Novel proton-conducting hexagonal perovskites Ba7In6–xYxAl2O19 for solid oxide fuel cells

• Published in: Journal of alloys and compounds 2024-12, Vol.1008, Article 176582
• Main Authors: Andreev, Roman D., Animitsa, Irina E.
• Format: Article
• Language: English
• Subjects: Hexagonal perovskites; Proton conductors; Transport properties
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.176582

The solid solution Ba7In6–xYxAl2O19 (0≤x≤0.25) with a hexagonal perovskite-like structure was prepared by the solid-state route. The introduction of yttrium was accompanied by an increase in lattice parameters. The total conductivity as a function of pO2 and T was measured at different humidity. The partial conductivities were found by transport number measurements and were fitted based on the defect formation model. Oxygen-ion and proton conductivities were found to increase with Y3+ content as a result of an increase in cell volume and free volume, which was accompanied by a decrease in the activation energy of both oxygen-ion and proton conductivity. Oxygen-ion conductivity and proton conductivity dominated below 500 °C in dry (pH2O=3.5×10−5 atm) and in wet (pH2O=1.92×10−2 atm) conditions, respectively. Doping makes it possible to increase proton conductivity by an order of magnitude (500 °C) and significantly increase the proton transport numbers. The prepared phases exhibited excellent chemical stability during thermal treatment in carbon dioxide (pCO2=1 atm). [Display omitted] •New hexagonal perovskites with intergrowth structure.•Ba7In6–xYxAl2O19 were obtained.•Ba7In6–xYxAl2O19 showed chemical resistance to carbon dioxide at 600 °C.•Y3+ doping led to an increase in ion conductivities and ion transport numbers.•Ba7In6–xYxAl2O19 are predominantly proton conductors at temperatures below 500 °C.