中间相
小角X射线散射
成核
同步加速器
散射
衍射
相(物质)
材料科学
结晶学
介孔二氧化硅
介孔材料
同步辐射
X射线
胶束
六角相
X射线晶体学
化学工程
化学
六方晶系
物理化学
光学
催化作用
有机化学
物理
工程类
水溶液
作者
Katarina Flodström,Cilâine Verônica Teixeira,Heinz Amenitsch,Viveka Alfredsson,Mika Lindén
出处
期刊:Langmuir
[American Chemical Society]
日期:2004-05-07
卷期号:20 (12): 4885-4891
被引量:148
摘要
The initial stages of the formation of SBA-15 have been studied by in situ SAXS/XRD using synchrotron radiation. Modeling of both the diffuse scattering and the X-ray diffraction patterns obtained at different stages of the reaction results in a detailed description of the different reaction steps. The first step in the formation is the liquid-liquid phase separation of spherical P123-silicate hybrid micelles after which nucleation and growth of the 2D hexagonal phase occurs. Two-dimensional electron density maps calculated on the basis of the intensities of the Bragg reflections suggest that changes in the degree of intermicellar condensation are responsible for the time-dependent observations. The silica source (alkoxysilanes) may be partially unhydrolyzed long after formation of the hexagonal structure, since the kinetics of the mesophase evolution is notably slower when TEOS is used as the silica precursor as compared to TMOS. The results obtained for SBA-15 are compared with other published data on the formation ofSBA-15 and of the smaller pore MCM-41 materials.
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