Nano Structured Composite Materials for Thermoelectric Applications - - PowerPoint PPT Presentation
Nano Structured Composite Materials for Thermoelectric Applications Sung Jin Kim Sung-Jin Kim Ewha Womans University Department of Chemistry and Nano Science Department of Chemistry and Nano Science April 5, 2010 Thermoelectricity
April 5, 2010
연구분야
온도차에 의해 기전력이 발생하는 현상(Seebeck 효과) 또는 전류에 의해 열이 흡수,발생이 생기는 현상 (Peltier효과)
응용분야 응용분야
열전냉각 (Thermoelectric cooling) 열전발전 (Power generation)
NAS NAS A
2 www.spaceref.com/news/viewpr.html?pid=18796
HEAT IN
therm oelem ent electrical conductor
+
conductor electrical insulator
p
n p n
p
n
p
n
+
−
HEAT OUT
Laser Cooling Modules
El t i l d ti it ( ) i t ti
Figure of Merit : ZT
S
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κ = κ + κ
tot
Hi h l t i l d ti it
κ = κe + κph K
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K
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Difficulties in increasing ZT in bulk m aterials : T ators tals S ↑ ↔ σ ↓ σ ↑ ↔ S ↓ and k ↑ ZT
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I nsul Met
Sem iconductor
5
↑ ↓ ↑
10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
Carrier Concentration
10 10 10 10 10
m = effective mass τ = scattering time
r = scattering parameter klatt = lattice thermal conductivity T = temperature T = temperature γ = band degeneracy
Narrow band-gap semiconductors : Single carrier systems Heavy elements : High μ, low κ Large unit cell, complex structure : low κ Highly anisotropic or highly symmetric Highly anisotropic or highly symmetric Complex compositions : low κ, complex electronic structure Mass Fluctuation : low κ Hi h d it f t t th F i l l hi h S b k High density of states near the Fermi level : high Seebeck coefficient
Science, 303, 818
conductivity can be significantly reduced by the scattering of
I nterfaces that Scatter
Phonons Electrons conductivity can be significantly reduced by the scattering of unw anted heat flow at the interfaces
Scatter Phonons but not Electrons
Mean Free Path Λ = 10-100 nm Λ = 1-10 nm Wavelength λ = 10-50 nm λ = 1 nm
m ay be dram atically m odified due to the electron confinem ent in nanostructures w hich exhibit low - confinem ent in nanostructures w hich exhibit low dim ensional behaviors.
Nature 4 1 3 , 5 9 7 ( 2 0 0 1 ) Science 2 9 7 , 2 2 2 9 ( 2 0 0 2 ) Science 3 0 3 , 8 1 8 ( 2 0 0 4 )
Ag-Sb– rich
Majum dar, Science 3 0 3 , 7 7 7 ( 2 0 0 4 ) PbSeTe/ PbTe QD Super-lattices
AgPb1 8SbTe 2 0 ZT = 2 .2 @ 8 0 0 K
3.5 3.0 2.5 0K
Super lattices
8 0 0 K
Science 3 2 1 , 5 5 4 ( 2 0 0 8 ) N t i l
2.0 1.5 1.0
(ZT)300 Bulk m aterials Nano m aterials Year
1970 1980 1990 2000 2010 1950 1960 0.0 1950 1960 0.5
Tl0 .0 2Pb0 .9 8Te ZT = 1 .5 @ 7 7 3 K
Science 3 2 0 , 6 3 4 ( 2 0 0 8 ) Nature 4 5 1 1 6 8 ( 2 0 0 8 ) Bulk m aterials
Sb– rich
Nature 4 5 1 , 1 6 8 ( 2 0 0 8 ) Nature 4 5 9 ( 2 0 0 9 )
BixSb 2 -xTe 3 Nanocom posite I n 4Se 3 ZT = 1 .5 @ 7 0 0 K
Nanodot Nanocom posites Nanograined Nanocom posites
2.5 2.5 1.8 1.8
1.8 1.8 1.5
Electron m ean free path Woochul Kim, Yunsei Univ.
Nanoparticles Embedded in Bulk Thermoelectric Materials
Electron Phonon
nanorod nanoparticles Coherent interface (Matrix/nanoparticl es) nanoparticles Matrix Matrix + nanorod, nanoparticles
Type of Bull Matrixes Nanoparticles Nanorods Bi2Te3 PbTe Bi2Te3 In2Te3 Bi2Te3 Bi2Se3 Sb2Te3 BixSb2 xTe3 Bi2Te3 CdSe Te
2 3 x 2-x 3
Bi
Bi( C2H 3O2) 3 ( or Sb( C2H 3O2) 3) +
1 -Dodecanthiol Oleylam ine, 1 -Octadecene
75oC 80oC
Size Control
+ Te-TOP ( or Se-TOP)
Various reaction temperature
85oC 90oC
M h l C t l
Various Source
Morphology Control
Bi2Se3 Composition
1 4 0 oC
Control
1 0 0 oC
Bi Bi Te
Bi0 9(3)Sb0 9(2)Te3 Bi1 5(3)Sb0 5(1)Te3 Bi1 9(3)Sb0 1(1)Te3
1 1
Bi Bi2Te3
0.9(3)Sb0.9(2) e3
Bi1.5(3)Sb0.5(1)Te3 Bi1.9(3)Sb0.1(1)Te3
Sample Preparation
Nanocomposite ingot sawing Polishing (400 – 2000 - micro) Rocking furnace
800 900
Data Analysis Measurements
300 400 500 600 700 800 200 300 400 500 600 700
Seebeck Coefficient & Electrical conductivity measurement
Temperature(K)
300 400 500 600 700 800 4 5 6 7
conductivity measurement
Nanocomposite sample
Temperature(K)
300 400 500 600 700 800 1 2 3
Thermal conductivity measurement
Nano-structured Bulk Therm oelectirc Material
PbTe ingot with Bi2Te3 nanoparticle
+
Bi2Te3 nanoparticles(~150nm) PbTe incoherent interface
Materials Lattice parameter Structure Lattice mismatch
PbTe 6.3462A Rock salt
PbTe with Bi2Te3
30% (a/a) Bi2Te3 a=4.385A, c=30.48A Rhomboh edral 2 3
ingot
PbTe ingot with Bi2Se3 nanoparticle
+
PbTe + Bi2Se3
+
Coherent(stress) Bi2Se3 nanoparticles(~80nm) PbTe i h t i t f Coherent(stress) incoherent interface
In2Te3 ingot with Bi2Te3 nanoparticle
+
coherent interface (Particle size < 20nm)
In2Te3 Matrix
Bi2Te3 nanoparticles (~150nm) (~150nm)
In2Te3 ingot with Bi2Se3 nanoparticle
+
coherent interface
1 5
Bi2Se3 nanoparticles (~80nm)
In2Te3 Matrix
Composition dependent of electrical properties PbTe + 2.7% Bi2Te3 PbTe + 10% Bi2Te3 PbTe + 20% Bi2Te3
Seebeck Coefficient (μV/K) Power Factor (μW/cmK2) Electrical Conductivity (S/cm)
60
K)
10 2) 1200
m)
2 3
PbTe + 2.7% bulk Bi2Te3
fficient (μV/K
6 8
2 600 800 1000
uctivity (S/cm
ebeck Coef
2 4
Power Facto
200 400 600
trical Condu
250 300 350 400 450 500 550 600 650 700
See Temperature (K)
250 300 350 400 450 500 550 600 650 700
P Temperature (K)
300 350 400 450 500 550 600 650 700
Elect Temperature (K)
The values : Negative value The values : ~1000 S/cm at R.T. Majority of charge carriers : Electrons The values : ~ -60~-220μV/K 1.5 ~9 W/cmK2 The values : 60 220μV/K
Power Factor increase with decreasing nanoparticle content
tensity
Bulk Bi2Te3
* ** * ative int
20 30 40 50 60 70 80
* * * 2 θ Rela sity
Nanoparticle Bi2Te3
ve intens
20 30 40 5 6 70 80
Relativ
20 30 40 5 6 70 80
2 θ
1 Remove 2 Electrochemically deposition
barrier oxide layer
Bi nanowire material
Te nanowire material
AAO template AAO template
1 Remove 2 Electrochemically deposition
barrier oxide layer
nanowire material 2 Remove 1 Remove
AAO template
Ag film
structure (b) one element or binary nanowire arrays by pulsed potential structure (b) one element or binary nanowire arrays by pulsed-potential deposition into porous anodic alumina template
열전재료용 나노입자, 나노선 제조 Bulk에 나노입자, 나노선 삽입 Hydrothermal법을 이용한 Bi2Te3의 morphologies PbTe ingot with Bi2Te3 Colloidal법을 이용한 Bi2Te3 나노입자 Bi2Se3나노입자 PbTe ingot with Bi2Se3 Sb2Te3 나노입자 BixSb2 xTe3 나노입자 PbTe ingot with Bi2Se3 BixSb2-xTe3 나노입자 Bi 나노입자 InTe ingot with Bi2Se3 CdSe 나노선 전기화학법을 이용한 Bi, Te 나노선 InTe ingot with Bi2Te3
Nanostructured bulk CompositeTE materials
nanostructuring nanostructuring
the nanocomponent in bulk TE materials the nanocomponent in bulk TE materials
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Ha Yeong Kim Jieun Park, Hee Jin Kim
Grant: 2 1 st Century Frontier R&D Program s NRF,
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