A study of structural, electronic, elastic, phonon properties, and transition mechanism of wurtzite CdTe under high pressure

Abstract

Ab initio computational methods based on density functional theory to study the structural, electronic, elastic and phonon properties of Cadmium Telluride (CdTe) were applied. SIESTA method was used for calculations with the generalized gradient approximation (GGA) for the exchange-correlation functional and norm-conserving Troullier-Martins pseudopotentials. Our calculations are carried out to investigate the high-pressure behavior of the hexagonal wurtzite structured CdTe corresponding to the space group of P63mc. When increased hydrostatic pressure was applied on this structure of CdTe, phase transformation was obtained to a cubic structure with space group Fm3‾m at 10 GPa. During this phase transformation, the transition path was predicted as follows: P63mc→P21→Cmc21→P21→P21/m→Pmn21→Pmmn→Fm3‾→Fm3‾m. As the pressure continued to increase, phase transformation to an orthorhombic structure with space group Cmmm at 140 GPa occurred. During this transformation, the transition path was predicted as follows. Fm3‾m→R3‾m→P1‾→P4/mmm→Cmmm. As a result of the literature studies, the transition paths obtained in the study were estimated for the first time. In addition, the electronic properties of CdTe such as band structure and density of states for the obtained high-pressure phases were examined. Although the wurtzite structure of CdTe has a semiconductor character, the other obtained cubic and orthorhombic structures have a metallic character. In addition, in order to determine whether all phases of CdTe are mechanically and dynamically stable, we also examined the elastic and phonon properties respectively. As a result, the wurtzite and cubic structures of CdTe were determined to be both mechanically and dynamically stable, whereas the orthorhombic structure was unstable.