Liquid-like cationic sub-lattice in copper selenide clusters.
Liquid-like cationic sub-lattice in copper selenide clusters.
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DOI：
10.1038/ncomms14514
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发表时间：
2017-02-20
影响因子：
16.6
通讯作者：
Jain PK
中科院分区：
文献类型：
--
作者：
White SL;Banerjee P;Jain PK
超离子固体的离子迁移率与液体或熔盐中的离子迁移率一样高，已被用作电池中的固态电解质、超级电容器和燃料电池中改进的热电材料和快离子导体。许多这些固体中的快离子传输是由在刚性阴离子子晶格内移动的无序、“液体状”阳离子子晶格支持的，通常在高温或高压下通过相变实现。在这里，我们表明，超小的硒化铜簇在环境条件下表现出无序的阳离子亚晶格，这与较大的纳米晶体不同，其中铜离子和空位形成类似于块状固体的有序超结构。这些簇表现出一种不寻常的阳离子亚晶格排列，其中作为阳离子迁移桥梁的八面体位点通过压缩应变而稳定。 Cu+ 亚晶格的室温液体性质与 Cu2Se 簇的主动可调等离子体特性相结合，使其适合用作快速电光开关。硒化铜仅在高温下才具有超离子性。在这里，作者发现了超小 Cu2Se 簇中的室温超离子行为，但不是以其较大或块状的形式，这是由于一种不寻常的液体状阳离子亚晶格，其中八面体位点通过尺寸依赖的压缩应变来稳定。
Super-ionic solids, which exhibit ion mobilities as high as those in liquids or molten salts, have been employed as solid-state electrolytes in batteries, improved thermoelectrics and fast-ion conductors in super-capacitors and fuel cells. Fast-ion transport in many of these solids is supported by a disordered, ‘liquid-like' sub-lattice of cations mobile within a rigid anionic sub-lattice, often achieved at high temperatures or pressures via a phase transition. Here we show that ultrasmall clusters of copper selenide exhibit a disordered cationic sub-lattice under ambient conditions unlike larger nanocrystals, where Cu+ ions and vacancies form an ordered super-structure similar to the bulk solid. The clusters exhibit an unusual cationic sub-lattice arrangement wherein octahedral sites, which serve as bridges for cation migration, are stabilized by compressive strain. The room-temperature liquid-like nature of the Cu+ sub-lattice combined with the actively tunable plasmonic properties of the Cu2Se clusters make them suitable as fast electro-optic switches. Copper selenide is super-ionic only at high temperatures. Here, the authors discover room temperature super-ionic behaviour in ultrasmall clusters of Cu2Se—but not in its larger or bulk forms—owing to an unusual liquid-like cationic sub-lattice, in which octahedral sites are stabilized by size-dependent compressive strain.