Oxygen vacancy segregation and space-charge effects in grain boundaries of dry and hydrated BaZrO3

A space-charge model is applied to describe the equilibrium effects of segregation of double-donor oxygen vacancies to grain boundaries in dry and wet acceptor-doped samples of the perovskite oxide BaZrO3. The grain boundary (GB) core vacancy concentrations and electrostatic potential barriers resulting from different vacancy segregation energies were evaluated. Density-functional calculations on vacancy segregation to the mirror-symmetric Sigma 3 (112) [(1) over bar 10] tilt grain boundary are also presented. Our results indicate that oxygen vacancy segregation can be responsible for the low grain boundary proton conductivity in BaZrO3 reported in the literature. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3681169]