Effect of anomalous behavior of Be-doping on structural stability, bandgap and optical properties in comparison with Mg-doped BaZrO3 perovskite: insights from DFT calculations

Abstract

Effect of anomalous behavior of beryllium (Be) on structural stability, band gap engineering and optoelectronic properties in comparison with magnesium (Mg) doped BaZrO3 perovskite have been explored. All calculations have been performed, by constructing the supercell to overcome the boundary effects, with CASTEP code, established on DFT, by Perdew-Burke-Ernzerhof-Generalized-Gradient-Approximations (PBE-GGA) exchange correlation functional and USP (ultra-soft pseudo-potential). Various properties of the doped and pure compounds are probed such as the analysis of band structure, TDOS (total density of states), PDOS (partial density of states) and their effect on dielectric function. The substitution of Ba-atom with the Mg- and Be-atom change the lattice parameters and modify electronic structure of BaZrO3. In case of Mg and Be doping the value of band gap decreases from 3.119 to 2.844 eV and 0.886 eV. Due to doping of the Mg and Be doping valence band is shifted from R to G symmetry points whereas the conduction band is shifted from G to R symmetry points, with the emergence of new symmetry points, because of Mg- and Be-s-states and showing indirect band gap. From optical properties, a red shift in the absorption edge is noticed for both doped compounds. The static refractive index is also enhanced with Be-doping from of 2.2 to 2.32. The Be and Mg doping in BaZrO3 alters electronic and optical properties emphatically and models this doped material a very prospective contestant for optoelectronic devices.