Observation of Structural Transition and Metallization in a van der Waals Diamagnet ZnPS₃ via Pressure Manipulation

Zinc phosphorus trisulfide (ZnPS₃), one of the prototypical examples of diamagnetic metal phosphorus trichalcogenides (MPTs), has recently ignited extensive research into next-generation photocatalysis and energy storage. In this paper, the structural evolution and electrical transport properties of ZnPS₃ have been systematically investigated using Raman scattering spectroscopy and electrical conductivity coupled with first-principles calculations at high pressures up to 52.8 GPa under different pressure conditions. Upon application of nonhydrostatic pressure, ZnPS₃ may undergo a C2/m-to-P3̅1m structural modification at 5.5 GPa arising from the prominent contraction in interlayer distance as well as the P-Zn-P and P-S-P bond angles. Upon further pressurization to 36.8 GPa, ZnPS₃ experienced a semiconductor-to-metal transition evidenced by the high conductivity value and the positive-to-negative conversion in temperature-dependent electrical conductivity relations. Nevertheless, the comparable C2/m-to-P3̅1m structural transition pressure and an approximate 6.0 GPa pressure delay in metallization under hydrostatic conditions were due to the impact of deviatoric stress. On decompression, a reversible phase transition was demonstrated by the resumable Raman spectra and electrical conductivity magnitudes under different pressure conditions. Our research on ZnPS₃ not only offers an insightful perspective on the fundamental physics of MPTs under extreme conditions but also establishes a basis for further investigation into its potential applications.