Structural and Electronic Phase Transitions in Three Stable Tin-Sulfur Metallic Chalcogenides under High Pressure.

As a representative homologous series, tin-bearing metallic chalcogenides (SnxSy) have sparked considerable attention because of their stoichiometric compositions and structural diversities. In this work, three stable compounds, SnS, Sn2S3, and SnS2, were screened from SnxSy and a comprehensive investigation on their structural and electrical transport properties was performed up to 60.1 GPa using a diamond anvil cell (DAC) under different hydrostatic environments. Upon nonhydrostatic compression, SnS underwent the Pnma-to-Cmcm transition accompanied by metallization at 7.6 GPa, followed by the Cmcm-to-Pm3̅m transformation at 17.8 GPa. For SnS2, the pressure-induced metallization and isostructural phase transition (IPT) occurred successively at 31.2 and 46.6 GPa, respectively. As an intermediate composition, Sn2S3 first experienced an IPT at 10.8 GPa, and then, the Pnma-to-Cmcm transition concomitantly with metallization occurred at 16.9 GPa, analogous to the high-pressure structural transformation routes of SnS and SnS2. The 0.6-5.4 GPa pressure hysteresis was detectable for the phase transitions of SnxSy under quasi-hydrostatic and hydrostatic conditions owing to the influence of deviatoric stress. In comprehensive consideration of our high-pressure Raman scattering and electrical conductivity results, the systematic construction of a pressure-phase state diagram on SnxSy not only unveils its composition-structure-property relation but also advances the in-depth exploration for other IVA-VIA metallic chalcogenides.