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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 >The arrangement of fractal clusters dependent on the pH value in silica gels from sodium silicate solutions
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The arrangement of fractal clusters dependent on the pH value in silica gels from sodium silicate solutions

机译：分形簇的排列取决于硅酸钠溶液中硅胶的pH值

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Structural features and thus, optical transparency of silica hydro- and aerogels from sodium silicate solution strongly depend on the preparation parameters. This study is focused on the effect of pH, for values higher than the isoelectric point of silica acid (pH similar to 2). Previous studies have presented SAXS data characterizing the primary particles and fractal properties in silica gels from a sodium silicate solution. This study presents an analysis focusing on the structural units > 50 nm, which is the relevant structure for the process of gelation and for optical transparency. UV-vis-NIR spectra revealed that hydrogel transmission increases with rising pH and decreases with the fraction of SiO2. Scanning electron microscopy (SEM) analyses of the inner structure of the supercritical dried gels showed that the mean cluster size along with the deviation dropped substantially with rising pH. An equation which agrees with the experimental results and describes the correlation between cluster size, fractal dimension, and packing index in mass fractal cluster packages is provided. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 15]
机译：从硅酸钠溶液获得的二氧化硅水凝胶和气凝胶的结构特征以及由此的光学透明度在很大程度上取决于制备参数。这项研究的重点是pH的影响，其值高于硅酸的等电点（pH接近2）。先前的研究已经提出了SAXS数据，这些数据表征了硅酸钠溶液中硅胶的主要颗粒和分形特性。这项研究针对> 50 nm的结构单元进行了分析，该结构单元是凝胶化过程和光学透明性的相关结构。 UV-vis-NIR光谱表明，水凝胶透过率随pH升高而增加，随SiO2分数而降低。扫描电子显微镜（SEM）对超临界干燥凝胶内部结构的分析表明，随着pH的升高，平均簇尺寸及其偏差大大降低。提供了一个与实验结果相符的方程，该方程描述了质量分形簇包装中簇尺寸，分形维数和堆积指数之间的相关性。 （C）2001 Elsevier Science B.V.保留所有权利。 [参考：15]

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