Intrinsic Quasi 1-D Lattice Instability and ...

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Intrinsic Quasi 1-D Lattice Instability and Thermoelectricity in In 4 Se 3-δ 4 3 δ Jong-Soo Rhyee, C. Cho, K. H. Lee, S. M. Lee, S. I. Kim, J. H. Shim 1 , Y. S. Kwon 2 , and Gabriel Kotliar 3 Materials Research Center , Samsung Advanced Institute of Technology 1 Dept. of Chemistry, Pohang University of Science and Technology 2 Dept. of Physics, Sung Kyun Kwan University 3 Dept. of Physics and Astronomy , Rutgers University , USA

Transcript of Intrinsic Quasi 1-D Lattice Instability and ...

Page 1: Intrinsic Quasi 1-D Lattice Instability and ...

Intrinsic Quasi 1-D Lattice Instability and Thermoelectricity in In4Se3-δy 4 3 δ

Jong-Soo Rhyee, C. Cho, K. H. Lee, S. M. Lee, S. I. Kim, g y , , , , ,J. H. Shim1, Y. S. Kwon2, and Gabriel Kotliar3

Materials Research Center, Samsung Advanced Institute of Technology, g gy1Dept. of Chemistry, Pohang University of Science and Technology 2Dept. of Physics, Sung Kyun Kwan University 3Dept. of Physics and Astronomy, Rutgers University, USAp y y g y

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Low Thermal Conductivity and CDWLow Thermal Conductivity and CDW

Extremely low thermal conductivity

- 2-D layered WSe2 thin filmDi d d l d t t- Disordered layered structure

- κ=0.04 W/mK

* Limitations

Crystal structure of WSe2

C. Chritescue et al. Science (2007)

* Limitations- Thin film structure- Electrical insulator

Charge Density WaveCharge Density Wave (CDW)- Strong electron-phonon coupling

)(εψ k

Strong electron phonon coupling - Density wave energy gap- Low D Lattice instability

kVk2)0()0( '

a-2b

2

a+2b ∑≠ −

=kk kk

k EE

kVkE

'0'

0

)()0(

2'

2nd d t b ti th

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2a 2nd order perturbation theory

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Thermoelectric properties of CDWThermoelectric properties of CDW

Toy model – CeTe2

CeTe2

-High TCDW

Lattice-Lattice distortion along the plane of CDW

Crystal structure of CeTe2CeTe2 electron diffraction Te-layer distortion

K. Y. Shin et al. Phys. Rev. B (72) 85132 (2005)

Thermoelectricity in CeTe2

2

- Low thermal conductivity

L

-1

0

1

Ener

gy (e

V)

- Low Seebeck coefficient

-2 ΓX MΓ

Z

Th l d ti it (l ft) d S b k ffi i t f C T S

Energy band structure of CeTe2

J. S. Rhyee et al. J. Appl. Phys. (105) 53712 (2009)

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Thermal conductivity (left) and Seebeck coefficient of CeTe2-xSnx

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Peierls distortion and Thermoelectricity Peierls distortion and Thermoelectricity

Quasi-1D Bulk crystal

Quasi 1-D In chain in In4Se3 (100) plane

Y. B. Losovyj et al. Appl. Phys. Lett. (92) 122107 (2008)

O. A. Balitskii et al. Physica E (22) 921 (2004)

Crystal structure and TE properties of In4Se3-x

- Se-deficiency induced Peierls

ab-plane

bc-plane

induced Peierls distortion - Low thermal conductivity along the plane of Peierls

I S lJ. S. Rhyee et al. Nature ( )

plane of Peierls instability - High ZT (1.48 @705 K) for n-type materials

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In4Se3 crystal structure (2009)materials

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Peierls distortion and Thermoelectricity Peierls distortion and Thermoelectricity

Band structure and Peierls distortion

2

2

c d

0

1

En

ergy

(eV)

0

1

nerg

y (e

V)

-2

-1

E

X RUXSYTZΓ-2

-1

X RUXSYTZΓ

En

(c) In4Se3 and (d) In4Se2.75 band structureTEM and ED of In4Se2.78 along the ab- (a) and bc-planes (b).

- Quasi 1-D lattice distortion along the b-axis- Lattice doubling in electron diffraction and generalized electron susceptibility calculation

J. S. Rhyee et al. Nature (2009)APL (2009)

F i f ( ) d li d l t tibilit (b) f

- Semiconducting band gap of In4Se3

- Dispersive electron band and localized hole band of In4Se2.75

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APL (2009)Fermi surface (a) and generalized electron susceptibility (b) of In4Se2.75

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Summary and ConclusionsSummary and Conclusions

Summary

1. Low thermal conductivity • Extremely low thermal conductivity in the layered structure of disordered plane • CDW is an effective way to realize the disordered and layered structure

2. Band structural property of In4Se3-δ• Asymmetric electron hole band; hole localization• Asymmetric electron-hole band; hole localization

3. High thermoelectric performance and Peierls distortion• Peierls distortion of In4Se3-δ

• High thermoelectric figure-of-merit (ZT 1.48 @ 705 K)

Conclusions

g g ( @ )

Possible practical application for waste heat power generation of In4Se3-δ

Peierls distortion is a new pathway of thermoelectric materials development

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