Electronic and optical properties of pure and ni/ sr doped bay2o6 (y=ta, nb) compounds: Theoretical study

Perovskite-type oxides, like BaNb₂O₆ (BNO) and BaTa₂O₆ (BTO) compounds, have garnered attention due to their wide band gap (EF)s and adjustable dielectric properties, which have application in technological areas. One can greatly affect their structural, electrical, and optical properties of compound with increasing or decreasing the Eg via dopant. The purpose of this study was to compute electronic and optical characteristics of BN0 and BTO with or without dopant elements. Ni and Sr were selected as a dopant element in study. The used computational tools have four embedded potentials, which are to be used for including exchange-correlation effects in calculation. While PBE-GGA has been yielded the best theoretical lattice constants for BNO, PBEsol-GGA provided the most accurate lattice constants for BTO. The rest of calculation was performed to obtain electronic band structure, density of states and optical parameters like the dielectric function, absorption, reflectivity, refractive index, optical conductivity and extinction coefficient with PBE-GGA or PBEsol-GGA depending on studied compound. According to the optimized lattice constants, BTO exhibits greater density and stability because of stronger Ta–O hybridization, as evidenced by its smaller equilibrium volume and lower total energy compared to BNO. The Eg values for BNO and BTO were 4.1 eV and 3.85eV, respectively. In principle, Eg could be either larger or smaller than one of the undoped host crystal. Sr doping maintained the semiconducting nature and improved UV absorption, whereas Ni doping reduced the Eg and introduced metallic-like behavior. According to optical spectra, BNO shows higher reflectivity, stronger anisotropy and stronger absorption in the ultraviolet region, while BTO shows isotropic behavior with smooth, broad peaks. The results demonstrate doping method enhances the characteristics of oxide-based materials for upcoming optoelectronic and electronic applications.