Theoretical investigations on HgTe chalcogenide materials under high pressure

Abstract

First principle computations based on Density Functional Theory are made to investigate structural, mechanical, electronic properties and phase transition behaviors of HgTe chalcogenide material. It is obtained that the phase transition sequence of HgTe material is Zincblende -> Cinnabar -> Rocksalt -> Cmcm -> CsCl at 2.35 GPa, 5.95 GPa, 14.29 GPa, 52.37 GPa, respectively. The negative C-44 and C-s values of the CsCl structure under ambient conditions indicate that this structure is mechanically unstable against the applied deformations. The small values of the elastic constants of HgTe in the cinnabar structure reveal that this structure is less resistant to deformations. The low value of tetragonal shear constant C-s of the parent phase reflects the elastic instability leading to a pressure-induced phase transition. According to our isotropic mechanical results obtained from the Voigt-Reuss-Hill (VRH) approach, the ductility behavior improves in the rocksalt and Cmcm structures which are high-pressure phases. The zincblende and cinnabar structures show semimetal and semiconductor properties in the electronic band calculations, respectively, while rocksalt, Cmcm and CsCl structures are found to be of metallic character.