Synthesis of oxyanion-doped barium strontium cobalt ferrites: Stabilization of the cubic perovskite and enhancement in conductivity

In this paper we demonstrate the successful incorporation of oxyanions (borate, phosphate) into Ba1−ySryCo0.8Fe0.2O3−δ (BSCF) cathode materials. For low levels of dopant, a small enhancement in the conductivity was observed; e.g. 31.6, 34.4 and 35.9 S cm−1 for Ba0.33Sr0.67Co0.8Fe0.2O3−δ, Ba0.33Sr0.67Co0.76Fe0.19B0.05O3−δ and Ba0.33Sr0.67Co0.76Fe0.19P0.05O3−δ, respectively, at 700 °C. Most significantly, oxyanion doping was shown to improve the stability of the cubic form of BSCF at intermediate temperatures (especially for P-doping), helping to prevent the transition to a hexagonal cell, and maintaining its excellent electrical properties. The work shows the potential of oxyanion doping strategies to modify the performance of SOFC cathode materials.

► BaySr1−yCo0.8Fe0.2O3−δ samples have been successfully doped with borate and phosphate.
► For the B,P-doped samples there is a small enhancement in the electronic conductivity.
► Doping stabilizes the cubic form of BSCF at intermediate temperatures for long term experiments.
► The electrical properties for the P-doped samples remain unaltered after the annealing studies.