Electron-phonon coupling and electronic thermoelectric properties of n-type PbTe driven near the soft-mode phase transition via lattice expansion

Cao, Jiang; Dangić, Đorđe; Querales-Flores, José D.; Fahy, Stephen B.; Savić, Ivana

Electron-phonon coupling and electronic thermoelectric properties of n-type PbTe driven near the soft-mode phase transition via lattice expansion

Files

PhysRevB.104.045202.pdf(740.12 KB)

Published Version

Date

2021-07-12

Authors

Cao, Jiang

Dangić, Đorđe

Querales-Flores, José D.

Fahy, Stephen B.

Savić, Ivana

Publisher

American Physical Society

Published Version

10.1103/PhysRevB.104.045202

Abstract

IV–VI materials are some of the most efficient bulk thermoelectric materials due to their proximity to soft-mode phase transitions, which leads to low lattice thermal conductivity. It has been shown that the lattice thermal conductivity of PbTe can be considerably reduced by bringing PbTe closer to the phase transition, e.g., via lattice expansion. However, the effect of soft phonon modes on the electronic thermoelectric properties of such a system remains unknown. Using first-principles calculations, we show that the soft zone-center transverse optical phonons do not deteriorate the electronic thermoelectric properties of PbTe driven closer to the phase transition via lattice expansion due to external stress, and thus they enhance the thermoelectric figure of merit. We find that the optical deformation potentials change very weakly as the proximity to the phase transition increases, but the population and scattering phase space of soft phonon modes increase. Nevertheless, scattering between electronic states near the band edge and soft optical phonons remains relatively weak even very near the phase transition.

Keywords

Electron-phonon coupling , Electronic thermoelectric properties , n-type PbTe , Soft-mode phase transition , Lattice expansion

Citation

Cao, J., Dangić, Đ., Querales-Flores, J. D., Fahy, S. and Savić, I. (2021) 'Electron-phonon coupling and electronic thermoelectric properties of n-type PbTe driven near the soft-mode phase transition via lattice expansion', Physical Review B, 104, 045202 (8pp). doi: 10.1103/PhysRevB.104.045202