Proton uptake in BSFMZZ triple-conducting perovskites

The proton uptake behavior of the BaySr1‑y(Fe0.75Mo0.25)1‑2xZrxZnxO3‑δ materials intended for application in solid oxide and protonic ceramic fuel and electrolysis cells (SOFCs/SOECs, PCFCs/PCECs) is extensively studied to elucidate the role of Ba, Zr, and Zn dopants in the formation and stabilization of protonic defects. Compared with the parent SrFe0.75Mo0.25O3‑δ composition (SFM), the modified compounds exhibit a pronounced enhancement in terms of proton uptake capabilities, with proton concentration at 250 °C changing from 0.05% for the base SFM, to 9.0% for the modified BaFe0.45Mo0.15Zn0.2Zr0.2O3‑δ material. The analysis shows that the main driving factors for this behavior are increased oxygen non‑stoichiometry associated with Zn incorporation, together with lattice expansion and increased overall basicity induced by Ba substitution. The values of ΔGhyd reported for the BaySr1‑y(Fe0.75Mo0.25)1‑2xZrxZnxO3‑δ series show a strong correlation with fundamental properties, such as electronegativity and total electrical conductivity, as has been reported for other triple‑conducting perovskites.