Investigations of electronic, structural and optical properties of cubic A2ZnTeO6 (A = Ca, Sr, Ba) compounds via first-principles approaches

Abstract

Theoretical calculations are performed to investigate the electronic, structural and optical properties of double perovskite oxide A2ZnTeO6 (A = Ca, Sr, Ba). The calculations are based on the Density Functional Theory (DFT) using the WIEN2k code. The exchange–correlation potential is treated with generalized gradient approximation (GGA-PBE). Additionally, the Tran Blaha modified Becke-Johnson exchange potential (TB-mBJ) is employed for electronic and optical calculations due to that it gives very accurate results of band gap in solids. In order to estimate the ground state parameters, total energies are calculated with respect to cell volume. Also, the energies are fitted with Murnaghan equation of state. The estimated ground state parameters are comparable with the available experimental data. The band structure calculations reveal that these compounds exhibit semiconducting behavior with a direct band gap. To explore the optical transitions in these compounds, the real and imaginary parts of the dielectric function are analyzed at ambient conditions and the important optical constants are calculated and discussed.