First-principle study of the ferroelectricity and optical properties of the BaBi2Ta2O9

With the help of ab initio full-potential linearized augmented plane wave (FPLAPW) method, the calculations of the electronic structure and linear optical properties are carried out for BaBi2Ta2O9 (BBT) for the first time. It is found that these quite strong Ta–O and Bi–O hybridization is the primary source for ferroelectricity. The optical spectra are assigned to interband contribution between O 2p valence bands to Bi 6p conduction bands in the low-energy region and between O 2p valence bands and Ta 6s, 5d conduction bands in the high-energy region.