Ba and Gd Doping Effect in (BaxSr1–x)0.95Gd0.05Co0.8Fe0.2O3–δ (x = 0.1–0.9) Cathode on the Phase Structure and Electrochemical Performance

Abstract In this study, Ba x Sr 1– x Co 0.8 Fe 0.2 O 3–δ (BSCF) doped with trace of Gd were studied for phase structures and properties about thermal expansion, electrical conductivity, and electrocatalytic activity. The solution range of barium in Ba x Sr 1– x Co 0.8 Fe 0.2 O 3–δ can be extended to 0.1 ≤ x ≤ 0.7 after the introduction of small amount of Gd 3+ ions (only for 5%) into the Ba/Sr‐site. The calculation results of the crystal structure and the crystal lattice energy show that the ratio of Ba/Sr and doping of Gd 3+ lead to increase the lattice parameter and the Co/Fe ionic average valence state in B‐site. Moreover, the ratio of Ba/Sr and doping of Gd 3+ were found to have significant impacts on the high‐temperature physical properties and electrochemical characteristics. All oxides exhibited decreases in the thermal expansion coefficient (TEC) and electrical conductivity with increasing Ba/Sr ratio. Barium insertion was found to change the area‐specific resistance (ASR) of porous (not dense) cathodes. An ASR values of 0.048, 0.072, 0.064, 0.121, and 0.059 Ω cm 2 under air condition were observed at 650 °C for BSGCF with x = 0.1, 0.2, 0.3, 0.5, and 0.7, respectively.