Structural,elastic, electronic and optical properties of the cubic perovskite BiAlO3

We report first-principles study of structural, elastic, electronic and optical properties of the cubic perovskite-type BiAlO₃ using the pseudopotential plane waves method within the local density approximation. The calculated structural parameters are in good agreement with previous calculations. The elastic constants and their pressure dependence are calculated using the static finite strain technique. A linear pressure dependence of the elastic stiffness is found. Band structures show that BiAlO₃ has an indirect band gap between the occupied O 2p and unoccupied Bi 6p states. The density of states and Mulliken charge populations analysis shows that Al–O and Bi–O bonds are covalent with a strong hybridization. The variation of the gap versus pressure is well fitted to a quadratic function and an indirect to direct band gap transition occurs at 15.5 GPa. Furthermore, in order to understand the optical properties of BiAlO₃, the dielectric function, absorption coefficient, refractive index, extinction coefficient, optical reflectivity and electron energy loss are calculated for radiation up to 30 eV.