Sympozjum Wydziału Fizyki 17 kwietnia 2008 Transport ładunku elektrycznego w amorficznych,...
If you can't read please download the document
Sympozjum Wydziału Fizyki 17 kwietnia 2008 Transport ładunku elektrycznego w amorficznych, nanokrystalicznych i kompozytowych przewodnikach elektronowych
Sympozjum Wydziau Fizyki 17 kwietnia 2008 Transport adunku
elektrycznego w amorficznych, nanokrystalicznych i kompozytowych
przewodnikach elektronowych i jonowych Jerzy E.Garbarczyk, Wojciech
Wrbel Zakad Joniki Ciaa Staego Wydzia Fizyki PW
Slide 2
Motywacja Cel poznawczy Badanie transportu adunku elektrycznego
w mao poznanych formach fazy skondensowanej Cel aplikacyjny
Zastosowania w urzdzeniach do konwersji i magazynowania energii
(baterie litowo-jonowe, ogniwa paliwowe, sensory gazowe,
superkondensatory) Sympozjum Wydziau Fizyki 17 kwietnia 2008
Slide 3
Prezentacje Jerzy E.Garbarczyk Nowe nanomateriay i kompozyty
oparte na szklistych przewodnikach elektronowych i jonowych
Wojciech Wrbel Korelacja midzy elektrycznymi i mechanicznymi
waciwociami cieczy szkotwrczych Sympozjum Wydziau Fizyki 17
kwietnia 2008
Slide 4
Novel nanomaterials and composites based on electronic and
ionic conductive glasses
Slide 5
Outline Advantages and disadvantages of ionic and electronic
conductive glasses Novel nanomaterials based on
lithium-vanadate-phosphate (LVP) glasses Novel nanomaterials based
on lithium-iron-phosphate (LFP) glasses Novel composites based on
ionically conductive glasses Summary
Slide 6
Advantages and disadvantages of conductive glasses Advantages
simple processing possibility of forming various shapes isotropy
and homogeneity absence of grain boundaries high ionic conductivity
at room temperature (up to 10 -2 S/cm for AgI based conducting
glasses) high electronic conductivity at above 300C (up to 10 -3
S/cm for vanadia rich glasses) inherent ability to
nanocrystallization (this study) possibility of considerable
modification of the composition and electrical properties
Slide 7
Example: vanadia-based glasses V 2 O 5 main glass former,
source of electronic conduction via V 4+ V 5+ hopping of small
polarons P 2 O 5 supporting glass former Li 2 O glass modifier,
source of mobile Li + ions Ag 2 O glass modifier, source of mobile
Ag + ions AgI dopant, main source of mobile Ag + ions Mixed
ionic-electronic conductivity in systems: Li 2 O - V 2 O 5 - P 2 O
5 (Li + /e - ) AgI - Ag 2 O - V 2 O 5 - P 2 O 5 (Ag + /e - )
Slide 8
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 9
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 10
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 11
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 12
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 13
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 14
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses or
Slide 15
Model of the electrical charge transport in Li 2 O-V 2 O 5 -P 2
O 5 glasses
Slide 16
or
Slide 17
Isotherms of the total electrical conductivity in Li 2 O-V 2 O
5 -P 2 O 5 glasses V 2 O 5 -rich glasses ionic electronic mixed
P.Jozwiak, J.Garbarczyk, Solid State Ionics 176 (2005) 2163
H.Takahashi, T.Karasawa, T.Sakuma, J.E.Garbarczyk, ICPSSI-2,
Yokohama, 2007
Slide 18
Total electrical conductivity at 100C vs. composition in AgI-Ag
2 O-V 2 O 5 -P 2 O 5 glasses J.E.Garbarczyk, P.Machowski et al.
Mol.Phys.Rep. 35 (2003) 139. electronic ionic
Slide 19
Total electrical conductivity at 100C vs. composition in AgI-Ag
2 O-V 2 O 5 -P 2 O 5 glasses electronic ionic electronic ionic
J.E.Garbarczyk, P.Machowski et al. Mol.Phys.Rep. 35 (2003)
139.
Slide 20
Advantages and disadvantages of conductive glasses (cont.)
Disadvantages metastability composition and structure less known
than those of the crystalline materials low glass transition
temperature of the best ion conductive glasses (for AgI-doped
glasses 60C < T g < 100C) low fracture toughness moderate
electronic conductivity at 20C of glassy cathode materials
Slide 21
Aims of our studies preparation of new nanomaterials derived
from conductive glasses exhibiting better electrical properties and
thermal stability than the initial glasses preparation of new
glassy-crystalline composites exhibiting improved mechanical
properties compared to the glasses
Slide 22
Novel nanomaterials based on lithium-vanadate-phosphate (LVP)
glasses It is known that nanostructured materials exhibit
attractive properties, often dramatically different than those of
the crystalline or amorphous counterparts. Effect of
nanocrystallization on ionic conductivity St. Adams, K.Hariharan,
J.Maier, Solid State Ionics 86-88 (1996) 503. AgI-rich glasses of
the system AgI-Ag 2 O-M x O y Effect of nanocrystallization on
electronic and mixed conductivity J.E.Garbarczyk, P.Jozwiak et al.
Solid State Ionics 175 (2004) 691. V 2 O 5 -rich glasses of the
system Li 2 O-V 2 O 5 -P 2 O 5 a) 15Li 2 O70V 2 O 5 15P 2 O 5 b)
90V 2 O 5 10P 2 O 5
Slide 23
DSC Nanocrystallization of the 90V 2 O 5 10P 2 O 5 glass
Slide 24
SEM picture of a 90V 2 O 5 10P 2 O 5 sample after
nanocrystallization at T c 340C
Slide 25
20 nm visible nanocrystallites of V 2 O 5 covered by a glassy
phase
Slide 26
SEM picture and XRD pattern of a 90V 2 O 5 10P 2 O 5 sample
after massive crystallization at 540C - orthorhombic V 2 O 5
Slide 27
SEM picture of a 90V 2 O 5 10P 2 O 5 sample after massive
crystallization at 540 o C (another fragment) orthorhombic V 2 O 5
crystallites
Slide 28
Discussion of the results on vanadia-based nanomaterials Mott
theory of electron hopping in disordered systems R average distance
between hopping centers C fraction of hopping sites occupied by
electrons N concentration of hopping centres inverse localization
length of the electron wave function r p radius of a small polaron
for T > / 2 Debye temperature
Slide 29
Discussion of the results on vanadia-based nanomaterials
Samples after nanocrystallization V2O5V2O5 20 nm
Slide 30
Discussion of the results on vanadia-based nanomaterials
Samples after nanocrystallization V2O5V2O5 20 nm higher
concentration of V 4+ -V +5 pairs
Slide 31
Discussion of the results on vanadia-based nanomaterials
Samples after nanocrystallization Easy conduction paths interface
regions between nanocrystallites and glassy phase. Higher
concentration of V 4+ -V 5+ pairs in these regions than inside
grains. V2O5V2O5 20 nm high concentration of V 4+ -V +5 pairs easy
conduction path +
Slide 32
Discussion of the results (cont.) Sample after massive
crystallization There is no intermediate glassy phase. The
electrical transport between grains is partly blocked by the
presence of grain boundaries.
Slide 33
Novel nanomaterials based on lithium-iron-phosphate (LFP)
glasses Crystalline lithium-iron-phosphates (olivines)
Nanocrystallization of glassy samples - SEM Cooperation with Prof.
Christian Julien, Univ. P.et M.Curie, Paris, France (local
structure) A.Ait Salah, P.Jozwiak, J.Garbarczyk, Ch.Julien et al.
Journal of Power Sources 140 (2005) 370.
Slide 34
Zwizki interkalowane - przykady Oliwiny i zwizki pokrewne
Slide 35
Crystalline lithium-iron-phosphates Crystalline olivine-type
phases - LiFePO 4 and FePO 4 as well as Li x FePO 4 solid solutions
- are under intensive studies worldwide as the most competitive
cathode materials for Li-ion rechargeable batteries. These cathode
materials are: highly stable (thermally and electrochemically),
inexpensive, environment friendly. Furthermore they exhibit: high
specific capacity (170 mAh/g), high discharge voltage (3.5 V vs.
Li).
Slide 36
Crystalline lithium-iron-phosphates Crystalline olivine-type
phases - LiFePO 4 and FePO 4 as well as Li x FePO 4 solid solutions
- are under intensive studies worldwide as the most competitive
cathode materials for Li-ion rechargeable batteries. These cathode
materials are: highly stable (thermally and electrochemically),
inexpensive, environment friendly. Furthermore they exhibit: high
specific capacity (170 mAh/g), high discharge voltage (3.5 V vs.
Li). Unfortunately they have one serious deficiency very low
electrical conductivity - ca. 10 -10 Scm 1 at 25C.
Slide 37
Crystalline olivines (cont.) Many efforts have been undertaken
to improve their electrical properties by: introduction of carbon
additives, doping with supervalent cations, various synthesis
routes. Our alternative approach nanocrystallization of glassy
analogs of olivines: step 1:preparation of vitreous analogs of
these materials, step 2: turning these glasses into nanomaterials
by an appropriate thermal treatment.
Slide 38
Electrical properties after partial nanocrystallization (sample
of x = 0)
Slide 39
SEM picture after partial nanocrystallization for sample of x =
0
Slide 40
Electrical properties after partial nanocrystallization (sample
of x = 0.4) t (530C)=1.110 -2 S/cm t (50C)= 1.810 -8 S/cm t
(50C)=7.610 -8 S/cm 4 times
Slide 41
SEM micrograph after crystallization for sample of x = 0.4
Slide 42
Slide 43
Novel composites based on ionically conductive glasses
Motivation Ag + - ion conductive glasses exhibit high electrical
conductivity (up to 10 -2 Scm -1 at 25C), but some of their
mechanical properties may cause problems with samples machining
(e.g. cutting and polishing) and limit eventual prospective
applications. In order to minimize this drawback we propose new
composites based on silver-ion conductive glasses.
Slide 44
Novel composites based on ionically conductive glasses (cont.)
Glassy components: AgI-Ag 2 O-B 2 O 3 AgI-Ag 2 O-P 2 O 5 AgI-Ag 2
O-V 2 O 5 Ceramic powder components: Diamond (1-2 m) -Al 2 O 3 (2
m) ZrO 2 (1 and/or 10 m) Composites prepared in 50 - 50 % vol
fractions B 2 O 3, P 2 O 5, V 2 O 5 glass formers Ag 2 O glass
modifier AgI dopant
Slide 45
High-pressure route of preparation of the composites Facility
at the Institute of High Pressure Physics, Polish Academy of
Sciences, Warsaw
Slide 46
High-pressure route of preparation of the composites (cont.)
100-200C 100-250C 3-8 GPa
Slide 47
SEM and XRD studies Obrazek SEM (fosforanowe z diamentem,
boranowe z alumina) Glass: 40AgI30Ag 2 O30P 2 O 5 Diamond powder
(1-2 m) Synthesis: p = 3 GPa, T = 250C as-prepared after annealing
at 200C M.Zgirski, J.Garbarczyk et al., Solid State Ionics, 176
(2005) 2141
Slide 48
SEM studies (cont.) 50AgI33Ag 2 O17B 2 O 3 : -Al 2 O 3 (2 m) -
a phase view Al 2 O 3 Glass
Slide 49
SEM studies (cont.) 55AgI30Ag 2 O15B 2 O 3 : ZrO 2 (1 m) - a
phase view ZrO 2
Slide 50
Electrical properties of composites above room temperature
40AgI30Ag 2 O30P 2 O 5 : diamond 200 =1.610 -2 Scm -1 27 =110 -4
Scm -1 E=0.34 eV E=0.54 eV TgTg glass
Slide 51
Electrical conductivity of composites at low temperatures
M.Foltyn, M.Wasiucionek, J.E.Garbarczyk et al.., Solid State
Ionics, 179 (2008) 38
Slide 52
Mechanical properties - Vickers microhardness
xAgI(100-x)(0.67Ag 2 O0.33B 2 O 3 ) composites (with -Al 2 O 3 )
glasses
Slide 53
Electrical properties of composites (cont.) Lower specific
conductivity of the composites can be compensated by a possibility
of preparing thinner samples. Mechanically sound membranes of ca
100 m thickness can be fabricated. sheet of paper - edge composite
1. (ca 100 m) composite 2. (ca 300 m)
Slide 54
Summary Conductive glasses can be promising starting materials
to prepare attractive composites and nanostructured materials. The
annealing of the V 2 O 5 rich glasses (LVP) to T c leads to their
nanocrystallization. The resulting nanomaterials exhibit much
higher electronic conductivity (10 -1 S/cm at 300C), lower
activation energy and better thermal stability than the initial
glasses.
Slide 55
Summary (cont.) Electrical properties of lithium-iron-phosphate
(LFP) glasses are similar to crystalline olivines. It was found
that thermal nanocrystallization of LFP glasses leads to the
conductivity enhancement,
Slide 56
Summary (cont.) Electrical properties of lithium-iron-phosphate
(LFP) glasses are similar to crystalline olivines. It was found
that thermal nanocrystallization of LFP glasses leads to the
conductivity enhancement,...therefore it seems to be a promising
way for electrical conductivity improvement of amorphous
lithium-iron-phosphates. A prospective high-pressure method was
used to produce silver ion conductive composites based on AgI doped
glasses with good electrical and mechanical properties.
Slide 57
Zesp badawczy Marek Wasiucionek Pawe Jwiak Jan L.Nowiski Marek
Foltyn Irena Gorzkowska Wydzia Chemiczny PW Bogdan Paosz Unipress
(IWC PAN) Stanisaw Gierlotka Unipress (IWC PAN)
Slide 58
R. Bacewicz, M. Wasiucionek, A. Twarg, J. Filipowicz, P. Jwiak,
J.E. Garbarczyk, J. Mat. Sci. 40 (2005) 4267-4270.
Slide 59
Electrical properties of composites above room temperature
40AgI40Ag 2 O20B 2 O 3 : -Al 2 O 3 M.Foltyn, M.Wasiucionek,
J.Garbarczyk et al. J.Power Sources 173 (2007) 795 =1.610 -2 =2.510
-3