Sánchez-Martín Josu, Bouvier Pierre, Garbarino Gaston, Gallego-Parra Samuel, Isnard Olivier, Rodríguez-Hernández Plácida, Muñoz Alfonso, Errandonea Daniel, Pellicer-Porres Julio
Departamento de Física Aplicada-ICMUV, Universidad de Valencia, Dr. Moliner 50, Burjassot, Valencia 46100, Spain.
Université Grenoble Alpes, CNRS, Institut Néel, 25 rue des Martyrs, Grenoble 38042, BP166X, France.
J Phys Chem C Nanomater Interfaces. 2025 May 26;129(22):10364-10374. doi: 10.1021/acs.jpcc.5c02341. eCollection 2025 Jun 5.
The application of high pressure to orthorhombic columbite CoVO resulted in two phase transitions, characterized by single-crystal X-ray diffraction (XRD) and Raman spectroscopy up to 54.9(1) GPa. The first phase transition, at 20.0(1) GPa, is isostructural, preserving the space group () but implies a sudden volume reduction (4.7%) and a symmetrization of VO octahedra, as well as a group shift of the vibrational modes toward higher wavenumbers. The named columbite-II structure remains stable up to 45.6(1) GPa. Beyond this pressure, a different monoclinic polymorph (space group 2/) was deduced from the high-quality diffraction data. The two observed phase transitions are reversible, but below 4.9(3) GPa, the sample mainly transforms into the previously known brannerite polymorph. The anisotropic compressibility of the lattice axis and the Birch-Murnaghan equation of state were obtained from the XRD analysis. Our experimental results are supported by density functional theory calculations.
对正交晶系铌钽铁矿CoVO施加高压导致了两个相变，通过单晶X射线衍射（XRD）和拉曼光谱对高达54.9(1) GPa的压力范围进行了表征。第一次相变发生在20.0(1) GPa，是同构的，保持了空间群（），但意味着体积突然减小（4.7%）以及VO八面体的对称化，同时振动模式向更高波数发生了群位移。命名为铌钽铁矿-II的结构在高达45.6(1) GPa时保持稳定。超过这个压力后，从高质量衍射数据推断出一种不同的单斜多晶型（空间群2/）。观察到的这两个相变是可逆的，但在4.9(3) GPa以下，样品主要转变为先前已知的钛铀矿多晶型。通过XRD分析获得了晶格轴的各向异性压缩性和Birch-Murnaghan状态方程。我们的实验结果得到了密度泛函理论计算的支持。
