Local structural changes during the disordered substitutional alloy transition in Bi2Te3 by high-pressure XAFS
Local structural changes during the disordered substitutional alloy transition in Bi2Te3 by high-pressure XAFS
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通过高压 XAFS 研究 Bi2Te3 无序替代合金转变过程中的局部结构变化
DOI：
10.1063/1.5042457
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发表时间：
2018-08
影响因子：
3.2
通讯作者：
Dongliang Chen
中科院分区：
文献类型：
--
作者：
Zhiying Guo;Hailiang Zhu;Juncai Dong;Quanjie Jia;Yu Gong;Yan Wang;Haijing Li;Pengfei An;Dongliang Yang;Yidong Zhao;Haiying Xing;Xiaodong Li;Dongliang Chen
A2 B3型三维拓扑绝缘体Bi 2 Te 3和Sb 2 Te 3在高压下会转变为无序的替位合金。然而，在Bi_2Te_3中，无序Bi-Te二元合金形成过程中Bi周围的γ → δ相变和局部结构变化仍然不清楚。在这里，高压X射线吸收精细结构（XAFS）结合高压X射线衍射已被用来探索在三个结构相变的Bi 2 Te 3的局部结构转变。BiL 3-X射线吸收近边结构（XANES）谱表明，δ-Bi 2 Te 3在γ → δ相变过程中出现了能量约为13465 eV的新吸收特征。通过改变团簇尺寸对XANES谱的模拟，我们证实了新的吸收峰来自体心立方结构中的中程有序。δ相的Bi L3-EXAFS结果表明，第三壳层中的Bi原子随着压力的增加而异常伸长，直至与收缩的Te壳层合并。我们的研究结果表明，无序置换合金通过有序的体心立方中间相的两步结构转变。
A2B3-type 3D topological insulators, Bi2Te3 and Sb2Te3, have been reported to transform into disordered substitutional alloys under high pressure. However, γ → δ phase transition and the local structure changes around Bi during the formation of the disordered Bi-Te binary alloy in Bi2Te3 still remain unclear. Here, high-pressure X-ray absorption fine structure (XAFS) combined with high-pressure X-ray diffraction has been used to explore the local structural transformations in the three structural phase transitions of Bi2Te3. The Bi L3-X-ray absorbing near edge structure (XANES) spectra of δ-Bi2Te3 clearly showed that a new absorption feature at energy of about 13 465 eV would emerge during the γ → δ phase transition. Through simulation of the XANES spectra by varying the cluster size, we confirmed that the new absorption peak arises from the medium-range order in bcc structure. The Bi L3-EXAFS results in δ phase reveal that the Bi atoms in the third shell exhibit abnormal elongations with pressure until merging with the shrinking Te shell. Our findings indicate a two-step structural transition of the disordered substitutional alloys via an ordered bcc intermediate phase.
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影响因子：
3.2
作者：
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DOI：
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期刊：
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Newville, M
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