A first-principles investigation of the effects of strain and Pd-doping on ion transfer in LSCF bulk of solid oxide cells

Abstract

Applied strain can be employed to tune ion migration properties in oxygen electrode bulk. Here migration properties of oxygen vacancy in Pd doped La1−xSrxCo1−yFeyO3−δ (LSCF) bulk (LSCFPd) were investigated with density functional theory under 3 % tensile and compressive strains. Formation energies of oxygen vacancy are reduced under tensile strain while they exhibit a nontrivial dependence as a function of compressive strain near Pd-doping sites. Migration barriers of oxygen vacancy in LSCF and LSCFPd bulks are also significantly reduced with tensile strain compared to that with non-strain. However, barriers near Pd-doping site increase greatly under compressive strain. The variation of oxygen vacancy formation and migration properties can be ascribed to the redistribution of atomic charges and local structural distortion caused by Pd-doping and applied strain. Results indicate that Pd-doping and application of tensile strain can significantly improve oxygen vacancy formation and migration properties.