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

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<4D6963726F736F667420506F776572506F696E74202D20C0CCC1BEBCF65FB9DFC7A5C0DAB7E1205BC8A3C8AF20B8F0B5E55D>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 gy 1Dept. 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
Low Thermal Conductivity and CDWLow Thermal Conductivity and CDW
Extremely low thermal conductivity
- 2-D layered WSe2 thin film Di d d l d t t- Disordered layered structure
- κ=0.04 W/mK
Charge Density Wave Charge Density Wave (CDW) - Strong electron-phonon coupling
)(εψ k
Strong electron phonon coupling - Density wave energy gap - Low D Lattice instability
kVk 2)0()0( '
2nd d t b ti th
The 7th Korea-US Nano Forum Iwha Women’s Univ., 6th April 2010
2a 2nd order perturbation theory
Thermoelectric properties of CDWThermoelectric properties of CDW
Toy model – CeTe2
Crystal structure of CeTe2 CeTe2 electron diffraction Te-layer distortion
K. Y. Shin et al. Phys. Rev. B (72) 85132 (2005)
Thermoelectricity in CeTe2
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)
The 7th Korea-US Nano Forum Iwha Women’s Univ., 6th April 2010
Thermal conductivity (left) and Seebeck coefficient of CeTe2-xSnx
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 l J. S. Rhyee et al. Nature ( )
plane of Peierls instability - High ZT (1.48 @705 K) for n-type materials
The 7th Korea-US Nano Forum Iwha Women’s Univ., 6th April 2010
In4Se3 crystal structure (2009) materials
Peierls distortion and Thermoelectricity Peierls distortion and Thermoelectricity
Band structure and Peierls distortion
2
2
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
The 7th Korea-US Nano Forum Iwha Women’s Univ., 6th April 2010
APL (2009) Fermi surface (a) and generalized electron susceptibility (b) of In4Se2.75
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
Possible practical application for waste heat power generation of In4Se3-δ
Peierls distortion is a new pathway of thermoelectric materials development