Effect of Pressure and Temperature on Structural Stability of MoS2

The crystal structure and spectral properties of bulk MoS2 were investigated at high pressures up to 51 GPa using a diamond anvil cell with synchrotron radiation in addition to high temperature X-ray diffraction and high pressure Raman spectroscopic analysis. While the crystal structure of MoS2 is stable on increasing temperature, results of high pressure experiments show a pressure-induced isostructural hexagonal distortion to a 2H(a)-hexagonal P6(3)/mmc phase around 26 GPa as predicted by theoretical calculations reported earlier. The 2H(a)-hexagonal phase coexists with the ambient 2H(c) phase up to 51 GPa, the highest pressure achieved in our experiments. The Raman data obtained in our high pressure experiments show consistent changes in the vibrational modes. Furthermore, the diffraction data obtained for the shocked MoS2 to pressures 8 GPa is found to be structurally resilient.