常压和高压下的锡硒化合物
Tin-selenium compounds at ambient and high pressures
摘要：
采用基于密度泛函理论（DFT）的第一性原理演化晶体结构搜索方法，在0 ~ 100 GPa压力范围内系统地研究了由Sn和Se原子组成的SnxSey晶体化合物.在没有任何先前输入的情况下发现SnSe和SnSe 2的所有已知实验相。在2.5GPa下，SnSe-Pnma相向SnSe-Cmcm相的二级多晶相变。最初是半导体的，这个相在7.3 GPa时变成金属。当压力进一步增加到36.6GPa时，SnSe-Cmcm相转变为CsCl型SnSe-Pm 3 m相，其在甚至更高的压力下保持稳定。发现具有不同化学计量比的金属化合物Sn_3Se_4-I_（43）d在18 ~ 70 GPa范围内是稳定的。已知的半导体二硒化锡SnSe 2-P3 m1相被发现从环境压力直到18 GPa是化学稳定的。最初是半导体的，它在超过8 GPa的压力下经历金属化。
英文摘要：
SnxSey crystalline compounds consisting of Sn and Se atoms of varying composition are systematically investigated at pressures from 0 to 100 GPa using the first-principles evolutionary crystal structure search method based on density functional theory (DFT). All known experimental phases of SnSe and SnSe2 are found without any prior input. A second order polymorphic phase transition from SnSe-Pnma phase to SnSe-Cmcm phase is predicted at 2.5 GPa. Initially being semiconducting, this phase becomes metallic at 7.3 GPa. Upon further increase of pressure up to 36.6 GPa, SnSe-Cmcm phase is transformed to CsCl-type SnSe-Pm3m phase, which remains stable at even higher pressures. A metallic compound with different stoichiometry, Sn3Se4-I43d, is found to be thermodynamically stable from 18 GPa to 70 GPa. Known semiconductor tin diselenide SnSe2-P3m1 phase is found to be thermodynamically stable from ambient pressure up to 18 GPa. Initially being semiconducting, it experiences metalization at pressures above 8 GPa.
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