高达60 GPa的氟钙钛矿CsCdF3的高压结构研究:实验与理论相结合的研究
High pressure structural study of fluoro perovskite CsCdF3 upto 60 GPa: A combined experimental and theoretical study
摘要:
本文从理论和实验两方面研究了CsCdF_3在压力下的结构行为。使用同步辐射进行高压粉末X射线衍射实验,最大压力为60 GPa。立方$Pm\bar{3}m$晶体对称性在整个压力范围内持续存在。在局域密度近似和广义梯度近似下,采用全势能线性Muffin-tin轨道方法对交换效应和关联效应进行了理论计算。计算得到的平衡晶格常数、体弹性模量和弹性常数等基态性质与实验结果吻合较好。在环境条件下,CsCdF 3是一种间接间隙绝缘体,间隙在压力下增加。
英文摘要:
The structural behaviour of CsCdF3 under pressure is investigated by means of theory and experiment. High-pressure powder x-ray diffraction experiments were performed up to a maximum pressure of 60 GPa using synchrotron radiation. The cubic $Pm\bar{3}m$ crystal symmetry persists throughout this pressure range. Theoretical calculations were carried out using the full-potential linear muffin-tin orbital method within the local density approximation and the generalized gradient approximation for exchange and correlation effects. The calculated ground state properties -- the equilibrium lattice constant, bulk modulus and elastic constants -- are in good agreement with experimental results. Under ambient conditions, CsCdF3 is an indirect gap insulator with the gap increasing under pressure.
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