|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Computational Thermodynamics and Kinetics
||Anharmonic Phonons in Low-symmetry FeGe2 at the Paramagnetic Phase
||Yang Shen, Hillary Smith, Dennis Kim, Fred Yang, Doug Abernathy, Matt Stone, Brent Fultz
|On-Site Speaker (Planned)
By inelastic neutron scattering experiments, we measured phonon density of states (DOS) from 300K to 1050K and phonon dispersions at 20, 300, 500 and 635K for FeGe<SUB>2</SUB>. Fe partial DOS was also obtained by nuclear resonant inelastic x-ray scattering at room temperature. DFT calculations with quasiharmonic approximation at elevated temperatures were performed using our measured lattice constants from neutron diffraction experiments. We found that there is a larger broadening feature in the high-energy phonon modes than the low-energy phonon modes, while the fractional phonon energy shifts are almost the same with temperature, requiring compensating contributions from the quartic and quasiharmonic terms for different phonon modes. It is shown that those anharmonic optical phonons at the paramagnetic phase originates from the Fe-Ge bonds, due to the asymmetrical Ge atomic sites. Beyond the quasiharmonic model, the anharmonicity contributes approximately 5% of the total phonon entropy estimated from the neutron-weighted DOS at 1050K.
||Planned: Supplemental Proceedings volume