Oxide ion and proton conductors, which exhibit high conductivity at intermediate temperature, are necessary to improve the performance of ceramic fuel cells. The crystal structure plays a pivotal role in defining the ionic conduction properties, and the discovery of new materials is a challenging research focus. Here, we show that the undoped hexagonal perovskite Ba7Nb4MoO20 supports pure ionic conduction with high proton and oxide ion conductivity at 510 °C (the bulk conductivity is 4.0 mS cm−1), and hence is an exceptional candidate for application as a dual-ion solid electrolyte in a ceramic fuel cell that will combine the advantages of both oxide ion and proton-conducting electrolytes. Ba7Nb4MoO20 also showcases excellent chemical and electrical stability. Hexagonal perovskites form an important new family of materials for obtaining novel ionic conductors with potential applications in a range of energy-related technologies.
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This research was supported by the Leverhulme trust and EPSRC (MISE). We also acknowledge STFC-GB for provision of beamtime at the Institut Laue Langevin.
The authors declare that they have no competing interests.
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Fop, S., McCombie, K.S., Wildman, E.J. et al. High oxide ion and proton conductivity in a disordered hexagonal perovskite. Nat. Mater. 19, 752–757 (2020). https://doi.org/10.1038/s41563-020-0629-4
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