Electronic properties of ferroelectric SrBi2Ta2O9, SrBi2Nb2O9, and PbBi2Nb2O9 with optimized structures

Electronic properties of ferroelectric SrBi2Ta2O9 (SBT) SrBi2Nb2O9 (SBN) and PbBi2Nb2O9 (PBN) have been investigated using a first-principles calculational method with optimized structures. In optimized SBT, the displacement of Ta in TaO6 octahedra is small, while the displacement of Nb in NbO6 octahedra is larger in optimized SBN. In optimized PBN, on the other hand, due to the hybridization between Pb 6s and O 2p, the displacement of NbO6 octahedra is larger than that in SBN.