Synthesis of nanostructured BSCF by oxalate co-precipitation – As potential cathode material for solid oxide fuels cells

BaxSr1−xCoyFe1−yO3 (BSCF) cathode material for solid oxide fuel cells (SOFC) was synthesized in nanocrystalline form by a novel chemical alloying approach. Thermodynamic modeling has been performed using Medusa software for obtaining the optimum conditions for the fabrication of a precursor with the desired composition. Precursor powder was then calcined and annealed to produce the final mixed oxide BSCF composition. The thermal properties, phase constituents, microstructure and elemental analysis of the samples were characterized by TGA, XRD, SEM and EDS techniques respectively. Spark Plasma Sintering (SPS) has been used at 1080 °C and under 50 MPa pressure to obtain the pellets of BSCF with preserved nanostructure and rather high compaction density for electrical conductivity measurements. The results show that the powders have cubic perovskite-type structure with a high homogeneity. Finer resultant powder, compared to earlier reports, and SPS sintered BSCF with nanosized grains exhibited a significantly higher electrical conductivity up to 900 °C. Specific conductivity values have been measured in air and N2 and the maximum of 63 S cm−1 at 430 °C in air and 25 S cm−1 at 375 °C in N2 correspondingly show twice as much as conventional BSCF implying a high pledge for nano-BSCF as cathode material in intermediate-temperature SOFC. This is due to the lower interfacial resistance of preserved nanograins by the use of SPS sintering. Presented co-precipitation method is easy to handle and has a high promise to synthesize BSCF at large-scale for IT-SOFCs.