Revealing the structural, elastic and thermodynamic properties of CdSexTe1−x (x = ​0, 0.25, 0.5, 0.75, 1)

Abstract

First-principles calculations are carried out to perform the structural properties using two dimensional search of equation of state (EOS), elastic constants and thermodynamic properties for zinc-blende (ZB) and wurtzite (WZ) phases of CdSexTe1−x alloys for all compositions x (x = 0, 0.25, 0.5, 0.75, 1). We have used the full-potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT), which has been implanted in the WIEN2k code, along with the improved generalized gradient approximation (PBE-GGA) to treat exchange-correlation functional. The mechanical and thermodynamic properties of CdSexTe1−x alloys are studied using the optimized lattice parameters from two dimensional search of EOS at zero pressure. The ZB and WZ phases of the ternary CdSexTe1−x alloys are found to be mechanically stable within PBE-GGA exchange-correlation over all the range of the Te concentrations (x = 0, 0.25, 0.5, 0.75, 1). We have found that the CdSe is mechanically the strongest material in the ternary CdSexTe1−x alloys. We concluded that the calculated values of Cauchy pressure and Poisson's ratio predict that the ionic bonds for both ZB and WZ phases of CdSexTe1−x ternary alloys are more dominant for all compositions of x(x = 0, 0.25, 0.5, 0.75, 1) within PBE-GGA exchange-correlation. Our results exhibit a non-linear relationship between elastic constants and Se concentrations. Moreover, the elastic properties of cubic (ZB) and hexagonal (WZ) phases of CdSexTe1−x alloys, including elastic constants, bulk and shear moduli are calculated and compared with available theoretical and experimental results, good agreement was found.