학술논문
Mixed Valanced V 3+ ,V 2+ Phosphate Na 7 V 4 (PO 4) 6 : A Structural Analogue of Mineral Yurmarinite.
Document Type
Article
Author
Source
Subject
*X-ray absorption near edge structure
*HYDROTHERMAL synthesis
*MINERALS
*SODIUM phosphates
*VANADIUM compounds
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Language
ISSN
2075-163X
Abstract
Two sodium vanadium phosphates, synthetic analogues of the minerals kosnarite, Na3V2(PO4)3, and yurmarinite, Na7V4(PO4)6, were obtained by hydrothermal synthesis simulating a natural hydrothermal solution. While the Na3V2(PO4)3 phase belongs to the NASICON family and is well-known for its high-ionic conductivity, the new Na7V4(PO4)6 compound is a rare case of V2+-containing oxosalts, which are hard to prepare due to their instability in air. Here we report the crystal structure of heterovalent vanadium phosphate studied by single crystal X-ray diffraction, XANES spectroscopy, and topological ion migration modelling. A discussion of divalent vanadium compounds of both natural and synthetic origin is also given, with a review of the methods for their synthesis and a comparative analysis of V–O bond lengths. [ABSTRACT FROM AUTHOR]