Crystal structure, polymorphism, and properties of the new vanadyl phosphate Na4VO(PO4)(2)статья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The new vanadyl phosphate Na4VO(PO4)(2) was synthesized and investigated by X-ray powder and single-crystal diffraction, high-temperature X-ray diffraction, electron diffraction, high-resolution electron microscopy, thermal analysis, magnetic susceptibility, and conductivity measurements. The compound undergoes a reversible phase transition at about 200 degreesC. The crystal structure of low-temperature beta-Na4VO(PO4)(2) was solved using X-ray single-crystal data. This phase has an orthorhombic unit cell with lattice parameters a = 16.0068(12) Angstrom, b = 14.5129(8) Angstrom, c = 7.0231(5) Angstrom, S.G. Pbca, and Z = 8. The crystal structure of beta-Na4-VO(PO4)(2) is built by isolated chains formed by corner-shared V4+O6 octahedra linked additionally via corners by two PO4 tetrahedra. All chains in the structure are equivalent. Na cations are located between the chains in an ordered manner. High-temperature alpha-Na4VO(PO4)(2) also has.an orthorhombic cell with lattice parameters a = 15.595(l) Angstrom, b = 14.651(2) Angstrom, c = 7.0262(6) Angstrom, S.G. Ibam, and Z = 8. Electron diffraction study revealed an existence of various structural transformations occurring in situ in the transmission electron microscope. In both alpha- and beta-modifications, the susceptibility follows a Curie-Weiss law with a very small Curie-Weiss temperature, indicating a very weak magnetic exchange among the V4+ ions.