Crystal structure and transporting properties of Bi 2 S 3 under high pressure: Experimental and theoretical studies
Crystal structure and transporting properties of Bi 2 S 3 under high pressure: Experimental and theoretical studies
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DOI：
10.1016/j.jallcom.2016.06.276
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发表时间：
2016-12
影响因子：
6.2
通讯作者：
Chunyu Li;Jinggeng Zhao;Qingyang Hu;Zhiguo Liu;Zhenhai Yu;Hao Yan
中科院分区：
文献类型：
--
作者：
Chunyu Li;Jinggeng Zhao;Qingyang Hu;Zhiguo Liu;Zhenhai Yu;Hao Yan
采用实验和理论相结合的方法，研究了辉铋矿（Bi_2S_3）的高压晶体结构和输运性质。实验结果表明，在实验压力范围内（55 GPa左右），Bi_2S_3的正交结构稳定存在。在压缩时，X射线衍射（XRD）图案由宽布拉格特征主导，并且似乎发生压力诱导的结构非晶化或无序。然而，通过分析在减压循环期间获得的XRD数据，我们认为，在高压下的宽布拉格衍射峰可能是由于非流体静力学条件或晶体结构缺陷。为了建立Bi2S3的结构变化与物理性质之间的关系，研究了Bi2S3在高压下的输运性质.随着压力的增加，电阻值在5GPa以下急剧下降，然后随着压力的进一步增加而缓慢下降。log（R）与压力的关系在5GPa附近有一个明显的拐点。根据文献报道，我们推测所观察到的电学变化是由压力诱导的二级等结构相变引起的。电阻随温度的变化表明，Bi2S3在20 GPa附近发生了压力诱导的半导体→金属相变。高压电阻测试结果表明，高压有利于提高热电性能。
The high-pressure crystal structure and transporting properties of bismuthinite (Bi2S3) have been studied with a combination of experimental and theoretical methods. The present experimental results show that the structure of orthorhombic Bi2S3stably exists in the experimental pressure range up to around 55 GPa. Upon compression, the X-Ray diffraction (XRD) patterns are dominated by broad Bragg features and seemingly pressure-induced structural amorphization or disorder occurs. However, by analyzing the XRD data obtained during the decompression cycle we suggest that the broad Bragg diffraction peaks under high pressure could be due to the nonhydrostatic conditions or crystal structural defects. To construct the correlation between the structural variation and the physical properties of Bi2S3, the transporting properties of Bi2S3were investigated under high pressure. With increasing pressure, the resistance value decreases sharply below 5 GPa and then decreases gently as the pressure further increasing. There is an obvious inflection point at about 5 GPa in the relationships of log (R) versus pressure. We speculate that the observed electrical variation is resulted from the pressure-induced second-order isostructural phase transition according to the reported literature. Temperature dependence of the resistance indicated that a pressure-induced semiconductor → metal transition in Bi2S3happens at around 20 GPa. The present high pressure resistance measurement indicated that high pressure could help to improve the thermoelectric properties.