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

no code implementations • 20 Jan 2021 • Jiang Cao, Đorđe Dangić, José D. Querales-Flores, Stephen Fahy, Ivana Savić

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.

Materials Science Computational Physics

The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

no code implementations • 15 Dec 2020 • Đorđe Dangić, Olle Hellman, Stephen Fahy, Ivana Savić

However, the $\kappa$ of GeTe increases at the ferroelectric phase transition near $700$ K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in $\kappa$ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase.

Materials Science