Efficient stabilization of cubic perovskite SrCoO3−δ by B-site low concentration scandium doping combined with sol–gel synthesis

SrCoO3−δ is a material with multiple phase structures. The influence of Sc3+ doping in the B-site of SrCoO3−δ on its lattice structure/phase stability, electrical conductivity, and cathode performance for intermediate-temperature solid oxide fuel cells (IT-SOFCs) was investigated by X-ray diffraction, four-probe dc conductivity and impedance spectroscopy measurements, respectively. The introduction of large-size Sc3+ (0.745 Å) cation together with the sol–gel synthesis technique, led to a substantial stabilization of the cubic phase of SrCoO3−δ—even at a Sc3+ doping amount as low as 5 mol%. Such stabilization resulted in a sharp increase in the electrical conductivity of the material, which was found to be p-type in nature. A maximum electrical conductivity and favourable cubic phase stability of the material was reached at the Sc3+ doping concentration of 5–10 mol%. A further increase of Sc3+ doping, however, lowered the electrical conductivity due to the blocking effect of Sc3+ for the electron conduction. An area specific resistance (ASR) as low as 0.25 Ωcm2 was reached at 600 °C for SrSc0.1Co0.9O3−δ as a cathode material based on Sm0.15Ce0.85O1.925 electrolyte.