High-Temperature, High-Pressure Hydrothermal Synthesis, Crystal Structure, and Solid-State NMR Spectroscopy of Cs2(UO2)(Si2O6) and Variable-Temperature Powd

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• 作者：Chih-Shan Chen ; Ray-Kuang Chiang ; Hsien-Ming Kao ; and Kwang-Hwa Lii
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：May 30, 2005
• 年：2005
• 卷：44
• 期：11
• 页码：3914 - 3918
• 全文大小：139K
• 年卷期：v.44,no.11(May 30, 2005)
• ISSN：1520-510X

文摘

A new uranium(VI) silicate, Cs₂(UO₂)(Si₂O₆), has been synthesized by a high-temperature, high-pressure hydrothermalmethod and characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. It crystallizes in theorthorhombic space group Ibca (No. 73) with a = 15.137(1) Å, b = 15.295(1) Å, c = 16.401(1) Å, and Z = 16.Its structure consists of corrugated achter single chains of silicate tetrahedra extending along the c axis linkedtogether via corner-sharing by UO₆ tetragonal bipyramids to form a 3-D framework which delimits 8- and 6-ringchannels. The Cs⁺ cations are located in the channels or at sites between channels. The ²⁹Si and ¹³³Cs MAS NMRspectra are consistent with the crystal structure as determined from X-ray diffraction, and the resonances in thespectra are assigned. Variable-temperature in situ powder X-ray diffraction study of the hydrate Cs₂(UO₂)(Si₂O₆)·0.5H₂O indicates that the framework structure is stable up to 800 C and transforms to the structure of the titlecompound at 900 C. A comparison of related uranyl silicate structures is made.