitive alcohol gas sensor based on SnO2
powders was fabricated by using CMOS compatible MEMS process. High-quality poly-crystalline
SnO2 based powders were made by using co-precipitation method. Their structural properties were
confirmed by using XRD, EDAX, and SEM. To activate the chemical absorption and desorption for
alcohol gas, micro-heater was embedded in the micro gas sensor, which was made by using
CMOS-MEMS process. To acquire the simple fabrication and low fabrication cost, micro-heater and
sensing electrode was located in the same plane. The response of the micro gas sensor was 0.2 for
4 ppm alcohol with lower power consumption (35 mW) than that of the commercial alcohol gas
sensor.
*E-mail : [email protected]
Contact Phone : 052-259-1930
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-105
-20 -15 -10 -5 0 5 10 15 20 25 3010-15
10-13
10-11
10-9
10-7
10-5
10-3
sat
Vd = 0.1 V
(b)
I ds (A
)
Vg (V)
Vd = 15 V
lin
0
10
20
30
40
50
60
Mob
ilti
y,
(cm
2 /V·s
)
Fabrication and Field Effect Electronic Properties of Amorphous ZnO-SnO2
Superlattice Thin Films
Su-Jae Lee, Chi-Sun Hwang, Jae-Eun Pi, and Kyoung-Ik Cho
Smart I/O platform Research Department, ETRI, Taejeon, Korea
Amorphous ZnO-SnO2 superlattice thin films consisting of ZnO and SnO2 layers were
produced by alternating the pulsed laser ablation of ZnO and SnO2 targets, andtheir structural and
field effect electronic transport properties were investigated as a function of the thickness of the
ZnO and SnO2 layers. The performance parameters of amorphous multilayered ZnO-SnO2
superlattice thin film transistors(TFTs) are highly dependent on the thickness of the ZnO and SnO2
layers. The highest electron mobility of 43 cm2/V s, a low subthreshold swing of a 0.22V/dec.
threshold voltage of 1V, and a high drain current on-to-off ratio of 1010 were obtained for the
amorphous multilayered ZnO(1.5nm)-SnO2(1.5nm) superlattice TFTs, which are enough to operate
next-generation microelectronic devices. These results are presumed to be due to the unique
electronic structure of an amorphous multilayered ZnO-SnO2 superlattice film consisting of ZnO,
SnO2 and ZnO-SnO2 interface layers.
Fig. 1. (a) High-resolution cross-sectional STEM images and (inset) SAED patterns, and (b)
Transfer Ids-Vg characteristics and the filed effcct electron mobility(m) of amorphous ZnO-SnO2
superlattice thin films
*E-mail : [email protected]
Contact Phone : 042-860-5504
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-106
ALD 방법으로 증착된 Al2O3 박막의 열전도도 측정
Wonchul Choi1,3, Soojung Kim1,2, Hyundal Jung1, Junsoo Kim1, Dongsuk Jun1,
Taehyoung Zyung1,2, Eunsoo Nam1, Seungmin Lee4, and Seungen Moon1,*
1Energy Harvesting Devices Research Section, ETRI, Daejeon 305-700, Korea2Department of Advanced Device Technology, UST, Daejeon 305-350, Korea
3Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea4Hanbeam Co. Suwon 443-270, Korea
최근 반도체 기술이 발달함에 따라서 MOSFETs의 절연막에 대한 관심이 늘어나고 있다.
Metal gate 영역과 silicon의 사이에 존재 하는 절연막은 SiO2의 높은 퀄리티로 현재까지 소자
의 사이즈 축소에 큰 영향을 끼쳐 왔다. 하지만 사이즈가 점점 더 작아지면서 SiO2 박막의 두
께에도 한계가 오자 high-k 물질로 이를 대체 하려는 시도가 이어져 왔다.1 High-k 물질을 높
은 순도 및 커버리지를 위하여 ALD로 증착 하려는 노력이 지난 20년간 이어져 왔다. 하지만
ALD로 증착된 high-k 물질에 대한 열 물성에 대한 분석은 충분히 이루어지지 않았다. 이는 박
막의 열전도도 측정이 벌크 물질의 측정과는 다르며 매우 까다롭기 때문이다. 박막의 열전도
도를 측정하기 위해서는 벌크 물질과는 다른 방법이 요구 된다. 본 연구에서 Al2O3 박막의 열
전도도를 측정하기 위해서 우리는 3ω 방법을 이용하여 열전도도를 측정 하고자 한다. 3ω 방
법은 박막의 열전도도를 측정 하는 방법중에 널리 알려진 방법으로써 많은 연구가 이루어지
고 있다.2 이 방법을 이용하여 다양한 온도 영역에서의 Al2O3 박막의 열전도도를 측정 하였다.
ALD 방법으로 증착되어 비교적 높은 밀도를 갖는 Al2O3 박막의 열전도도 특성을 알아보고자
한다. 증착된 박막의 밀도 및 두께 등을 분석 하였다. 이는 MOSFET소자의 gate 절연막으로
사용될때 열적 특성을 분석을 가능하게 하여 Al2O3를 gate 절연막으로 사용하는 MOSFET의 열
분석에 도움을 줄 것으로 기대 된다.
[References]
1. Zhu, W.J., Ma, T.-P., Tamagawa, T., Kim, J., Di, Y., "Current transport in metal/hafnium oxide/silicon
structure", Electron Device Letters, IEEE, 97 - 99 Volume: 23, Issue: 2, Feb. 2002
2. Jiezhu Jin, Mohan P. Manoharan, Qing Wang, and M. A. Haque, "In-plane thermal conductivity of
nanoscale polyaniline thin films", APL, 95, 033113 2009
*E-mail : [email protected]
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-107
[그림 16] PDMS의 음속도의 압력에 따른
의존성.
고압 브릴루앙 산란을 이용한 Polydimethylsiloxane의 고압특성 분석
신선협1, 고재현1*, 고영호2, 김광주2
1200-702 강원도 춘천시 한림대학교 전자물리학과2305-152 대전광역시 유성구 국방과학연구소 4본부 2부
Polydimethylsiloxane(PDMS)는 실리콘 기반 유기 고분자의 일종으로써 압전 소자를 포함해
광범위한 분야에 적용되고 있는 재료로 잘 알려져 있다. 이런 재료의 적절한 응용을 위해서는
다양한 열역학적 변수의 광범위한 변화 하에서 다양한 물성을 획득해야 한다. 본 연구에서는
PDMS의 고압 환경 하에서의 탄성데이터를 고압 브릴루앙 산란법을 이용해 구하였다. 브릴루
앙 산란법은 응집물질 내 음파의 속도를 측정하여 물질의 굴절률, 탄성 계수 및 비정질 물질
의 경우에는 밀도까지 파악 할 수 있는 실험 방법이다. 압력은 물질의 밀도를 증가시키면서
원자간 퍼텐셜(interatomic potential) 및 이에 따른 탄
성 특성에 커다란 변화를 유도하기 때문에 음속도-
압력 등 다양한 특성을 압력에 대한 함수로 구할
수 있다. 본 연구에서는 압력을 주는 장치로
Diamond anvil cell(DAC)을 활용하여 0~10 GPa의 압
력 범위에 걸쳐서 브릴루앙 산란실험을 진행하였다
[1]. [그림 1] 에서와 같이 음속도는 압력 인가에
따라 현저하게 증가하는 형태를 보였고 굴절률은
상압에서 n 1.4값과 10 GPa에서 n 1.6의 값을 얻
었다. 이러한 데이터 분석을 통해 PDMS의 압력에
따른 굴절률 데이터를 구하였다.
* 본 연구는 방위사업청과 국방과학연구소의 연구
지원에 의한 것임을 밝힙니다.
[1] J. H. Kim, J. -Y. Choi, M. -S. Jeong, J. -H. Ko, M. Ahart, Y. H. Ko, and K. J. Kim, J. Korean
Phys. Soc. 60, 1419-1423 (2012).
*E-mail : [email protected]
Contact Phone : +82-33-248-2056
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-108
-200 0 200 400 600 800 100048
50
52
54
Bril
loui
n S
hift
(GH
z)
Temperature (oC)
LA mode Ta mode
0
1
2
3
4
FW
HM
(G
Hz)
Phase Transition Behaviors of Lead-Free (NaBi)TiO-BaTiO Single
Crystals Studied by Inelastic Light Scattering Spectroscopy
Byoung Wan Lee1, Jun Ho Ryeom1, Jae-Hyeon Ko1, Xiaobing Li2 and Haosu Luo2
1Department of Physics, Hallym University, Hallydaehakgil 1, Chuncheon 200-702, Korea2Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China
Lead-free piezoelectric materials have recently attracted great attention due to their
environmentally-friendly aspect in spite of the fact that their piezoelectric performances are
generally inferior to those of lead-based piezoelectrics, such as Pb(Zr1-xTix)O. It is of
paramount importance to understand the nature of phase transition behaviors of these materials
in order to get more insights into the way how we can improve the piezoelectric
performances of lead-free piezoelectric materials. Brillouin scattering spectrum of 0.95(NaBi
)TiO-0.05BaTiO (NBT-BT) single crystals was investigated in a wide temperature range
along different crystallographic axes. The crystals were grown by carefully controlled
top-seeded solution growth method[1], and the Brillouin spectrum was measured by using
conventional tandem 6-pass Fabry-Perot interferometer [2]. The temperature dependence of the
longitudinal acoustic (LA) mode frequency showed softening over a large temperature range,
which was most substantial for the LA mode propagating along the [100] direction. The onset
temperature of the mode softening was approximately 800 , and the LA mode frequency
exhibited a minimum near 250 and then increased on further cooling. This softening of
the LA mode was accompanied by substantial increase in the half width, as well as growth
of the quasielastic central peak. The acoustic damping also became the largest for the LA
mode along the [100] direction. These acoustic
anomalies indicate the formation and evolution of
noncentrosymmetric polar clusters in the
paraelectric phase of NBT-BT single crystals.
These acoustic behaviors will be compared to
other electric properties such as dielectric
constant.
*E-mail : [email protected]
Contact Phone : 033-248-2056
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-109
Phase transition behaviors of PbZr0.8Ti0.2O3 single crystals as revealed
by elastic anomalies and central peaks
Min-Seok Jeong1, Jae-Hyeon Ko1*, Seiji Kojima2, Alexei A. Bokov3, Xifa Long3,
and Zuo-Guang Ye3
1Dept. of Physics, Hallym Univ., Chuncheon, Gangwondo 200-702, Korea2Institute of Materials Science, Univ. of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
3Dept. of Chemistry and 4D LABS, Simon Fraser Univ., Burnaby, BC V5A 1S6, Canada
The acoustic phonon and central peak behaviors of PbZr0.8Ti0.2O3 single crystals were
investigated by Brillouin light scattering. The Brillouin frequency shift of the longitudinal acoustic
mode showed a substantial softening at the Curie temperature (~305oC) and the tilting phase
boundary (~127oC). The transverse acoustic mode appeared at the Curie point, indicating a clear
structural phase transition. Fig. 1 shows the temperature dependence of the intensity and the full
width at the half maximum (FWHM) of the quasi-elastic central peak of PbZr0.8Ti0.2O3. The change
in the intensity and FWHM has strong correlation with the two structural phase transitions. The
decrease in the FWHM indicates the slowing down behavior of the relevant polarization
fluctuations.
Fig.1 Temperature dependence of the intensity and the FWHM of the quasi-elastic central peak.
*E-mail : [email protected]
Contact Phone : +82-33-248-2056
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-110
Instability of Reset Parameters Due to Intrinsic Property of Conducting
Filaments Formed at Low Compliance Current in Unipolar Resistance
Switching
Sang-Chul Na1, Keundong Lee2, Min Chul Chun1, Young-Sun Kwon1, Hye-Jin Shin1, Ji
Seok Im1, Sangik Lee2, Bae Ho Park2 and Bo Soo Kang1*
1Department of Applied Physics, Hanyang University, Ansan 426-7912Division of Quantum Phases & Devices, Department of Physics, Konkuk University,
Seoul 143-701
Numerous studies on the resistance switching (RS) have been intensively conducted due to the
great potential of the application to the next-generation nonvolatile memory. There are two
switching processes in the RS, set and reset processes. The reset process means a resistance
transition from the low resistance state (LRS) to the high resistance state (HRS), while the set
process stands for a reverse reaction. In the point of practical view, higher resistance of the LRS
(RL) which is made by setting low compliance current (CC) is preferred due to low power
consumption for the reset process. However, it is generally known that the reset current (Ireset) and
voltage (Vreset) has a wide distribution when the RL is relatively high. This fact is one of serious
problem that hinder the memory application.
In this study, the reset parameters and the RL depending on CC were investigated in a
Pt/NiO/Pt thin film showing the unipolar resistance switching. Controlling CC was properly
employed to manage the connectivity of the conducting filaments (CFs). The Ireset and the Vreset at
low CC seriously fluctuated. We proposed two possibilities, the overshoot current during the set
process and an intrinsic problem coming from the CFs formed at low CC, to explain the physical
origin of the instability of the reset parameters at low CC. Combining the simple simulation and
the results eliminated the overshoot current, we could conclude that the Ireset and the Vreset fluctuated
because of the number and width variations of the CFs at low CC.
*E-mail : [email protected]
Contact Phone : 010-7108-3696
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-111
The Effects of Etch Stopper Layer on Electrical Properties of Tin monoxide
Thin Film Transistors Prepared by RF Magnetron Sputtering
J.-Y. Kim1, J.-M. Song2, K. M. Yu1, B. S. Bae1, and E.-J. Yun2,3*
1Dept. of Display Engineering, Hoseo University, Asan, 336-7952Dept. of System Control Engineering, Hoseo University, Asan, 336-795
3Dept. of Information and Communication Engineering, Hoseo University, Asan, 336-795
Recently, amorphous oxide semiconductors (AOSs) have attracted extensive attention from many
researchers. Many studies related to AOS-based thin-film transistors (AOS-TFTs) have also been
reported. The use of AOS-TFTs is expected to be a promising solution to meet market
requirements because they have a high field-effect mobility comparable with that of a-Si TFTs and
low production costs comparable with those of poly-Si:H TFTs. However, AOS-TFTs have been
limited to the n-type channel type because they have superior n-type characteristics compared to
p-type ones. Therefore, p-type AOS-TFTs are still at the initial research stage. The use of
complementary metal oxide semiconductor (CMOS) circuits composed of p- and n-channel TFTs is
necessary for fabricating high-performance integrated circuits (ICs) on glass substrates. Periphery
circuits on glass substrates, such as gate-driver ICs and data-driver ICs, have become an essential
part of high-performance display devices. Therefore, the development of p-channel AOS-TFTs is
necessary for making oxide semiconductor technology practical. A tin monoxide (SnO) has been
received a particular attention because of its high possibility in obtaining high quality p-type AOSs.
In this study, we fabricated p-type SnO-based TFTs by a more TFT-industry-compatible sputtering
from a SnO target. Then, some TFTs were post-annealed at 300 °C in N2 ambient. We used the
etch stopper layer (ESL), which acts as a passivation layer, to protect the surface of the SnO
channel layer. We systematically compared the time-dependent device properties of TFTs with ESL
to those without ESL. This comparison gave insight on the effect of ESL on the electrical
properties and the long-time stabilities of the SnO-TFTs.
*E-mail : [email protected]
Contact Phone : 010-2661-8005 (041-540-5675)
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-112
A Study on the High Temperature-dependence of Electrical Properties in
Solution-deposited Zinc Tin Oxide Thin Film Transistor Operated in the
Saturation Region
K. M. Yu1, B. S. Bae1, and E.-J. Yun2*
1Dept. of Display Engineering, Hoseo University, Asan, 336-7952Dept. of Information and Communication Engineering, Hoseo University, Asan, 336-795
Nowadays, solution-processed amorphous zinc tin oxide (a-ZTO) thin films have attracted notable attention as a channel layer in fabrication of flexible low-cost roll-to-roll printed thin film transistors (TFTs) because of their high field-effect mobility, which is possibly larger than 25 cm2/Vs, and their simplicity, low-cost, high throughput, and non-toxicity. a-ZTO thin films also possess very interesting charge transport characteristics which range from thermally-activated transport at low mobility and low carrier densities to extended state (or band) transport at high mobility, large carrier densities and low temperatures. Indeed, a-ZTO is one of the most interesting semiconductor materials in terms of charge transport, as it is at the cusp between thermally activated and band transport, exhibiting a mobility edge. a-ZTO is also the first amorphous material that possesses such a range of transport behavior as a function of field-induced carrier density. Therefore, a full picture of charge transport in this unique a-ZTO thin films needs to be developed. Moreover, there have been no clear reports of band transport and documentation of mobility edge behavior in any solution-processed amorphous semiconductor. Thus, in this paper, we investigated charge transport studies at temperatures in the range of 303 402 K in the solution-deposited a-ZTO TFTs operated in the saturation region. The developed TFTs had a bottom-gate and top contact structure, which used a heavily-doped Si wafer and a 300-nm-thick SiO2 as a gate electrode and a gate insulator layer, respectively. The channel width and the channel length of TFTs were 1500 and 100 µm, respectively. As a ZTO channel layer, zinc acetate dehydrate and tin chloride were mixed in 2-methoxyethanol to form a sol-gel solution mixture stabilized by an ethylamine. The 40-nm-thick ZTO channel layers were obtained by annealing at 600 °C for 1 hour in a furnace. In a-ZTO channel, the trap release energy (ETR) was estimated using Fermi-Dirac statistics and the Maxwell-Boltzmann approximation. The decreasing the ETR with increasing density of trap states (ns) can be understood by a shift of the Fermi level toward the mobility edge and the shapes of ns fit very well to exponential function, indicating that the experimental data in the insulating regime well agreed with the modified multiple trap and release model and show the thermally activated behavior which is related to the increase of mobility with increasing temperature. It was found that the use of Fermi-Dirac statistics instead of Maxwell-Boltzmann statistics is important in accurately determining the ETR.
*E-mail : [email protected]
Contact Phone : 010-2661-8005 (041-540-5675)
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-113
High Temperature Dielectric Relaxations in BiFeO3-(Bi,K)TiO3 Ceramics
Jung Hwan Kim1, Jeong Seog Kim2, Wook Jo3, Chae Il Cheon1∗
1Department of Materials Science & Engineering and 2Department of Digital
DisplayEngineering, HoseoUniversity, Asan, Chungnam 336-795 Korea3Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
BiFeO3-(Bi,K)TiO3 (BF-BKT) ceramics has been reported to demonstrate outstanding
ferroelectric and piezoelectric properties; a large remanent polarization of about 50μC/cm2 and a
moderate electro-mechanical coupling factor (k33) of 0.3~0.35 at phase boundaries between
ferroelectric rhombohedral and pseudocubic. However, there is large variance among
temperature-dependent dielectric properties reported in literatures. Relaxor-like dielectric properties,
i.e., broad dielectric maximum with frequency dispersion, have been observed in the pseudocubic
composition range and claimed to originate from nanosized polar domains. And a Maxwell-Wagner
type dielectric relaxation was also observed in a BF-BKT ceramic below 300oC in BF-rich
rhombohedral compositions.
The dielectric relaxations due to extrinsic effects have been observed in many perovskite
titanates compounds; Maxwell-Wagner relaxation at grain boundary and/or contact electrode in
ferroelectric super-lattice thin films and CaCu3Ti4O12 (CCTO), and Debye-type dipolar relaxation due
to oxygen vacancies in BaTiO3, (Pb,La)TiO3, Pb(Mg,Ni)O3-PbTiO3, and CCTO at 300oC~700oC. The
extrinsic dielectric relaxations are expected in BF-BKT ceramics as well and could make an
understanding on the temperature-dependent dielectric behavior difficult.
In this work, the temperature-dependent dielectric behavior was investigated in BF-BKT
ceramics. Dielectric constant and the corresponding loss factor were measured in the temperature
range of RT to 650oC at various frequencies. Extrinsic dielectric relaxations were observed at
around 300~600oC. Impedance spectroscopy was utilized for understanding the origins of the
relaxations. Dielectric relaxations in BF-BKT ceramics sintered under various atmospheres such as
air, oxygen, and nitrogen have been compared to clarify the origins of the extrinsic dielectric
relaxations.
*E-mail : [email protected]
Contact Phone : 041-540-5763
강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비
P-114
First-principles Investigation of Bistability in Ga- and In-doped CdF2
M. S. Kim1* and C. H. Park1,2
1Research Center for Dielectric and Advanced Matter Physics, Department of Physics,
Pusan National University, Busan 609-7852Research Center for Dielectric and Advanced Matter Physics, Department of Physics
Education, Pusan National University, Busan 609-785
In II-V and II-VI znic blende semiconductors, one of the well-known phenomena is a
bistability in which a dopant atom has both highly localized deep and shallow states. Amazingly,
the same type of bistability is reported for Ga- and In-doped CdF2 in fluorite structure and the
discovery of bistability in large-band-gap materials can open the way for novel applications such as
photorefractive medium. However, the theoretical understanding is still controversial. Here, we report
the electronic structure of Ga- and In-doped CdF2, and the bistability of atomic structure around In,
Ga, and Tl in CdF2, based on the screened hybrid functional method.
*E-mail : [email protected]
Contact Phone : 051-510-2959
후원업체 소개
회사명 (한맥전자(주))대 표 자 한맥전자(주)전 화 02-467-7447 팩 스 02-467-6816이 메 일 [email protected] 홈페이지 http://hanmacco.com주 소 서울시 성동구 성수1가 2동 16-4번지 SK 테크노빌딩 1001호
․ 회사소개 저희 한맥전자(주)는 1988년부터 외국의 첨단 계측장비를 대학, 연구소, 반도체, 디스플레이, 정보통신, 전기, 전자 및 자동차 관련 산업체 등에 판매를 하여왔습니다.첨단 계측장비를 공급 및 기술 지원을 하면서 습득한 신기술을 바탕으로 1994년에 부설 기술연구소를 설립하여 PDP화상평가장치, 3D Laser 화상입력기 및 원격검침 장치를 개발하였습니다.미래지식 산업체의 일원으로 성장하기 위해 최선을 다하고 있으며, 신속한 기술지원으로 고객으로부터 신뢰받고 주주와 종업원에게 이익과 만족을 주며 지속적으로 성장하는 건강한 회사가 되고자 합니다.
․ 전시품명1) High Voltage Power Amplifier2) Function Generator
․ 제품특징1) High Voltage Power Amplifier
0 - 50kV의 넓은 대역의 Line-upApplication PIEZO, Ferro-electric, Hysterisys
2) Function Generator