Experimental Observations on the Structural Transitions and Metallization in the Two-Dimensional Layered Compound of...

Cadmium phosphorous trisulfide (CdPS₃), a prototypical member of metal thio- and selenophosphates (MTPs), has garnered tremendous research interest due to its fundamental properties and potential for novel applications. In this paper, we conducted a comprehensive investigation on the structural evolution and electrical transport behaviors of CdPS₃ up to 59.1 GPa under different hydrostatic environments by means of Raman spectroscopy and electrical conductivity measurements. Under non-hydrostatic compression, CdPS₃ experienced a succession of structural modifications from C2/m to R3¯ phases at 1.4(5) GPa, then to the isostructural R3¯ phase at 7.8(5) GPa and sequentially to the P3¯1m phase at 29.8(11) GPa, followed by a semiconductor-to-metal transition at 51.3(8) GPa. Under hydrostatic pressurization, ~2.0 GPa pressure hysteresis for the R3¯-to-P3¯1m structural modification and metallization was identified, which can be reasonably interpreted by the impact of deviatoric stress. Upon decompression, the structural transitions of CdPS₃ were demonstrated to be reversible with the existence of considerable pressure hysteresis under different hydrostatic environments. Our findings on CdPS₃ not only lay a solid foundation for exploring the physicochemical properties of other MTPs under extreme conditions but also push forward its applications in high-performance multifunctional devices.