Electronic Structure and Optical Properties of SrBi₂A₂O₉(A=Nb,Ta)

The first-principles calculation is performed to investigate the energy band structures, density of states (DOS) and optical properties of SrBi₂A₂O₉ (A=Nb,Ta), by using density functional theory (DFT) with the generalized gradient approximation (GGA). The results show that the band−gap of SrBi₂Nb₂O₉ is smaller than that of SrBi₂Ta₂O₉, and that there are strong hybridizations of A−O bands, which play very important roles in the electronic properties and optical responses of SrBi₂A₂O₉. SrBi₂Ta₂O₉ stimulates much higher photocatalytic activity than SrBi₂Nb₂O₉, which is due to its suitable crystal structure.