Atomic and electronic structure of perfect and defective PbZrO3 perovskite:: Hybrid DFT calculations of cubic and orthorhombic phases

The structural and electronic properties of pure cubic and low-temperature orthorhombic PbZrO3 (antiferroelectric phase), as well as cubic PbZrO3 containing single F-centers (neutral oxygen vacancies) have been simulated by means of ab initio hybrid density functional calculations. We observed a substantial increase of the Pb-O bond covalency in ideal orthorhombic PbZrO3 with respect to its cubic phase. Relatively large displacement of four Pb atoms nearest to the F-center (0.25 angstrom towards the defect) could affect the PbZrO3 ferroelectric properties. An O vacancy in the bulk PbZrO3 attracts approximate to 0.7 e, and the remaining electron density from the missing O2- is localized mostly on four nearest Pb atoms. This leads to appearance of an energy level in the middle of the band gap of cubic PbZrO3, unlike the shallow F-level found in SrTiO3. (c) 2007 Elsevier B.V. All rights reserved.