ABO3 perovskite as well as BaF2, SrF2 and CaF2 bulk and surface F-center first principles predictions

Abstract

We, at the ab initio level, simulated the rearrangement magnitudes of the adjacent neighboring ions, surrounding the (100) surface F-center in ABO3 perovskite matrixes. They are noticeably greater than the respective ionic shift magnitudes of the adjacent neighboring ions surrounding the bulk F-center. In ABO3 perovskites, the electron charge is noticeably better bounded on the inside of the bulk oxygen vacancy, as interior the respective (100) surface vacancy. The oxygen vacancy formation energy, located on the (100) surface of ABO3 perovskites, as a rule, is smaller as in the bulk. This slight energy distinction encourages the oxygen vacancy segregation from the ABO3 perovskite bulk to their (100) surfaces. The ABO3 complex oxide (100) surface F-center generated defect levels are positioned nearer to the (100) surface CB bottom than the bulk F-center generated respective defect levels. In contrary, the BaF2, SrF2 and CaF2, both, surface and bulk F-center charges are well localized inside the fluorine vacancy. The ionic rearrangement magnitudes of the adjacent neighboring ions, surrounding the surface and bulk F-centers in BaF2, SrF2 and CaF2 matrixes, are much smaller regarding the respective situation in ABO3 perovskites.