Effects of oxygen group elements on thermodynamic stability, electronic structures and optical properties of the pure and pressed BaTiO3 perovskite

Abstract

Thermodynamic stability, electronic structures, and optical properties of the pure and pressed BaTiO3 doped with different concentrations of oxygen group elements (Se, Te, and S) are investigated using the Density Functional Theory. It was found that when chalcogens elements in BaTiO3 compound substitute oxygen atoms, the forbidden gap is significantly decreased from 3.010 eV (for pressed BaTiO3) to 0.000 eV (for Te-doped BaTiO3 and pressed Se/Te-doped BaTiO3) indicating that chalcogens impurities have a crucial role in the reduction of the forbidden band of BaTiO3 compound. Moreover, 2.3% of compressive strain itself with and without the presence of chalcogens impurities transforms the pure BaTiO3 from indirect to direct semiconductor. Furthermore, the calculated formation energy confirms the thermodynamic stability of all studied compounds. Additionally, the doping changed the absorption behavior of BaTiO3 making the compound more useful for optoelectronic applications due to the introduction of addition carries into the system after the inclusion of chalcogens impurities.