La₂Mo₂O₉ is acknowledged as an exceptional oxide ion conductor. It undergoes a reversible phase transition around 580 °C from the nonconductive low-temperature monoclinic α-La₂Mo₂O₉ phase to the highly conductive high-temperature cubic β-La₂Mo₂O₉ phase. In addition, La₂Mo₂O₉ demonstrates complex chemistry under reducing conditions. This study reports, for the first time, the stabilization at ambient temperature of a novel cubic phase through a topotactic reduction of α-La₂Mo₂O₉ employing CaH₂. This phase contains approximately ∼3 atom % oxygen vacancies relative to the nominal composition (La₂Mo₂O_8.68(1)). The cubic symmetry is associated with a static distribution of these vacancies, in contrast to the dynamic distribution observed in the high-temperature cubic β-La₂Mo₂O₉ phase reported previously. Additionally, the material exhibits mixed-ion-electronic conduction, which expands its potential use in applications requiring both ionic and electronic transport.

中文翻译：

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拓扑还原诱导的 β-La2Mo2O8.68 相稳定化：结构、静态氧紊乱和电学性质


La₂Mo₂O₉ 被公认为一种特殊的氧化物离子导体。它在 580 °C 左右从非导电低温单斜相 α-La₂Mo₂O₉ 相转变为高导电高温立方 β-La₂Mo₂O₉ 相。此外，La₂Mo₂O₉ 在还原条件下表现出复杂的化学性质。本研究首次报道了通过使用 CaH₂ 拓扑定向还原 α-La₂Mo₂O₉ 在环境温度下稳定新型立方相。相对于标称组成 （La₂Mo₂O_8.68（1）），该相包含大约 ∼3 原子 % 的氧空位。立方对称性与这些空位的静态分布有关，这与之前报道的高温立方 β-La₂Mo₂O₉ 相中观察到的动态分布相反。此外，该材料表现出混合离子-电子传导，这扩大了其在需要离子和电子传输的应用中的潜在用途。