Defect chemistry and physical properties of Ln0.5Sr0.5FeO3 (Ln: La, Pr)

A defect chemical model for the behavior of acceptor and donor-doped LaFeO3 as a function of oxygen pressure is proposed. The nonstoichiometric deviation is calculated as a function of oxygen partial pressure, pO2, at different temperatures. The defect structure of complex oxides is described within the point defects approach. The results show that the conductivity is dependent on pO2 and temperature. Thermoelectric power values indicate clearly the nature of the dominant specie in charge transport. Stability regimes and compensation mechanisms at various oxygen partial pressures and temperatures are proposed. This model also examines the charge compensation mechanisms that dominate under the different regimes. From equilibrium constants, partial molar enthalpy and partial molar entropy of oxygen in Ln0.5Sr0.5Fe O3-δ (Ln: La, Pr) are estimated.