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Electronic Materials & Devices LaboratorySeoul National UniversityDepartment of Material Science & Engineering
Lithium Disilicate Glass-ceramics
for dental applications
March, 14, 2016
Department of Materials Science and Engineering,
Seoul National University
Supervisor : Prof. Sang-Im Yoo
Dami KIM
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
2/40Contents
1. Introduction
2. Research Subtopics
I-1. Crytallization of lithium disilicate glass-ceramics by mixture design
I-2. Effect of crystallization on mechanical properties of lithium disilicate
glass ceramics
I-3. Effect of the colorants on the color and translucency of lithium
disilicate glass-ceramics
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
3/40
3
Posterior teethAnterior teeth
Introduction : Properties of Human teeth
<Color of human tooth>
L* a* b*
66.2± 3.6 2.6±1 14.4±3.9
<Translucency of human tooth>
Ref) Rubino, M et al, Color Research & Application 19 (1994) 19-22
<Toughness & Hardness of human teeth>
http://www.glidewelldental.com/images/dentist/chairside/v7-4/articles/zirconia-veneer/lightbox/Fig18.jpg
Enamel : Blue/White Opalesence & Fluorescence
GPa5.4
m MPa5.4 1/2
≈
≈
Ref (https://en.wikipedia.org/wiki/Tooth_enamel
Ref) V.Imbeni, Nature. Mat. 4 (2005) Ref) Yong-Keun Lee, J. Biomed. Opt 20(4)
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
4/40
4
Introduction : Dental Materials
Amalgam
Metal crown
Fracture occured (Porcelain : 75~100MPa)PFM(Porcelain Fused metal) crown
All-ceramic crown
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
5/40
5
<Translucency>
<Dental Implant>
Single crown 3-unit Bridge
Introduction : Dental ceramics
0
200
400
600
800
1000
1200
1400
Leucite GC
(IPS Empress)
Lithium Disilicate
(IPS e.max)
Alumina
(Procera)
Zirconia
(Lava)Fl
exu
ral st
rength
(M
Pa)
• High strength
• Moderate hardness
• Excellent esthetics
- Shade(color)
- Translucency
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
6/40
6
Introduction : Manufacturing of Crown
<Hot-Pressing : LS2 GC> <CAD/CAM : Zirconia, Alumina, LS GC>
Zironia block
LS2 Ingot
Plastic deformation of
LS2 GC (softening)
Hot-pressing furnace
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
7/40
7
Introduction : Lithium disilicate glass-ceramics
21%
18%
13%9%8%
6%4%
21%
Companies of Crowns and Bridge
Ivoclar Vivadent AG Noritake Co., Limited
Dentsply International Inc. SHOFU INC.
3M ESPE Dental Products Nobel Biocare Holding AG
VITA In-Ceram Others
Benchmarking!
Shade (color) Translucency
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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8
Optimal crystallization condition Shade & TranslucencyPlastic deformation (Softening)
Manufacturing condition
Part. I
To obtain optimal crystallization condition for LS2 GC by design of composition through mixture design.
To identify the appropriate heat-treatment condition.
Part. II Part. III
To fit the shade and
translucency of
Benchmarking product.
(Ivoclar vivadent)
To study about plastic
deformation behavior
of LS2 GC for hot-
pressing condition.
Motivation & Objective
Development of suitable composition design and estabilishment of heat-treatment
condition to obtain 400MPa flexural strength of lithium disilicate glass-ceramics with
various color, translucency and feasibility of plastic deformation.
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
9/40
I-1. Crytallization of Lithium Disilicate
Glass-Ceramics by Mixture Design
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
10/40
10
Part I-1. Motivation & Objective
Roles Additives Details
Nucleation
reagent
P2O5Bulk Crystallization
ZrO2Additives for mechanical strength
TiO2Surface Crystallization
Pt, Pd, Au, Ag Surface/bulk Crystallization
Glass
network
Former
&
Modifier
K2O flux
Na2O flux
BaOIncrease of Li2SiO3 crystallization peak
although lead to decrease of Volume fractionCaO
Viscosity
&
chemical
stability
La2O3 ,Al2O3control viscosity and flow in plastic state
MgO, ZnO,
Nb2O3 ,B2O3,
SrO
• Good chemical stability
• Low viscosity to enhance Li2SiO3 crystal
result in moderate fraction
• Deteriorate crystal growth of Li2SiO5
<Additives for LS2><Crystallization of Lithium Disilicate(LS2) Glass>
Ref) Glass and Glass Ceramics for Medical Applications (Emad El-Meliegy) p212~214
RT
G
aN
fRTU exp1
3 2
0
On the basis of mixture design (Design of experimental), the effect of
additives ratio on crystallization of LS2(Li2O∙2SiO2) was studied.
kT
GWAI D )(
exp*
Liquid-liquid phase separation
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
11/40
Additives P2O5 ZnO K2O
Raw materials (NH4)2HPO4 ZnO K2CO3
Role Nucleation agent Glass modifier
• Matrix SiO2/Li2O=2.3 (94mol% fixed)
• Total amount of additives : 6mol%
<Glass composition>
Experimental
0 20 40 60 80 100
0
20
40
60
80
1000
20
40
60
80
100
131211
109876
5432
ZnO
P2O
5
K2O
1
0
200
400
600
800
1000
1200
1400
1600
NucleationAnnealing
Forming
Crystallizaion
Te
mp
era
ture
(oC
)
Time (min)
Melting
Glass fabrication :
Melt-Quenching method
<Experimental>
<Bi-axial strength>
• ISO 6872
• Piston on a 3-balls
• Sample size : 12.8mm(Dia), 1.2T
<Hardness : Vicker’s >
• Indentation load: HV 0.5
• Duration time : 10s
Sample ID
Compositions of
additives (mol%) ZnO/K2O
P2O5 K2O ZnO
#1 1.5 3 1.5 0.5
#2 1.5 2.25 2.25 1
#3 1.5 1.5 3 2
#4 1.25 2.75 2 0.727
#5 1.25 2 2.75 1.375
#6 1 3 2 0.667
#7 1 2.5 2.5 1
#8 1 2 3 1.5
#9 0.75 2.75 2.5 0.909
#10 0.75 2.5 2.75 1.1
#11 0.5 3 2.5 0.833
#12 0.5 2.75 2.75 1
#13 0.5 2.5 3 1.2
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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12
XRD
10 20 30 40 50
13
12
11
10
Inte
nsity (
a.u
.)
2-theta (2)
9
10 20 30 40 50
6
4
8
5
7
3
2
Inte
nsity (
a.u
.)
2-theta (2)
1
Lithium Disilicate [01-072-0102]
Cristobalite – SiO2 [01-071-0785]
0 20 40 60 80 100
0
20
40
60
80
1000
20
40
60
80
100
131211
109876
5432
ZnO
P2O
5
K2O
1
CompositionP2O5 ZnO/K2O(mol%)
1
1.5
0.5
2 1
3 2
41.25
0.73
5 1.38
61
0.67
7 1
8 1.5
90.75
0.9
10 1.1
110.5
0.83
12 1
13 1.2
• The formation of secondary phase cristobalite is thought to
be related to the Zn2+ ion
• The Zn2+ is thought to be located at tetrahedral sites since it
prefers four coordination due to strong covalent boding via
sp3 hybridization
• It is assumed that Zn2+ ions behave as a glass former in the
tetrahedral unit (ZnO4)2- possessing Li+ and K+ to maintain
neutrality in the glass, and therefore the Si-rich region
increases near (ZnO4)2- and is crystallized as cristobalite.
Nucleation agent
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
13/40Microstructure : SEM
0 20 40 60 80 100
0
20
40
60
80
1000
20
40
60
80
100
131211
109876
5432
ZnO
P2O
5
K2O
1
Nucleation agent
0.4 0.8 1.2 1.6 2.00
1
2
3
4 P
2O
5 1.5mol%
P2O
5 1.25mol%
P2O
5 1mol%
Length
ZnO/K2O
0.4 0.8 1.2 1.6 2.01.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
P2O
5 1.5mol%
P2O
5 1.25mol%
P2O
5 1mol%
Aspect ra
tio
ZnO/K2O
Spherulite
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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14
Strength & Hardness
13121110987654321
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
Vic
ker'
s h
ard
ness (
GPa)
0 20 40 60 80 100
0
20
40
60
80
1000
20
40
60
80
100
131211
109876
5432
ZnO
P2O
5
K2O
1
Nucleation agent
13121110987654321
450
400
350
300
250
200
150
100
50
Bi-
axia
l strength
(M
Pa)
ZnO ↑
ZnO ↑
• The Bi-axial strength and hardness increased as increase of P2O5.
• The hardness tend to increase by increase of ZnO.
• The strength and hardness prone to increase as decrease of grain
size. It is thought that the addition of P2O5 provided many sites
of crystalline phase, and the ZnO hinderd the growth of LS2
phase by consuming Li+ Ion.
P2O5 ↑ P2O5 ↑
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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15
Surmmary
15
The crystal size became small as increase of P2O5 due to its increase of
heterogeneous nucleation sites and more spherical as increase of ZnO.
The ZnO affected the formation of cristaobalite by consuming of Li+ ion and the
increase of SiO2-rich phase fraction which is crystallized. Also, it impeded
growth of LS2 crystalline phase.
The bi-axial strength and hardness increased as decrease of crystalline phase size.
I-1. Crytallization of Lithium Disilicate Glass-Ceramics by Mixture Design
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
16/40
I-2. Effect of crystallization on mechanical
properties of lithium disilicate glass ceramics
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
17/40
17
Part I-2. Motivation & Objective
2/1 dkyyf
Y : Crack shape factor
• σf is the yield stress for the easiest slip system of a single crystal
• ky is constant
2/1 cYKI
2/12/1 dY
Kc
Y
K ICICf
2/1
0
dkHH h
Fine-grained branch
<25㎛
<Al2O3-polycrystalline>
Ref) http://www.georgevandervoort.com/metallography/specific/iron-and-steel-
specific/20001306-revealing-prior-austenite-grain-boundaries-in-heat-treated-steels-
article.html
<9310 alloy steel> <4340 alloy steel>
Dislocation Pile-up
Ref) http://www.ceramtec.kr/ceramic-
materials/aluminum-oxide/
<Al2O3> <Li2Si2O5>
<Metal> <Ceramics> <Glass Ceramics>
1. Does the strength and hardness of crystalline phase of LS2 glass-ceramics
follows the Hall-Petch relation?
2. What factors would influence on the strength & hardness of LS2 glass-
ceramics?
<Hall-Petch relation>
<Griffiths eq.>
Hall-Petch relation + Griffiths eq.
Ref) Mechanical properties of ceramics
(John. B. Wachtman) p215
Ref) Wikipedia : Hall—Petch Strengthening
sizeGrain Crack
Assumption)
Grain size, d-1/2
d~10n
m
σ
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
18/40
18
Additives P2O5 ZnO K2O
Raw materials (NH4)2HPO4 ZnO K2CO3
Role Nucleation agent Glass modifier
•SiO2/Li2O=2.3 (94mol% fixed)
• Additives total : 6mol%
<Glass composition>
Heat-treatment affects the number of nuclei, size of
crystalline phase
Nucleation temperature, time → The number of nuclei
- Crystal growth temperature, time→ Crystalline phase size
<Crystallization>
Sample
IDComposition SiO2 Li2O P2O5 ZnO K2O
#3 P1.5Zn3 66.27 27.73 1.5 3 1.5
#4 P1.25Zn2.75 66.27 27.73 1.25 2.75 2
#7 P1.25Zn2 66.27 27.73 1.25 2 2.75
#12 P1Zn2.5 66.27 27.73 1 2.5 2.5
Heating
Tg : 440oC
Tm : 990oC
Ref) http://polymer-additives.specialchem.com/centers/polypropylene-nucleation-
center/how-do-nucleating-agents-work
Experimental
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
19/40
19
<Crystal growth : Heat-treatment condition>
Max. Nucleation Temp. →
Nucleation Temp. Crystal growth Temp. Crystal growth Time
460
8002
4
8502
4
500
8002
4
8502
4
540
8002
4
8502
4
<Strength : Bi-axial >
<Hardness : Vicker’s >
• ISO 6872
• Piston on a 3-balls
• Sample size : 12.8mm(Dia), 1.2T
<Fracture Toughness : SEVNB>
• Single-Edge-V-Notch-Beam
• Notch depth : 1mm, Tip Radius: 15μm
• Sample size : 3 × 4 × 40 (mm)
<3-point>
NotchSpan : 30mm
• Indentation load: HV 0.5
• Duration time : 10s
Isothermal : 1h
Heating rate : 15℃
<Maximum nucleation Temperature>→ Marrota’s DTA analysis
0
0
0
00
0
0
11)ln(
)0( sample quenched-asan for 1
ln
rate heating & surface same
nucleated previouslyfor 1
)ln(
pp
cn
n
p
c
p
cn
TTR
E
N
NN
NconstTR
EN
N
constTR
ENN
raturepeak tempeDTA theofshift pp TTT
→ Max. nucleation rate
Ref) A. Marrota et al, J. Mat. Sci. 16 (1981) 341
• Nucleation duration: : 1h (fixed)
• Heating rate : 10℃/min
• Crystal growth
• Heating rate : : 30℃ /min
Experimental
0
200
400
600
800
1000
1200
1400
1600
NucleationAnnealing
Forming
Crystallizaion
Tem
pe
ratu
re (
oC
)
Time (min)
Melting
Glass fabrication :
Melt-Quenching method
<Experimental>
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
20/40
20/14
Crystal growth
Temp.800oC 850oC
Crystal growth
Time2h 4h 2h 4h
0
460oC
500oC
Max.Nucleation
Temp.
Nu
clea
tion
Tem
p.
10㎛ 10㎛10㎛ 10㎛
10㎛ 10㎛10㎛ 10㎛
10㎛ 10㎛10㎛ 10㎛
length
width
20/14
5004600
850800850800850800
424242424242
14
12
10
8
6
4
2
Length
(㎛
)
Nucleation Temp.
Crystal growth Temp.
Crystal growth Time
5004600
850800850800850800
424242424242
5
4
3
2
1
0
Wid
th (㎛
)
Crystalline phase size : P1Zn2.5
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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21/14
Crystal growth
Temp.800oC 850oC
Crystal growth
Time2h 4h 2h 4h
460oC
500oC
Max.Nucleation
Temp.
540oC
Nu
clea
tion
Tem
p.
5㎛ 5㎛ 5㎛
5㎛
5㎛ 5㎛ 5㎛ 5㎛
5㎛ 5㎛ 5㎛
5㎛
540500460
850800850800850800
424242424242
7
6
5
4
3
2
1
Asp
ect
ratio
Nucleation Temp.
Crystal growth Temp.
Crystal growth Time
540500460
850800850800850800
424242424242
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Wid
th (㎛
)
540500460
850800850800850800
424242424242
4
3
2
1
0
Length
(㎛
)
length
width
Crystalline phase size : P1.25Zn2
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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22/14
Crystal growth
Temp.800oC 850oC
Crystal growth
Time2h 4h 2h 4h
460oC
500oC
Max.Nucleation
Temp.
540oC
Nu
clea
tio
n T
emp
.
5㎛ 5㎛ 5㎛
5㎛
5㎛ 5㎛ 5㎛ 5㎛
5㎛ 5㎛ 5㎛
5㎛
540500460
850800850800850800
424242424242
6
5
4
3
2
1
Asp
ect
ratio
540500460
850800850800850800
424242424242
2.5
2.0
1.5
1.0
0.5
Length
(㎛
)
Nucleation Temp.
Crystal growth Temp.
Crystal growth Time
540500460
850800850800850800
424242424242
1.0
0.8
0.6
0.4
0.2
Wid
th (㎛
)
length
width
Crystalline phase size : P1.25Zn2.75
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Crystal growth
Temp.800oC 850oC
Crystal growth
Time2h 4h 2h 4h
460oC
500oC
Max.Nucleation
Temp.
540oC
23/14
Nu
clea
tion
Tem
p.
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
1㎛
Nucleation Temp.
Crystal growth Temp.
Crystal growth Time
540520460
850800850800850800
424242424242
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Wid
th (㎛
)
540520460
850800850800850800
424242424242
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Length
(㎛
)
length
width
540520460
850800850800850800
424242424242
6
5
4
3
2
1
Asp
ect
ratio
P1Zn2.5 P1.5Zn3P1.25Zn2.75
2㎛ 2㎛
P1.25Zn2
2㎛2㎛
Heat treat-ment : 500oC, 800oC, 2h
Crystalline phase size : P1.5Zn3
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24/14
Lithium Disilicate [01-072-0102]
Cristobalite – SiO2 [01-071-0785]
• From the Li2O-rich region, Li3PO4 was formed and it
promoted the LS2 growth.
• SiO2-rich region may be left as increase of P2O5 and it
formed cristobalite (SiO2).
• ZnO may consumed the Li+ to maintain neutrality in
the glass which result in increase of SiO2-rich region
leading the cristobalite (SiO2) growth.
10 20 30 40 50
P1.5Zn3
P1.25Zn2.75
P1.25Zn2
Inte
nsity (
a.u
.)
2-theta (deg.)
P1Zn2.5
(101)(020)
(110)SiO2/Li2O=2.39
Composition SiO2 Li2O P2O5 ZnO K2O
P1.5Zn3 66.27 27.73 1.5 3 1.5
P1.25Zn2.75 66.27 27.73 1.25 2.75 2
P1.25Zn2 66.27 27.73 1.25 2 2.75
P1Zn2.5 66.27 27.73 1 2.5 2.5
• Secondary phase cristobalite peak increased as increase of P2O5 and ZnO.
• P2O5 induced phase separation the Li2O-rich region and SiO2-rich region.
<Phase separation>
Ref) Glass-ceramics technology (Wolfram Hölnad) p50
Crystalline phase analysis : XRD
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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25/14
1129
2.8
2.6
2.4
2.2
2.0
1.8
Fra
ctu
re t
oughness (
MP
a m
-1/2)
<Fracture toughness. KIC>
→ All KIC of samples was identical
→ No siginificance
Comparison p-value
P1Zn2.5 vs P1.5Zn3 0.758
P1Zn2.5 vs P1.25Zn2 0.066
P1.25Zn2 vs P1.5Zn3 0.109
2/12/1 dY
Kc
Y
K ICICf
4㎛
12.1Y
Composition KIC
Crystalline phase size (㎛)
P1.5Zn3 2.29±0.34 0.361
P1.25Zn2.75 - 0.962
P1.25Zn2 2.07±0.3 1.026
P1Zn2.5 2.34±0.11 3.878
12.1
ICKslope
Composition KIC Slope
P1.5Zn3 2.29±0.34 1.15
P1.25Zn2 2.07±0.3 1.04
P1Zn2.5 2.34±0.11 1.18
Hall-Petch relation + Griffiths eq.
P1Zn2.5 P1.25Zn2 P1.5Zn3
sizeGrain Crack
Assumption)
Fracture toughness
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
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26/14
0 500 1000 1500 2000 2500150
200
250
300
350
400
450
500-- 4.00 1.00 0.44 0.25 0.16
P1.5Zn3
P1.25Zn2.75
P1.25Zn2
P1Zn2.5
(Crystalline phase width)-1/2
,d-1/2
(m-1/2
)
Crystalline phase width, d (μm)
Fra
ctu
re s
tre
ng
th,
f (M
Pa) <Width>
• The calculated slope from the crystalline phase size signified
the relevance with KIC showed very low value compared to
the measurement → (P1Zn2.5 : 0.382 vs 1.18)
• This is explained that the crystalline phase size is too
small(<4㎛), hence the only Hall-Petch corresponded.
• Fracture strength increased as decrease of crystalline
phase size (length, width) until critical point and it showed
the deviation and decrease. It could be attributed to the
presence of secondary phase cristobalite (SiO2).
2/1 dkyyf
Slope : 0.112
12.1
ICKslope
Composition KIC
Slope (Calculated)
Slope (Measured)
P1Zn2.5 2.34±0.11 1.18 0.382
2/12/1 dY
Kc
Y
K ICICf
Hall-Petch relation + Griffiths eq. <Length>
0 500 1000 1500 2000150
200
250
300
350
400
450
500-- 4.00 1.00 0.44 0.25
P1.5Zn3
P1.25Zn2.75
P1.25Zn2
P1Zn2.5
Crystalline phase length, d (μm)
Fra
ctu
re s
tre
ng
th,
f (M
Pa
)
(Crystalline phase length)-1/2
,d-1/2
(m-1/2
)
length
width
Slope : 0.382
sizeGrain Crack
Assumption)
Srength vs Crystalline phase size
Seoul National UniversityDepartment of Material Science & EngineeringElectronic Materials & Devices Laboratory
27/40
0 500 1000 1500 2000 25004
5
6
7-- 4.00 1.00 0.44 0.25 0.16
(Crystalline phase width)-1/2
,d-1/2
(m-1/2
)
Vic
ker's h
ard
ne
ss (
GP
a)
Crystalline phase width, d (μm)
P1.5Zn3
P1.25Zn2.75
P1.25Zn2
P1Zn2.5
27/14
2/1
0
dkHH h
• Vickers hardness increased as decrease of crystalline phase
size (length, width).
• Even though fracture strength did not followed the Hall-
Petch relation, the hardness coincided with it.
0 500 1000 1500 2000 25004
5
6
7-- 4.00 1.00 0.44 0.25 0.16
P1.5Zn3
P1.25Zn2.75
P1.25Zn2
P1Zn2.5
Crystalline phase legnth, d (μm)
Vic
ker's h
ard
ne
ss (
GP
a)
(Crystalline phase length)-1/2
,d-1/2
(m-1/2
)
7741.0:
84.4:
4-9.27E:
2
0
R
H
kh
length
width
5402.0:
78.4:
4-6.03E:
2
0
R
H
kh
Hardness vs Crystalline phase size
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- Composition)
1) The nucleation agent P2O5 promoted nucleation, therefore, crystalline phase became small.
2) As increase of P2O5 and ZnO, secondary phase cristobalite peak intensity increased.
Why? : The Li+ ion was consumed to form Li3PO4 crystal which promoted the LS2 growth, and to
maintain the neutrality in Zn2+ tetrahedron.
- Crystallization) The crystalline phase grew as increase of crystal growth temperature and time.
Does the strength and hardness of crystalline phase of Lithium disilicate glass-ceramics
follows the Hall-Petch relation?
- Fracture strength : No. It showed scattering and decrease and deviation at critical point.
Why? : It is assumed that the secondary phase cristobalite(SiO2) could affected fracture strength.
- Hardness : Yes. It followed the Hall-Petch relation.
Why? : It will be studied further in future work.
Effect of crystallization on mechanical properties of lithium disilicate glass-ceramics
Surmmary
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II. Effect of the colorants on the color and
translucency of lithium disilicate glass-
ceramics
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• Lambert’s law : 흡광도는 cell의 길이에 비례 A=ab, a=constant, “absorptivity” [L/g cm or L/mole cm]
• Beer’s law : 흡광도는 시료의 농도에 비례 A=a`c, c=concentration [g/L, mole/L]
• Lambert-Beer’s law = A=abc
Optical density (Absorbance)
0
0
log=log=
100×=%
P
PTAbsorbance
P
PT
-
Principles of colour
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Absorption by
transition metal
d block
3d orbitals filling
3d, 4f metal ion이 light을 선택적으로 흡수(보색이 반사되어 색으로 나타남)
Metal 이기 때문에 emission이 아님.
Metal 이온이 LS2 crystalline phase 혹은 이차상(Cristobalite, quartz, LS, LP), 유리상에 위치(확실한 위치는 알 수 없음 분석필요)Fig. 6. Band diagram of a typical metal (A)
showing light absorption transitions in
Absorption of light
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33/22Ref) https://scilearn.sydney.edu.au/fychemistry/calculators/colour_wheel.shtml
Complimentary colour
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<Redox in soda lime glass>
+4+3+3+4 Sb+CeSb+Ce →Yellow Weak yellow
Ce4+ Ce3+
Cr2O3-Mn2O3-CeO2-V2O5-CuO-As2O3-Sb2O3-Fe2O3
Ref) Chemical approach to Glass, Milos Bohuslav Volf
High oxidation potential
<Redox potential series in soda lime glass>
Factors of color generation in glass
• Type and concentration of polyvalent ions
• Redox state of glass
• Oxygen pressure and so on http://artglassdesigns.blogspot.kr/2014/12/colored-glass.html
<Colors generated by colorants in soda lime glass>
Ref) Fundamentals of Inorganic Glasses, Arun K. Varshneya
Color generation in glass
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Ref) http://www.konicaminolta.com/instruments/knowledge/color/part3/02.html
Usually, a person looks at the color of the object and ignores the
specular reflection of the light source. SCE mode would be
sufficient to express colour
Brightness, lightness, luminance, or value, which describes the intensity of the colour, the
number of photons reaching the eye.
SCE (Specular Component Excluded)
SCI (Specular Component Included)
L* (Lightness )
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Reference
Sample
Mask
Mask
• Shimadzu UV-2600
• Integrating sphere for diffuse reflectance
• 240~1400nm
DR
SR
When the specular reflectance is measured,
the samples locates in SR position which is
tilted 8 degree.
Uv-vis spectrometer
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400 500 600 7000
20
40
60
80
100
Diffu
sed r
eflecta
nce (
%)
Wavelength (nm)
V2O5 0
V2O5 0.05
V2O5 0.1
V2O5 0.25
V2O5 0.5
400 500 600 7000
20
40
60
80
100
Diffu
sed r
eflecta
nce (
%)
Wavelength (nm)
MnO2 0
MnO2 0.05
MnO2 0.1
MnO2 0.25
MnO2 0.5
V2O5 (mol%)
L* a* b*
0 69.7 -1.3 -2.4
0.05 67.5 -3.7 3.3
0.1 63.5 -4.7 6.9
0.25 53.3 -5.1 17
0.5 42.5 0.4 21.9
MnO2 (mol%)
L* a* b*
0 69.7 -1.3 -2.4
0.05 71.8 -0.9 -2.8
0.1 70.5 -0.6 -2.4
0.25 69.2 0.2 1.8
0.5 64.1 1.6 -0.7
400 500 600 7000
20
40
60
80
100
Diffu
sed r
eflecta
nce (
%)
Wavelength (nm)
MnO2 0
MnO2 0.05
MnO2 0.1
MnO2 0.25
MnO2 0.5
MnO2 1
MnO2 (mol%)
L* a* b*
0 67.5 -3.7 3.3
0.05 66.7 -3.4 3.6
0.1 63.5 -3.1 3.9
0.25 63.5 -2.1 6.3
0.5 57.5 -0.6 9.2
1 47.3 0.2 16.9
-6 -4 -2 0 2 4 6-5
0
5
10
15
20
25
0.5
0.25
0.1
0.05
0
1
0.5
0.25
0.10.05
1
0.5
0.25
0.1
V2O5 0~0.5 mol%
MnO2 0~1 mol%
V2O5 0.05 + MnO2 0~1 mol%
b*
a*
0.05
0.0 0.2 0.4 0.6 0.8 1.040
60
80
100
V2O5
MnO2
V2O5 0.05 + MnO2
Lig
htn
ess (
L*)
Amount of additives (mol%)
+V2O5 0.05mol%
4
3
2
1
0
A4
A3
A2
A3.5
A1
A4
A3.5
A3
A1
A2
HT
LT
MO
Diffused reflectance, L*a*b*
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300 400 500 600 700 8000
20
40
60
80
100
Tra
nsm
itta
nce (
%)
Wavelength (nm)
V2O5 0
V2O5 0.05
V2O5 0.1
V2O5 0.25
V2O5 0.5
300 400 500 600 700 8000
20
40
60
80
100
Tra
nsm
itta
nce
(%
)
Wavelength (nm)
MnO2 0
MnO2 0.05
MnO2 0.1
MnO2 0.25
MnO2 0.5
300 400 500 600 700 8000
20
40
60
80
100
Tra
nsm
itta
nce
(%
)
Wavelength (nm)
MnO2 0
MnO2 0.05
MnO2 0.1
MnO2 0.25
MnO2 0.5
300 400 500 600 700 8000
1
2
3
4
5
Ab
s.
Wavelength (nm)
V2O
5 (mol%)
0
0.05
0.1
0.25
0.5
300 400 500 600 700 8000
1
2
3
4
5
Ab
s.
Wavelength (nm)
MnO2 (mol%)
0
0.05
0.1
0.25
0.5
300 400 500 600 700 8000
1
2
3
4
5
Abs.
Wavelength (nm)
MnO2 (mol%)
0
0.05
0.1
0.25
0.5
T%, Abs.
+V2O5 0.05mol%
V5+V3+
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39/22
UV–Vismeasurementswere obtained in the
transmission mode in the
range from 200–1200 nm. The spectra were
converted into absorbance
and normalized to the sample thickness (optical
density in cm−1).
Literature survey
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500 600 700 800 900
678.3
663.3
642.5
Temperature (oC)
15K/min
20K/min
10K/min
5K/min
Endo
Exo
615.3
41500 600 700 800 900 1000
740.4
812.5
788.2
20K/min
15K/min
10K/min
5K/min
Temperature (oC)
Endo
Exo
740.4
500 600 700 800 900 1000
732.2
809.6
782.6
Temperature (oC)
20K/min
15K/min
10K/min
5K/min
Endo
Exo
732.2
500 600 700 800 900
676.6
662.2
643.3
Temperature (oC)
En
do
Exo
15K/min
10K/min
5K/min
20K/min
615.4
500 600 700 800 900
577
613.9
591.9
Temperature (oC)
5K/min
10K/min
15K/min
20K/min
E
nd
oE
xo
577
#1
#7 #8
#12 #13
500 600 700 800 900
694
677
656
Temperature (oC)
15K/min
20K/min
10K/min
5K/min
En
do
Exo
625.8
500 600 700 800 900
697.7
721.9
712.4
727.2
632.3
620.9
605.7
Temperature (oC)
5K/min
10K/min
15K/min
20K/min
E
nd
oE
xo
583.7
500 600 700 800 900
742.8
734.3
725.7
716.9
617
613.9
577.1
591.8
Temperature (oC)
20K/min
15K/min
10K/min
5K/min
En
do
Exo
500 600 700 800 900
Temperature (oC)
775.2
765.4
752
730.7693
707
718
727
640.6
627.9
61515K/min
20K/min
10K/min
5K/min
En
do
Exo
589.5
Discussion : Differential Scanning Calorimeter
#2 #3
#6
FE-SEM EDS Mapping
ElementWeight%
Atomic%
실투입(mol%)
O K 17.13 68.98
Si K 11.38 26.10
P K 0.53 1.09
K K 1.28 2.11
Ti K 0.15 0.20
V K 0.34 0.43
Zn L 0.88 0.86
Ce L 0.52 0.24
Totals 32.18
분석처 : KICET JEOL 6701F
Sample : 1) CeO2 0.5 TiO2 0.5 V2O5 0.5 (HF Etching X)
EDS resolution 작음 point로 찍으면 다른 부분까지 나옴
TEM (FIB) : Base(#12), CeO2 0.5 V2O5 0.5
43/22
분석처 : 가천대 Tecnai G2 F30 (300kV)
FIB : 가천대 나노기술혁신센터 FIB-STEM FEI Nova 200
Base : #12 기본 조성 (no colorant)
Hydro carbon damages
Ga 오염? 까만점들 (out focusing)
Cleaning 문제?
결정 터짐 carbon coaring 필요(터지는 시간 줄임) 회색빛 정도
FE-SEM EDS Mapping
• 5kV에서 Aperture Size 가 120 μm 경우 damage 발생 EDS Mapping 중 damage 발생 가능• KICET JEOL 6701F 에서는 15kV 15 current 맞춰도 damage 발생 X
Fundamentals of inorganic glasses, A. K. Varshneya , Physical ceramics, Yet-Ming Chaing, Dunbar Birnie III, W. David Kingery, (p437-)
m
x
x
x
TRT
TH
aN
fRTU
RT
G
a
DU
RT
EaD
RT
G
RT
EaUvva
RT
GEv
RT
Ev
f
2
0
2
0
0
exp13
exp1
exp
exp1exp)21(
)(exp2
exp1
Wilson-Frenkel theory
aN
RTD
3
Stokes-Einstein relation between the
diffusion coefficient and the viscosity
Crystal growth rate
According to Turnbull(1960) : reaction-rate theory, • υ frequency with which atoms are transported across the interface
• a0 : distance the crystal advances for a layer of attached molecules
• ΔGx : free energy of crystallization
0
f0
aU
TRT
THaU
m
ΔGm<<RT, Small undercooling
ΔGm>>RT Large undercooling
Crystal growth velocity is ~ 105cm/sec
과냉각이 작을 때 성장율은 ΔH, ΔT에 비례!
과냉각이 클 때는 한계값 도달! (점도가 높아짐)
ΔE’
ΔGx
ΔE’+ΔGx
Glass-Ceramics, P. W. Mcmillan 2nd edition
1) The irregular glass structure can be re-arranged into the
periodic lattice of the growing crystal
2) Energy released in the phase transformation process can
be eliminated by the heat flow away from the crystal-glass
interface
RT
G
RT
EaU xexp1exp0
a0 : interatomic seperation
υ : vibrational frequency at the crystal-glass interface
Bulk free energy of
crystallization
Energy barrier i.e.
activation energy
2
0
2
0
3
exp
aN
RTD
kT
EaD
0
2
0
2
0
3exp1
exp13
Na
fR
kT
GT
UU
RT
G
aN
fRTU
x
R
x
RT
EUU
RT
E
a
fDU
RT
EDD
kT
G
a
fDU
u
xu
exp
exp
exp
exp1
0
0
0
0
0
Negligibly small
compared with Du
Matusita
J. Mat. Sci, 10
(1975) 961
Vogel
Crystal growth rate
Reduced growth rate UR