Hydride Conductivity in an Anion-Ordered Fluorite Structure LnHO with an Enlarged Bottleneck
Hydride Conductivity in an Anion-Ordered Fluorite Structure LnHO with an Enlarged Bottleneck
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DOI：
10.1021/acs.chemmater.9b01968
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发表时间：
2019-09-24
影响因子：
8.6
通讯作者：
Kageyama, Hiroshi
中科院分区：
文献类型：
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作者：
Ubukata, Hiroki;Broux, Thibault;Kageyama, Hiroshi
我们使用高压下制备的样品报告了萤石型 LnHO 氢氧化物（Ln = 镧系元素）的氢化物 (H-) 电导率。研究发现，尽管其组成为“化学计量”，阴离子有序相（Ln = La，Nd）仍表现出氢化物电导率（例如，300℃下NdH2O的电导率为2.3 x 10(-5) S cm(-1)），而阴离子无序相（Ln = Gd，Er）是离子绝缘体。系统结构分析结合计算计算揭示了间接填隙机制，其中H-阴离子通过阴离子级数扩大的三角形Ln(3)瓶颈在四面体和八面体位点之间迁移，临界瓶颈半径为1.18埃。这项研究可以为氢氧化合物和更常见的混合阴离子化合物的合适阴离子扩散途径的设计和控制提供一般指导。
We report on the hydride (H-) conductivity in fluorite-type LnHO oxyhydrides (Ln = lanthanide) using samples prepared under high pressure. It is found that, despite its "stoichiometric" composition, the anion-ordered phase (Ln = La, Nd) exhibits hydride conductivity (e.g., 2.3 x 10(-5) S cm(-1) for NdHO at 300 degrees C), while the anion-disordered one (Ln = Gd, Er) is an ionic insulator. The systematic structural analysis combined with computational calculations has revealed the indirect interstitial mechanism, where H- anions migrate between the tetrahedral and octahedral sites through a triangular Ln(3) bottleneck expanded by the anion order, with a critical bottleneck radius of 1.18 angstrom. This study may offer a general guide for the design and control of suitable anion diffusion pathways for oxyhydrides and more generally mixed-anion compounds.