Ab-initio study of structural, elastic, electronic and thermodynamic properties of Ba_xSr_1−xS ternary alloys

The structural, elastic, electronic and thermodynamic properties of Ba_xSr_1−xS ternary alloys have been investigated using the full-potential (linearized) augmented plane wave method. The ground state properties, such as lattice constant, bulk modulus and elastic constants, are in good agreement with numerous experimental and theoretical data. The dependence of the lattice parameters, bulk modulus and band gap on the composition x was analyzed. Deviation of the lattice constant from Vegard’s law and the bulk modulus from linear concentration dependence (LCD) was observed. The microscopic origins of the gap bowing were explained by using the approach of Zunger et al. The thermodynamic stability of Ba_xSr_1−xS alloy was investigated by calculating the excess enthalpy of mixing, ΔH_m and the calculated phase diagram showed a broad miscibility gap with a critical temperature.