Atomistic modelling showed that a key factor affecting the p(O2) dependencies of point defect chemical potentials in perovskite-type La0.3Sr0.7Fe1−xM′xO3−δ (M′ = Ga, Al; x = 0–0.4) under oxidizing conditions, relates to the coulombic repulsion between O vacancies and/or electron holes. The configurations of A- and B-site cations with stable oxidation states had no essential influence on energetics of the mobile charge carriers, whereas the electrons formed due to Fe disproportionation were expected to form defect pair clusters with O vacancies. These results were used to develop thermodynamic models, adequately describing the p(O2)-T-δ diagrams of La0.3Sr0.7Fe(M′)O3−δ determined by the coulometric titration technique at 923 to 1223K under O partial pressures ranging from 10−5 to 0.5atm. The thermodynamic functions governing the O intercalation process were found to be independent of the defect concentration. Doping with Al and Ga led to increasing O deficiency and induces substantial changes in the behavior of Fe cations, increasing the

tendencies to disproportionation and hole localization. Despite similar O non-stoichiometry in the Al- and Ga-substituted ferrites at a given dopant content, the latter tendency was more pronounced in the case of aluminum-containing perovskites.

Defect Interactions in La0.3Sr0.7Fe(M′)O3−δ (M′ = Al, Ga) Perovskites - Atomistic Simulations and Analysis of p(O2)-T-δ Diagrams. E.N.Naumovich, M.V.Patrakeev, V.V.Kharton, M.S.Islam, A.A.Yaremchenko, J.R.Frade, F.M.B.Marques: Solid State Ionics, 2006, 177[5-6], 457-70