Lv Yang-Yang, Zhou Yonghui, Xu Lu, Luo Yecheng, Zhang Yan-Yan, Cao Lin, Zhou Jian, Chen Y B, Yao Shu-Hua, Zhang Shan-Tao, Yang Zhaorong, Chen Yan-Feng
National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China.
Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China.
J Phys Condens Matter. 2021 Mar 10;33(10):105702. doi: 10.1088/1361-648X/abd11a.
High-pressure experiments usually expect a hydrostatic condition, in which the physical properties of materials can be easily understood by theoretical simulations. Unfortunately, non-hydrostatic effect is inevitable in experiments due to the solidification of the pressure transmitting media under high pressure. Resultantly, non-hydrostaticity affects the accuracy of the experimental data and sometimes even leads to false phenomena. Since the non-hydrostatic effect is extrinsic, it is quite hard to analyze quantitatively. Here, we have conducted high pressure experiments on the layered BiCuXO (X = S and Se) single crystals and quantitatively analyzed their pronounced non-hydrostatic effect by high throughput first-principles calculations and experimental Raman spectra. Our experiments find that the BiCuXO single crystals sustain the tetragonal structure up to 55 GPa (maximum pressure in our experiment). However, their pressure-dependent Raman shift and electric resistance show anomalous behaviors. Through optimization of thousands of crystal structures in the high throughput first-principles calculations, we have obtained the evolution of the lattice constants under external pressures, which clearly substantiates the non-hydrostatical pressure exerted in BiCuXO crystals. Our work indicates that the high throughput first-principles calculations could be a handy method to investigate the non-hydrostatic effect on the structural and electronic properties of materials in high pressure experiments.
高压实验通常期望达到静水压力条件，在此条件下，材料的物理性质能够通过理论模拟轻松理解。不幸的是，由于压力传递介质在高压下固化，非静水压力效应在实验中不可避免。结果，非静水压力会影响实验数据的准确性，有时甚至会导致出现假象。由于非静水压力效应是外在的，因此很难进行定量分析。在此，我们对层状BiCuXO（X = S和Se）单晶进行了高压实验，并通过高通量第一性原理计算和实验拉曼光谱对其显著的非静水压力效应进行了定量分析。我们的实验发现，BiCuXO单晶在高达55 GPa（我们实验中的最大压力）时仍保持四方结构。然而，它们的压力依赖拉曼位移和电阻呈现出异常行为。通过在高通量第一性原理计算中对数千个晶体结构进行优化，我们获得了外部压力下晶格常数的演变情况，这清楚地证实了施加在BiCuXO晶体中的非静水压力。我们的工作表明，高通量第一性原理计算可能是一种便捷的方法，用于研究高压实验中材料的结构和电子性质的非静水压力效应。
