Pressure-induced coupled structural–electronic transition in SnS2 under different hydrostatic environments up to 39.7 GPa

Abstract

A series of in situ high-pressure Raman spectroscopy and electrical conductivity experiments have been performed to investigate the vibrational and electrical transport properties of SnS₂ under non-hydrostatic and hydrostatic environments. Upon compression, an coupled structural–electronic transition in SnS₂ occurred at 30.2 GPa under non-hydrostatic conditions, which was evidenced by the splitting of the E_g mode and the discontinuities in Raman shifts, Raman full width at half maximum (FWHM) and electrical conductivity. However, the coupled structural–electronic transition took place at a higher pressure of 33.4 GPa under hydrostatic conditions, which may be due to the influence of the pressure medium. Furthermore, our first-principles theoretical calculations results revealed that the bandgap energy of SnS₂ decreased slowly with increasing pressure and it closed in the pressure range of 30–40 GPa, which agreed well with our Raman spectroscopy and electrical conductivity results. Upon decompression, the recoverable Raman peaks and electrical conductivity indicated that the coupled structural–electronic transition was reversible, which was further confirmed by our HRTEM observations.