LaBa2Fe3O8 cubic perovskite; oxygen-nonstoichiometry defects and conductivity

Point defects behind nonstoichiometry of the highly oxygen-vacant LaBa2FeIII3O8 single-perovskite structure are studied by quenching a set of nine samples close to FeIII from equilibria at two partial pressures of oxygen, pO2, at four temperatures T. This supports a simplified defect model that fits well the high-temperature electrical conductivity around and below the FeIII point, while deviating somewhat in the oxidized range. The conductivity fitted by sum of its electronic and ionic components versus T and pO2 in the surrounding gas reveals a good oxygen-ionic conductor. Oxygen diffusion behind conductivity transients upon a pO2 change is discussed.