LCAO Calculations of (001) Surface Oxygen Vacancy Structure in Y-Doped BaZrO3

LCAO calculations have been used to study atomic and electronic structure of the oxygen vacancy at (001) ZrO2 termination of the cubic phase of Y-doped BaZrO3. By considering different positions of Y substituents, the vacancy formation energies are calculated relative to the stable phases of ZrO2 and Y2O3. It is demonstrated that the surface vacancy stability can be affected by the location depth of the nearest Y dopant atoms in the top surface layers. The calculated surface migration energy of 0.3 eV is small and thus we expect surface processes active already at moderate temperatures. The vacancy formation energy on the surface (1.3 eV) is much smaller than in the bulk (3.3 eV); thus we predict strong defect segregation towards the surface.