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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >X-ray diffraction of silica gels made by sol-gel method under different conditions
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X-ray diffraction of silica gels made by sol-gel method under different conditions

机译：溶胶凝胶法制得的硅胶在不同条件下的X射线衍射

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Silica gels made from tetra-ethyl-orthosilicate (TEOS) under the basic condition and one made by two-step hydrolysis were studied by X-ray radial distribution function and correlation function analyses, and Si-29 NMR. X-ray scattering intensity, the medium range feature of the radial distribution function (RDF) curve and correlation function curve of silica gels was different from those of melt-derived silica. No difference in X-ray data was noted among the gels. The X-ray RDF data of the silica gels prepared under the basic condition and by the two-step by hydrolysis method were explained by using a medium-range-order (MRO) structure model consisting of fourfold siloxane ring units instead of sixfold siloxane rings which prevail in the melt-derived silica glass. It was estimated that the primary particles of the acid-catalyzed silica gels built up by fourfold rings were around 1.0 nm in size, and those of the base-catalyzed silica gels were a little larger. 40-50% of silicon atoms in the primary particle in the acid-catalyzed gels, and 60-70% of silicon in the base-catalyzed gels were bonded to other particles through forming Si-O-Si bonds. The remaining silicon atoms were terminated by forming Si-OH bonds which were considered to stabilize the fourfold siloxane ring unit in the gels. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 21]
机译：通过X射线径向分布函数和相关函数分析以及Si-29 NMR研究了在碱性条件下由原硅酸四乙酯（TEOS）制成的凝胶和由两步水解制成的硅胶。硅胶的X射线散射强度，径向分布函数（RDF）曲线的中程特征和相关函数曲线与熔融衍生的二氧化硅不同。凝胶之间未观察到X射线数据的差异。通过使用由四倍硅氧烷环单元而不是六倍硅氧烷环组成的中程（MRO）结构模型解释了在碱性条件下和通过两步水解法制备的硅胶的X射线RDF数据在熔融衍生的石英玻璃中普遍存在。据估计，由四重环形成的酸催化硅胶的初级颗粒的尺寸约为1.0nm，而碱催化硅胶的初级颗粒的尺寸稍大。酸催化凝胶中的一次颗粒中40-50％的硅原子和碱催化凝胶中的60-70％的硅通过形成Si-O-Si键与其他颗粒键合。其余的硅原子通过形成Si-OH键而终止，该键被认为可稳定凝胶中的四环硅氧烷环单元。 （C）1998 Elsevier Science B.V.保留所有权利。 [参考：21]

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