Proton Conduction in Nonstoichiometric ∑3 BaZrO3 (210)[001] Tilt Grain Boundary Using Density Functional Theory

Abstract

We investigate proton conduction in a nonstoichiometric ∑3 BaZrO3 (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as −0.70 and −0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature. Key words: Proton conduction, Nonstoichiometric grain boundary, Density functional theory, Space charge layer