Studies of A‐site Deficient (Gd0.6Sr0.4)1–sFe0.8Co0.2O3–δ Cathodes in SOFCs

Abstract A series of A‐site deficient Gd‐containing Fe‐Co‐based cathodes were synthesized using the glycine‐nitrate process. All the compounds consisted of two phases, i.e., a cubic and orthorhombic phase, as determined by powder X‐ray diffraction (XRD). The thermal expansion coefficient decreased with increasing A‐site deficiency, which could be because cobalt was expelled from the main phases. Likewise, the electrochemical activities of the Gd‐containing Fe‐Co‐based solid oxide fuel cell cathodes toward the reduction of oxygen ware improved by a factor of approximately 3 by making them A‐site deficient. The composition (Gd 0.6 Sr 0.4 ) 0.85 Fe 0.8 Co 0.2 O 3– δ showed the highest activity toward the reduction of oxygen among the five compounds. Electrochemical impedance spectroscopy estimated the area specific resistance as 5.77 Ω cm 2 at 600 °C. The electrochemical impedance spectroscopy measurements revealed three arcs for most of the compounds at the three temperatures where the measurements were performed.