Abstract
The layered semiconductor SnSe is one of the highest-performing thermoelectric materials known. We demonstrate, through a first-principles lattice-dynamics study, that the high-temperature Cmcm phase is a dynamic average over lower-symmetry minima separated by very small energetic barriers. Compared to the low-temperature Pnma phase, the Cmcm phase displays a phonon softening and enhanced three-phonon scattering, leading to an anharmonic damping of the low-frequency modes and hence the thermal transport. We develop a renormalization scheme to quantify the effect of the soft modes on the calculated properties, and confirm that the anharmonicity is an inherent feature of the Cmcm phase. These results suggest a design concept for thermal insulators and thermoelectric materials, based on displacive instabilities, and highlight the power of lattice-dynamics calculations for materials characterization.
| Original language | English |
|---|---|
| Article number | 075502 |
| Journal | Physical Review Letters |
| Volume | 117 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 2016 Aug 10 |
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All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
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Anharmonicity in the High-Temperature Cmcm Phase of SnSe : Soft Modes and Three-Phonon Interactions. / Skelton, Jonathan M.; Burton, Lee A.; Parker, Stephen C.; Walsh, Aron; Kim, Chang Eun; Soon, Aloysius; Buckeridge, John; Sokol, Alexey A.; Catlow, C. Richard A.; Togo, Atsushi; Tanaka, Isao.
In: Physical Review Letters, Vol. 117, No. 7, 075502, 10.08.2016.Research output: Contribution to journal › Article
TY - JOUR
T1 - Anharmonicity in the High-Temperature Cmcm Phase of SnSe
T2 - Soft Modes and Three-Phonon Interactions
AU - Skelton, Jonathan M.
AU - Burton, Lee A.
AU - Parker, Stephen C.
AU - Walsh, Aron
AU - Kim, Chang Eun
AU - Soon, Aloysius
AU - Buckeridge, John
AU - Sokol, Alexey A.
AU - Catlow, C. Richard A.
AU - Togo, Atsushi
AU - Tanaka, Isao
PY - 2016/8/10
Y1 - 2016/8/10
N2 - The layered semiconductor SnSe is one of the highest-performing thermoelectric materials known. We demonstrate, through a first-principles lattice-dynamics study, that the high-temperature Cmcm phase is a dynamic average over lower-symmetry minima separated by very small energetic barriers. Compared to the low-temperature Pnma phase, the Cmcm phase displays a phonon softening and enhanced three-phonon scattering, leading to an anharmonic damping of the low-frequency modes and hence the thermal transport. We develop a renormalization scheme to quantify the effect of the soft modes on the calculated properties, and confirm that the anharmonicity is an inherent feature of the Cmcm phase. These results suggest a design concept for thermal insulators and thermoelectric materials, based on displacive instabilities, and highlight the power of lattice-dynamics calculations for materials characterization.
AB - The layered semiconductor SnSe is one of the highest-performing thermoelectric materials known. We demonstrate, through a first-principles lattice-dynamics study, that the high-temperature Cmcm phase is a dynamic average over lower-symmetry minima separated by very small energetic barriers. Compared to the low-temperature Pnma phase, the Cmcm phase displays a phonon softening and enhanced three-phonon scattering, leading to an anharmonic damping of the low-frequency modes and hence the thermal transport. We develop a renormalization scheme to quantify the effect of the soft modes on the calculated properties, and confirm that the anharmonicity is an inherent feature of the Cmcm phase. These results suggest a design concept for thermal insulators and thermoelectric materials, based on displacive instabilities, and highlight the power of lattice-dynamics calculations for materials characterization.
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U2 - 10.1103/PhysRevLett.117.075502
DO - 10.1103/PhysRevLett.117.075502
M3 - Article
VL - 117
JO - Physical Review Letters
JF - Physical Review Letters
SN - 0031-9007
IS - 7
M1 - 075502
ER -