Pressure-Induced Structural Phase Transition and Metallization of CrCl3 under Different Hydrostatic Environments up to 50.0 GPa

High-pressure structural, vibrational, and electrical transport properties of CrCl3were investigated by means of Raman spectroscopy, electrical conductivity, and high-resolutiontransmission electron microscopy under different hydrostatic environments using the diamondanvil cell in conjunction with thefirst-principles theoretical calculations up to 50.0 GPa. Theisostructural phase transition of CrCl3occurred at 9.9 GPa under nonhydrostatic conditions. Aspressure was increased up to 29.8 GPa, CrCl3underwent an electronic topological transitionaccompanied by a metallization transformation due to the discontinuities in the Ramanscattering and electrical conductivity, which is possibly belonging to a typicalfirst-ordermetallization phase transition as deduced fromfirst-principles theoretical calculations. As for thehydrostatic condition, a similar to 2.0 GPa pressure delay in the occurrence of two correspondingtransformations of CrCl3was observed owing to the different deviatoric stress. Upondecompression, we found that the phase transformation from the metal to semiconductor inCrCl3is of good reversibility, and the obvious pressure hysteresis effect is observed underdifferent hydrostatic environments. All of the obtained results on the structural, vibrational, andelectrical transport characterizations of CrCl3under high pressure can provide a new insight into the high-pressure behaviors ofrepresentative chromium trihalides CrX3(X = Br and I) under different hydrostatic environments.

Automated summary

This study investigated the high-pressure behavior of CrCl3 under different hydrostatic conditions using various experimental techniques and theoretical calculations. The results revealed an isostructural phase transition at 9.9 GPa under nonhydrostatic conditions and a pressure delay effect under hydrostatic conditions. The phase transformation from metal to semiconductor in CrCl3 was found to be reversible, and a pressure hysteresis effect was observed under different hydrostatic environments.