Crystal structure of a new vanadium(IV) diphosphate: VP₂O₇, prepared by lithium extraction from LiVP₂O₇

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• 作者：Rousse ; Gwenaë ; lle ; Wurm ; Calin ; Morcrette ; Mathieu ; Rodriguez-Carvajal ; Juan ; Gaubicher ; Joë ; l ; et. al.
• 关键词：Vanadium diphosphate ; Lithium battery ; Chemical delithiation
• 刊名：The International Journal of Inorganic Materials
• 出版年：2001
• 期刊代码：40_14666049
• 类别：ms
• 出版时间：November, 2001
• 卷：3
• 期：7
• 页码：881-887
• 文件大小：1.01 M

摘要

A new vanadium(IV) diphosphate, VP₂O₇, was obtained by lithium extraction from LiVP₂O₇. The parent compound, LiVP₂O₇, is built on [P₂O₇] groups and [VO₆] octahedra and its structure has been confirmed by Synchrotron X-ray powder diffraction. The extraction of one lithium, both electrochemically or chemically, leads to VP₂O₇ which presents a totally different diffraction pattern diagram. The crystal structure of this new compound was determined from Synchrotron X-ray powder diffraction on the chemically prepared sample. The framework of LiVP₂O₇ is maintained upon lithium extraction, and VP₂O₇ crystallizes in space group P2₁. Compared to LiVP₂O₇, there is a very large cell distortion due to a modification of the shape of the tunnels that contained lithium ions along with an oxidation of the vanadium V^III to V^IV that induces shorter V–O bond lengths. The phase transformation from LiVP₂O₇ to VP₂O₇ is found to be displacive and not reconstructive.