NaF-KF-AlF 3系统：K 2 NaAl 3 F 12三氟化物中的相变,Inorganic Chemistry

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NaF-KF-AlF ₃系统：K ₂ NaAl ₃ F ₁₂三氟化物中的相变
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2015-06-02 00:00:00 , DOI: 10.1021/acs.inorgchem.5b00772
Sergei D. Kirik ₁ , Yulia N. Zaitseva ₂ , Darya Yu. Leshok ₁ , Alexandr S. Samoilo ₁ , Petr S. Dubinin ₁ , Igor S. Yakimov ₁ , Dmitry A. Simakov ₃ , Alexandr O. Gusev ₃

Affiliation

已经研究了在K ₂ NaAl ₃ F ₁₂组成附近的NaF-KF-AlF ₃系统中的相形成。样品是通过在650°C下熔化起始组分而制备的。已经揭示了一个新相，它似乎是众所周知的K ₂ NaAl ₃ F ₁₂的低温形式。通过水热合成法得到的三元氟化物。高温形式在598°C时熔化，并在低于熔点约15度的狭窄温度范围内稳定。热分析，高温X射线衍射，IR光谱，X射线荧光和X射线粉末衍射的晶体结构分析已用于研究低温相的组成，晶体结构和热性质。晶体结构由[AlF ₆通过顶点连接的八面体。二维栅格具有特定的波状构型，其波长为11.88Å，振幅为0.46Å。相邻网格之间存在相对移动。由于此移动，网格之间的空间会发生变化。这种转变导致形成适合钾离子和钠离子的孔。讨论了层状波状结构的原因。结果表明，两种多晶型形式的阳离子占据顺序不同。

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NaF-KF-AlF3 System: Phase Transition in K2NaAl3F12 Ternary Fluoride

Phase formation in the NaF-KF-AlF₃ system, in the vicinity of the K₂NaAl₃F₁₂ composition, has been studied. The samples have been prepared by melting the starting components at 650 °C. A new phase has been revealed, which appeared to be a low-temperature form of the well-known K₂NaAl₃F₁₂ ternary fluoride obtained by the hydrothermal synthesis method. The high-temperature form melts at 598 °C and is stable in a narrow temperature region of about 15 deg below the melting point. Thermal analysis, high temperature X-ray diffraction, IR-spectroscopy, X-ray fluorescence, and X-ray powder diffraction crystal structure analysis have been applied to study the composition, crystal structure, and thermal properties of the low-temperature phase. The crystal structure consists of trigonal–hexagonal two-dimensional (2D) grids built from the [AlF₆] octahedra connected via vertices. The 2D grids have a specific wave-like conformation with a wavelength of 11.88 Å and an amplitude of 0.46 Å. There is a shift of the adjacent grids relative to each other. Because of this shift, the space between the grids changes. The shift leads to the formation of pores adapted to potassium and sodium ions. The reasons for the wave-like structure of layers are discussed. It is shown that the two polymorphic forms differ in the order of cation occupations.

更新日期：2015-06-02

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