Ba-containing ferrites, Pr1–xBaxFeO3–δ, as symmetrical electrodes and their functional properties in both oxidizing and reducing atmospheres

Searching for suitable materials for symmetrical solid oxide fuel cells is an essential direction in modern high-temperature electrochemistry. One promising option for symmetrical electrode materials is a family of Fe-based complex oxides, which have high mixed ionic and electronic conductivity. This study focuses on the synthesis and thorough evaluation of the Pr1–xBaxFeO3–δ (x = 0.4, 0.5, 0.6) materials as symmetrical electrodes for proton ceramic electrochemical cells. The functional properties of these phases, both in powder and ceramic forms, are investigated for the first time under oxidizing and reducing conditions. The obtained results indicate that a low Ba-content is preferable for achieving high redox stability, low thermal expansion, and high conductivity of ferrite-based perovskites. However, Ba-enriched samples exhibit the lowest polarization resistance, particularly in reducing atmospheres. This may be due to the easier exsolution of Fe-metallic particles with high electrocatalytic activity. Therefore, a certain compromise needs to be achieved considering the obtained experimental data in a complex form. This work provides a basis for designing symmetrical electrodes by offering comprehensive information on the functional properties of ferrites in both oxidizing and reducing conditions.