The substitution of Ca²⁺ and La³⁺ ions at A-site and the addition of Ca²⁺, Cu²⁺ and Zn²⁺ ions in the structure of Ba₀.₅Sr₀.₅Co₀.₈Fe₀.₂O₃-δ (BSCF) were successfully performed by the modified citrate method. The characterization by XRD and SEM demonstrated that all samples showed the single phase of cubic ABO₃ perovskite oxide however the BSCF substituted by Ca²⁺ ion at 40 mol% in A-site still presenting small impurity phase of CaO. The electrical conductivity was increased with the increasing substitution of Ca²⁺ ion and the maximum electrical conductivity was 96 S.cm⁻¹ at 650 ℃ for the BSCCF (Ca 30 mol%). The results of O2-TPD indicated the substitution of Ca²⁺ ion in A-site showed the increasing of oxygen desorption. Furthermore, the substitution of Ca²⁺ ion in La3+ ion of the BSLCF affected the decreasing of electrical conductivity and the maximum conductivity achieved from the BSLCF was 353 S.cm-1 at 350 ℃. In addition, the electrical conductivity of the BSLCFCa₀.₀₁ showed the maximum value of 593 S.cm⁻¹ at 350 ℃ and the addition of Cu²⁺ and Zn²⁺ ions not had the affected on the electrical conductivity of materials.
