Electronic Structure and Optical Properties of SrBi_(2)A_(2)O_(9)(A=Nb,Ta)

The first-principles calculation is performed to investigate the energy band structures,density of states(DOS)and optical properties of SrBi_(2)A_(2)O_(9)(A=Nb,Ta),by using density functional theory(DFT)with the generalized gradient approximation(GGA).The results show that the band−gap of SrBi_(2)A_(2)O_(9) is smaller than that of SrBi_(2)A_(2)O_(9),and that there are strong hybridizations of A−O bands,which play very important roles in the electronic properties and optical responses of SrBi_(2)A_(2)O_(9).SrBi_(2)A_(2)O_(9) stimulates much higher photocatalytic activity than SrBi_(2)A_(2)O_(9),which is due to its suitable crystal structure.