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 core vacancy concentrations and electrostatic potential barriers resulting from different vacancy segregation energies are evaluated. Density-functional calculations on vacancy segregation to the mirror-symmetric \Sigma 3 (112) [-110] 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. 
B. Joakim Nyman, Edit E. Helgee, and G\"oran Wahnstr\"om
cond-mat.mtrl-sci cond-mat.mes-hall