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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Spatial distribution of rare-earth ions in Se-based chalcogenide glasses with or without Ga
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Spatial distribution of rare-earth ions in Se-based chalcogenide glasses with or without Ga

机译：含或不含Ga的硒基硫族化物玻璃中稀土离子的空间分布

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摘要

Measured lifetime of the (3F3, 3F4) level of Pr3+ ions doped in representative Se-based chalcogenide Ge–Sb–Se glasses peaked at the mean coordination number of 2.67, indicating that inter-ionic distance between Pr3+ dopants became maximized on the average at such particular host compositions. However, this phenomenon was not observed when Ga was further introduced. It has been verified from Ga K-edge EXAFS spectroscopic analysis that a Ga atom has four Se atoms as its nearest neighbors in the Ge–Sb–Se glasses doped with Pr. The Ga–Se bonds are less covalent than other heteropolar chemical bonds, and thereby positively ionized rare-earth elements would be located preferentially next to the GaSe4 units, acting as charge compensators or network modifiers. We presume that there is a negligible structural and chemical correlation between a rare-earth ion and its next-nearest neighbors on their sites in the typical covalent chalcogenide glasses without Ga, and as a result spatial distribution of rare-earth ions would depend on changes of the free volume accompanied with the structural phase transitions on a medium-range scale from two-dimensional layers to three-dimensional networks. In selenide glasses with Ga, however, the empirical connection disappears due to the structural correlation between rare-earth ions and the GaSe4 tetrahedra.
机译：在代表性的基于Se的硫族化物Ge–Sb–Se玻璃中掺杂的Pr3 +离子的（3F3，3F4）水平的实测寿命达到2.67的平均配位数，表明Pr3 +掺杂剂之间的离子间距离平均达到最大值这样的特定宿主组合物。然而，当进一步引入Ga时，未观察到该现象。通过Ga K-edge EXAFS光谱分析已证实，在掺有Pr的Ge-Sb-Se玻璃中，Ga原子具有四个Se原子作为其最近邻。 Ga-Se键的共价比其他杂极化学键低，因此，正离子化的稀土元素将优先位于GaSe4单元旁边，充当电荷补偿剂或网络修饰剂。我们假设，在没有Ga的典型共价硫属化物玻璃中，稀土离子与其次近邻之间的结构和化学相关关系可忽略不计，因此，稀土离子的空间分布取决于变化自由体积的变化伴随着结构范围从二维层到三维网络的中等范围的过渡。然而，在具有Ga的硒化物玻璃中，由于稀土离子与GaSe4四面体之间的结构相关性，经验联系消失了。

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