论文标题
多功能CRVO4的高压表征
High-pressure characterization of multifunctional CrVO4
论文作者
论文摘要
通过X射线衍射，拉曼光谱，光吸收，电阻率测量和从头开始计算，研究了CRVO4在压缩下的结构稳定性和物理性能。高压X射线衍射和拉曼测量结果表明，CRVO4经历了从环境压力正压正压cRVO4型结构（CMCM空间组，III期）到高压单轨道单斜型CRVO4-V阶段的相变，这是Wolframite结构。以前在钒酸盐中也观察到了这种相变（CRVO4型 - wolframite）。据报道，两相的晶体结构和单位细胞参数，拉曼活性模式，电阻率和电子带隙中的压力依赖性。钒原子在Wolframite相中是第六倍，这与相变的体积崩溃有关。此外，我们还观察到声子频谱的急剧变化，带隙的滴滴以及电阻率的急剧下降。所有观察到的现象都在第一原理计算的帮助下进行了解释。
The structural stability and physical properties of CrVO4 under compression were studied by X-ray diffraction, Raman spectroscopy, optical absorption, resistivity measurements, and ab initio calculations up to 10 GPa. High-pressure X-ray diffraction and Raman measurements show that CrVO4 undergoes a phase transition from the ambient pressure orthorhombic CrVO4-type structure (Cmcm space group, phase III) to the high-pressure monoclinic CrVO4-V phase, which is isomorphic to the wolframite structure. Such a phase transition (CrVO4-type - wolframite), driven by pressure, also was previously observed in indium vanadate. The crystal structure of both phases and the pressure dependence in unit-cell parameters, Raman-active modes, resistivity, and electronic band gap, is reported. Vanadium atoms are sixth-fold coordinated in the wolframite phase, which is related to the collapse in the volume at the phase transition. Besides, we also observed drastic changes in the phonon spectrum, a drop of the band-gap, and a sharp decrease of resistivity. All the observed phenomena are explained with the help of first-principles calculations.
