First-principles modelling of complex perovskite (Ba1-xSrx)(Co1-yFey)O3-δ for solid oxide fuel cell and gas separation membrane applications

The results of the first principles spin-polarized DFT calculations of the atomic and electronic structure of a complex perovskite (Ba1-xSrx)(Co1-yFey)O3-δ (BSCF) used as a cathode material for solid oxide fuel cells (SOFC) and gas separation membranes are presented and discussed. The formation energies of oxygen vacancies are found to be considerably smaller than in other magnetic perovskites, e.g. (La,Sr)MnO3, which explains the experimentally observed strong deviation of this material from stoichiometry. The presence of oxygen vacancies induces a local charge redistribution, associated with the local lattice perturbation, and expansion of the equilibrium volume, in line with the experimental data.