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

As a representative homologous series, tin-bearing metallic chalcogenides (SnS) 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 SnS 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 SnS 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 SnS not only unveils its composition-structure-property relation but also advances the in-depth exploration for other IVA-VIA metallic chalcogenides.