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.

中文翻译：

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无序六方钙钛矿中的高氧化物离子和质子传导性。

为了提高陶瓷燃料电池的性能，在中等温度下具有高导电性的氧化物离子和质子导体是必需的。晶体结构在定义离子传导特性中起着关键作用，而新材料的发现是具有挑战性的研究重点。在这里，我们显示出未掺杂的六方钙钛矿Ba7Nb4MoO20在510°C（整体电导率为4.0 mS cm-1）下支持具有高质子和氧化物离子电导率的纯离子导电，因此是应用为双离子的优异候选者陶瓷燃料电池中的固体电解质，将结合氧化物离子和质子传导电解质的优点。Ba7Nb4MoO20还具有出色的化学和电稳定性。