Structural\nand Electronic Phase Transitions in Three\nStable Tin–Sulfur Metallic Chalcogenides under High Pressure

As a representative homologous series, tin-bearing metallic\nchalcogenides\n(Sn<sub><i>x</i></sub>S<sub><i>y</i></sub>) have\nsparked considerable attention because of their stoichiometric compositions\nand structural diversities. In this work, three stable compounds,\nSnS, Sn<sub>2</sub>S<sub>3</sub>, and SnS<sub>2</sub>, were screened\nfrom Sn<sub><i>x</i></sub>S<sub><i>y</i></sub> and a comprehensive investigation on their structural and electrical\ntransport properties was performed up to 60.1 GPa using a diamond\nanvil cell (DAC) under different hydrostatic environments. Upon nonhydrostatic\ncompression, SnS underwent the <i>Pnma</i>-to-<i>Cmcm</i> transition accompanied by metallization at 7.6 GPa, followed by\nthe <i>Cmcm</i>-to-<i>Pm</i>3̅<i>m</i> transformation at 17.8 GPa. For SnS<sub>2</sub>, the pressure-induced\nmetallization and isostructural phase transition (IPT) occurred successively\nat 31.2 and 46.6 GPa, respectively. As an intermediate composition,\nSn<sub>2</sub>S<sub>3</sub> first experienced an IPT at 10.8 GPa,\nand then, the <i>Pnma</i>-to-<i>Cmcm</i> transition\nconcomitantly with metallization occurred at 16.9 GPa, analogous to\nthe high-pressure structural transformation routes of SnS and SnS<sub>2</sub>. The 0.6–5.4 GPa pressure hysteresis was detectable\nfor the phase transitions of Sn<sub><i>x</i></sub>S<sub><i>y</i></sub> under quasi-hydrostatic and hydrostatic\nconditions owing to the influence of deviatoric stress. In comprehensive\nconsideration of our high-pressure Raman scattering and electrical\nconductivity results, the systematic construction of a pressure-phase\nstate diagram on Sn<sub><i>x</i></sub>S<sub><i>y</i></sub> not only unveils its composition–structure–property\nrelation but also advances the in-depth exploration for other IVA–VIA\nmetallic chalcogenides.