Solid State Chemistry Meets Physcis: Thermoelectric Materials AN INTERDISCIPLINARY COLLABORATION KANATZIDIS MSU, CHEMISTRY Solid State Chemistry Synthesis, Discovery KANATZIDIS MSU, CHEMISTRY Solid State Chemistry Synthesis, Discovery Ctirad UHER Univ of Michigan Physics Ctirad UHER Univ of Michigan Physics TIM HOGAN MSU, E. ENGINEERING MEASUREMENTS S. D. MAHANTI MSU, PHYSICS Theory C. KANNEWURF Northwestern Univ E. Engineering H. Schock, T. Shih MSU, Mechanical Engineering Applications
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Solid State Chemistry Meets Physcis: Thermoelectric Materials
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Solid State Chemistry Meets Physcis: Thermoelectric Materials
Solid State Chemistry Meets Physcis: Thermoelectric Materials
AN INTERDISCIPLINARY COLLABORATION
KANATZIDISMSU, CHEMISTRY
Solid State ChemistrySynthesis, Discovery
KANATZIDISMSU, CHEMISTRY
Solid State ChemistrySynthesis, Discovery
Ctirad UHERUniv of Michigan
Physics
Ctirad UHERUniv of Michigan
Physics
TIM HOGANMSU, E. ENGINEERING
MEASUREMENTS
S. D. MAHANTIMSU, PHYSICS
Theory
C. KANNEWURFNorthwestern Univ
E. Engineering
H. Schock, T. ShihMSU, Mechanical
EngineeringApplications
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Michigan State University…Michigan State University…
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THERMOELECTRIC POWER(Seebeck Coefficient)
ΔV Smeasured= ΔVΔT
Smeasured= Ssample-SCu
ΔT
Cu block
Cu blockheater
constantan
sample
zero current technique:extremely useful probefor investigation ofintrinsic conduction in granular or polycrystallinematerials
Structure of Bi2Te3 and NaClStructure of Bi2Te3 and NaCl
xy
z
x
z
NaCl Bi2Te3 defect NaCl
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TYPICAL BEHAVIOR OF MATERIALS
S>50 µV/K
S>-50 µV/K
0<S<20 µV/K
-20 µV/K<S<0
T (K)
S (µV/K)S (µV/K)
T (K)
metal-likesemiconductor-like
p-type
n-type n-type
p-type
LARGE
SMALL
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Power Factor (S2*σ) vs Carrier Concentration
Power Factor (S2*σ) vs Carrier Concentration
Carrier Concentration, cm-1
1017 1018 1019 1020 1021
S2*σThermopower, Sconductivity
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Thermopower and Electronic Structure
• σ(E) is the electrical conductivity determined as a function of band filling or Fermi energy, EF. If the electronic scattering is independent of energy, σ(E)is just proportional to the density of states (DOS) at EF.
• For maximum S, a large asymmetry in the DOS and/or scattering within a few kTabove and below the Fermi energy is required.
Quenched and annealed β-K2Bi8Se13Quenched and annealed β-K2Bi8Se13
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Abs
orpt
ion
Energy, eV
after annealingquenched
Eg=0.59 eV
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CsBi4Te6CsBi4Te6
xy
z
C 2/m
51 Å
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“Undoped” as-prepared material“Undoped” as-prepared material
0
20
40
60
80
100
120
0
5
10
15
20
0 50 100 150 200 250 300
S (µ
V/K
) κ (W/m
-K)
Temperature (K)
DY72121
0
50
100
150
200
250
300
350
0 50 100 150 200 250 300
dy72121(CsBi4Te6 crystal)
Con
d. (S
/cm
)
Temperature (K)
conductivity thermopower
Thermal conductivity
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Crystals of CsBi4Te6Crystals of CsBi4Te6
1 mm1 mm
100 µm
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Doped CsBi4Te6Doped CsBi4Te6
0
1000
2000
3000
4000
5000
6000
7000
8000
0
50
100
150
200
0 50 100 150 200 250 300 350
SbI3 doped CsBi
4Te
6
Con
duct
ivity
(S/c
m) S
eebeck (µV/K
)
Temperature (K)
At 260 K: S ~174 µV/KCond. ~1400 S/cm
κ ~14 mW/cm-K
ZTmax
~0.8
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Thermal Conductivity of p-type CsBi4Te6
Thermal Conductivity of p-type CsBi4Te6
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0 50 100 150 200 250 300 350
κ (W
/m. K
)
Temperature (K)
parallel to needle
perpendicular to needle
Data by Uher et al
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Doping with SbI3Doping with SbI3
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CsBi4-xSbxTe6 x = 0.3
SbSbBiBi
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CsBi4Te6CsBi4Te6
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250 300 350
Figure of Merit (ZT)
CsBi4Te
6 doped
p-Bi2Te
3 Marlow
ZT
Temperature (K)
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Best TE MaterialsBest TE Materials
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000 1200 1400
n-BiSb �
n-SiGe sintered
CsBi4Te
6
LaFe3CoSb
12
Bi2Te
3
PbTe
ZT
Temperature (K)
RT
Temperature (K)
ZT
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ConclusionsConclusions
• The strategy to search for new materials in the (A2Q)n(PbQ)m(Bi2Q3)p (Q=Se, Te) system is successful
• Many new promising compounds identified• All compounds strongly anisotropic• Doping studies are important in ZT optimization• ZT for β-K2Bi8Se13 ~0.7 at rt, higher at >400K
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ReferencesReferences• “The Role of Solid State Chemistry In The Discovery of New
Thermoelectric Materials” Mercouri G. Kanatzidis, Semiconductors and Semimetals, 2000, 69, 51-100.
• Slack,G. A. “New Materials and Performance Limits for Thermoelectric Cooling” in CRC Handbook of Thermoelectrics" Edited by Rowe, D. M. CRC Press, Boca Raton, 1995, pp. 407-440
• Tritt T. M. "Thermoelectrics run hot and cold", Science. 1996, 272, 5266, 1276-1277.
• Mahan, G. D. “Good thermoelectrics” Solid State Phys: 1998, 51, 81-157. (c) DiSalvo, F. J. "Thermoelectric cooling and power generation", Science. 1999, 285 5428, 703-706
• Thermoelectric Materials 1998- The Next Generation Materials for Small-Scale Refridgeration and Power Generation Applications, edited by Tritt, T. M.; Kanatzidis, M. G.; Mahan, G. D.; Lyon, Jr., H. B. Mat. Res. Soc.Symp. Proc. 1999, Vol. 545, 233-246.
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CollaboratorsCollaborators
Prof. Tim Hogan, Dept of Electrical Engineering, MSUProf. S. D. (Bhanu) Mahanti, Dept. of Physics, MSUProf. Carl R. Kannewurf, Dept of Electrical Engineering, Northwestern Univ.Ctirad Uher, Dept. of Physics, U of MArt Schultz, Argonne NL
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TE Research groupTE Research group
• Dr Duck young Chung• Dr Antje Mrotzek• Dr Kuei fang Hsu• Lykourgos Iordanidis• Kyoung-shin Choi• Jun-Ho Kim• Sandrine Sportouch• Rhonda Patschke
• Tim McCarthy• Dr. Jun-Huan Do
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AcknowledgementsAcknowledgements• Dr. Antje Mrotzek• Lykourgos Iordanidis• J. A. Aitken• Jun-Ho Kim• Joseph Wachter• Marina Zhuravleva• Xuini Wu• Jim Salvador• Brad Sieve• R G Iyer• Dr. Theodora Kyratsi• Dr. J.-H. Do• Dr. Duck Young Chung• Dr. Servane Coste• Dr. Pantelis Trikalitis• Dr. Susan Latturner• Dr. Kuei-fang Hsu