|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Hume-Rothery Award Symposium: Thermodynamics of Materials
||Orbitally-driven Giant Phonon Anharmonicity in SnSe
||Chen Li, Jiawang Hong, Andrew F May, Dipanshu Bansal, Songxue Chi, Tao Hong, Jie Ma, Georg Ehlers, Olivier Delaire
|On-Site Speaker (Planned)
Understanding elementary excitations and their couplings in condensed matter systems is critical to develop better energy-conversion devices. In thermoelectric materials, the heat-to-electricity conversion efficiency is directly improved by suppressing the propagation of phonon quasiparticles responsible for macroscopic thermal transport. The material with the current record for thermoelectric conversion efficiency, SnSe, achieves an ultra-low thermal conductivity, but the mechanism enabling this strong phonon scattering remains largely unknown. Using inelastic neutron scattering and first-principles simulations, we mapped the four-dimensional phonon dispersion surfaces of SnSe, and revealed the origin of ionic-potential anharmonicity responsible for the unique properties of SnSe. We show that the giant phonon scattering arises from an unstable electronic structure, with orbital interactions leading to a ferroelectric-like lattice instability. The present results provide a microscopic picture connecting electronic structure and phonon anharmonicity in SnSe, and offers new insights on how electron-phonon and phonon-phonon interactions may lead to its ultra-low thermal conductivity.
||Planned: A print-only volume