The perovskite crystal structure with nominal composition ABX₃ offers a very flexible framework for sodium halide ionic conductors, an aspect not well defined in the current literature. This structure can accommodate a variety of sizes and oxidation states of cations, as well as different contents of cation vacancies. Different studies have shown that substitution of trivalent by tetravalent cations in the structure of some halides ‘double’ perovskites significantly improve their ionic conductivity, which can be explained by the creation of cation vacancies in the B-sites. The understanding of the structure opens the possibility to create cation vacancies, not only in the B-sites but also in the A-sites, by the replacement of the trivalent cations by pentavalent cations and to study their impact on the ionic transport of sodium halide materials. In this work, we show a study of the Na_3−2xIn(III)_1−xTa(V)_xCl₆ system with respect to their structure, microstructure, and ionic transport properties, demonstrating the coupling among these three aspects. This work aims to provide a detailed description of the current halide ionic conductors in the framework of the perovskite structure. By fully describing sodium ion conducting halides as perovskites, we hope to offer a reliable guidance to design improved solid-electrolyte materials.

中文翻译：

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晶体结构和微观结构如何影响卤化物钙钛矿中的钠离子电导率


具有标称成分 ABX₃ 的钙钛矿晶体结构为卤化钠离子导体提供了一个非常灵活的框架，这是当前文献中没有明确定义的方面。这种结构可以适应各种大小和氧化态的阳离子，以及不同含量的阳离子空位。不同的研究表明，在一些卤化物“双”钙钛矿的结构中用四价阳离子取代三价阳离子显着提高了它们的离子电导率，这可以通过在 B 位点产生阳离子空位来解释。对结构的理解为不仅在 B 位点而且在 A 位点创造阳离子空位提供了可能性，通过用五价阳离子取代三价阳离子并研究它们对卤化钠材料的离子传输的影响。在这项工作中，我们展示了对 Na_3-2xIn（III）_1-xTa（V）_xCl₆ 系统的结构、微观结构和离子传输特性的研究，证明了这三个方面之间的耦合。这项工作旨在提供钙钛矿结构框架中当前卤化物离子导体的详细描述。通过将钠离子导电卤化物完全描述为钙钛矿，我们希望为设计改进的固体电解质材料提供可靠的指导。