First principle calculations of electronic, band structural, and optical properties of BixSr1-xTiO3 perovskite

Abstract Based on the first-principles plane-wave ultrasoft pseudopotential method, we set up models of perovskite-type oxides Bi x Sr 1-x TiO 3 (x = 0, 0.25, 0.5, 0.625, 1), and the geomertry optimization, the electronic and band structure were studied. The calculation results show that the binding energy decreases in Bi x Sr 1-x TiO 3 after Sr 2+ replaced by Bi 3+ . The calculations of the band structure show that Bi x Ba 1-x TiO 3 are direct band gap semiconductors. The partial substitution of Bi 3+ ions can increase the band gap and the absorption spectra ranges shift blue, and the values of band gaps are in the order of Bi 0.625 Sr 0.375 TiO 3  > Bi 0.5 Sr 0.5 TiO 3  > Bi 0.25 Sr 0.75 TiO 3  > SrTiO 3  > BiTiO 3 , and the absorption spectrum becomes wider in the order of Bi 0.625 Sr 0.375 TiO 3  > BiTiO 3  > Bi 0.5 Sr 0.5 TiO 3  > Bi 0.25 Sr 0.75 TiO 3  > SrTiO 3 . Based on the density of states, the top of the valence band is hybridized by O-2p and Sr-5s and the bottom of the conduction band state is mainly constituted by the Ti-3d states and Bi-6p states. The regulation of photo-catalytic activity of the perovskite SrTiO 3 can be realized by Bi ions substituting for Sr ions, and Bi-based perovskite BiTiO 3 will be a potential photocatalytic material.