Calculations of selenium and cadmium concentration dependent elastic and thermal properties of zinc-blende specimens under CdxZn1-xSeyTe1-y quaternary system with density functional theory

Abstract

First principle based investigations on mechanical and thermal properties have been executed for the zinc-blende specimens constituting the CdxZn1-xSeyTe1-y system. Elastic stiffness constants of specimens have been increased with increasing selenium concentration at any fixed cadmium concentration, while reverse tendencies have been observed with increasing cadmium concentration at any fixed selenium concentration. Hardness of specimens has been increased with increasing selenium concentration at any fixed cadmium concentration, while it has been decreased with increasing cadmium concentration at any fixed selenium concentration. The phonon dispersion spectra indicate dynamical stability in each binary, but instability in each ternary and quaternary alloy in their zinc-blende structures. Mechanical stability, elastic anisotropy, compressibility, ductility, plasticity, mixing of covalent and ionic bonding with prominent role of covalent over ionic, prominent role of bending over stretching in chemical bonds and central nature of interatomic forces have been observed in each compound. Calculated Debye temperature has established ZnSe as the hardest and CdTe as the softest among all the compounds. The anharmonic nature of interactions between the atoms in any compound has been confirmed with respective calculated Gruneisen parameter. The computed thermal conductivity and melting point temperature of each specimen have also been reported in the present article.