Pressure-Induced Structural Phase Transition and Metallization of CrCl 3 under Different Hydrostatic Environments up to 50.0 GPa.

High-pressure structural, vibrational, and electrical transport properties of CrCl 3 were investigated by means of Raman spectroscopy, electrical conductivity, and high-resolution transmission electron microscopy under different hydrostatic environments using the diamond anvil cell in conjunction with the first-principles theoretical calculations up to 50.0 GPa. The isostructural phase transition of CrCl 3 occurred at 9.9 GPa under nonhydrostatic conditions. As pressure was increased up to 29.8 GPa, CrCl 3 underwent an electronic topological transition accompanied by a metallization transformation due to the discontinuities in the Raman scattering and electrical conductivity, which is possibly belonging to a typical first-order metallization phase transition as deduced from first-principles theoretical calculations. As for the hydrostatic condition, a ∼2.0 GPa pressure delay in the occurrence of two corresponding transformations of CrCl 3 was observed owing to the different deviatoric stress. Upon decompression, we found that the phase transformation from the metal to semiconductor in CrCl 3 is of good reversibility, and the obvious pressure hysteresis effect is observed under different hydrostatic environments. All of the obtained results on the structural, vibrational, and electrical transport characterizations of CrCl 3 under high pressure can provide a new insight into the high-pressure behaviors of representative chromium trihalides CrX 3 (X = Br and I) under different hydrostatic environments.