声子
凝聚态物理
材料科学
Crystal(编程语言)
态密度
物理
计算机科学
程序设计语言
作者
Ravhi S. Kumar,Han Liu,Quan Li,Yuming Xiao,Paul Chow,Yue Meng,Michael Y. Hu,E. Ercan,Russell J. Hemley,Changfeng Chen,Andrew Cornelius,Z. Fisk
标识
DOI:10.1021/acs.jpcc.4c00626
摘要
The strongly correlated material FeSi displays several unusual thermal, magnetic, and structural properties under varying pressure–temperature (P–T) conditions. It is a potential thermoelectric alloy and a material with several geochemical implications as a possible constituent at the Earth's core-mantle boundary (CMB). Previous theoretical studies predicted a pressure-induced B20–B2 transition at ambient temperature below 40 GPa; however, experimentally, the structural transition is observed only under high P–T conditions. In this study, we have performed high-pressure powder X-ray diffraction (XRD) up to 90 GPa and Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements up to 120 GPa to understand the phase stability and lattice dynamics. Our study provides evidence for a nonhydrostatic stress-induced B20–B2 transition in FeSi at around 36 GPa. We deduced the Fe partial phonon density of states (PDOS) and thermal parameters from NRIXS measurements up to 120 GPa and compared them with density functional theory (DFT) calculations. Additionally, the computations show pressure-induced metallization and band gap closing at around 12 GPa.
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