Synthesis and Structure Determination of CaSi1/3B2/3O8/3: A New Calcium Borosilicate

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• 作者：Emmanuel V茅ron ; Mounesha N. Garaga ; Denis Pelloquin ; Sylvian Cadars ; Matthew Suchomel ; Emmanuelle Suard ; Dominique Massiot ; Val茅rie Montouillout ; Guy Matzen ; Mathieu Allix
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：April 15, 2013
• 年：2013
• 卷：52
• 期：8
• 页码：4250-4258
• 全文大小：532K
• 年卷期：v.52,no.8(April 15, 2013)
• ISSN：1520-510X

文摘

This article reports on the identification, synthesis, and in-situ structure determination of a new crystalline calcium borosilicate compound of composition CaSi_1/3B_2/3O_8/3. Synthesis was carried out by complete crystallization on annealing from a corresponding glassy composition in the widely studied CaO鈥揝iO₂鈥揃₂O₃ ternary system. The crystallographic structure was determined ab initio using electron diffraction information and the charge flipping algorithm performed on synchrotron and neutron powder diffraction data collected in situ at high temperature. CaSi_1/3B_2/3O_8/3 is found to crystallize in the Pna2₁ (no. 33) orthorhombic space group, with a = 12.1025(4) 脜, b = 5.2676(1) 脜, c = 3.7132(1) 脜, and V = 236.71(1) 脜³ at 650 掳C. Solid-state ²⁹Si and ¹¹B NMR experiments have confirmed the existence of finite chains along the c axis, formed by corner-sharing SiO₄ tetrahedra and BO₃ units. Silicon and boron species share a crystallographic site, and the Si/B distribution induces different possible arrangements of the chains which are discussed in light of DFT calculations. At room temperature, the existence of a superstructure, resulting from the ordering within nanoscale domains, was explored by transmission electron microscopy.