Electronic structures and ferroelectric instabilities of cubic AVO(3) (A = Sr, Ba, and Pb) perovskites by first-principles calculations.

The electronic properties and ferroelectric transition behaviors of three AVO(3) (A = Sr, Ba, and Pb) compounds are investigated by first-principles density functional theory (FP-DFT) in combination with soft-mode theory. The band structures and projection density of states (PDOS) confirm that the bonding properties of SrVO(3) and BaVO(3) are rather similar to each other, but different to that of PbVO(3). The bonding differences determine the ferroelectric transition behaviors of these compounds. For SrVO(3) and BaVO(3), no ferroelectric instability is observed and they possess cubic structures. The covalent interactions of Pb-O pairs are very important for the ferroelectric instability of PbVO(3). In comparison to PbTiO(3), we found that the V-O interactions further enhance the ferroelectric instability of PbVO(3), and therefore PbVO(3) shows a much larger tetragonal distortion than PbTiO(3).