Effects of the starting material and hydrothermal treatment conditions on the crystallization of ultrafine silica
Effects of the starting material and hydrothermal treatment conditions on the crystallization of ultrafine silica
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DOI：
10.1023/a:1014714631576
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发表时间：
2002-03-01
影响因子：
0.8
通讯作者：
Gusarov, VV
中科院分区：
文献类型：
--
作者：
Korytkova, EN;Chepik, LF;Gusarov, VV
研究了原料和水热结晶条件对纳米二氧化硅粉体物相组成和粒径的影响。在250-500度的温度范围和高达100 MPa的压力下，水热处理水和NaF和NaOH水溶液中的硅胶、干凝胶和气凝胶，会导致材料逐渐脱水和致密化，同时形成结晶SiO2品种，如或多或少有序的蛋白石硅、方英石、keatite和石英。这些转变的程度和速度，以及结晶相的粒度，取决于起始材料和工艺参数：温度、压力、持续时间和环境。制备粒径为20 ~ 35 nm纳米晶二氧化硅的最佳前驱体是在250 ~ 300℃、100 MPa的水中处理过的硅胶和悬浮体。
The effects of the starting material and hydrothermal crystallization conditions on the phase composition and particle size of the resulting nanocrystalline silica powders were studied. Hydrothermal treatment of silica gels, xerogels, and Aerosils in water and aqueous NaF and NaOH solutions at temperatures in the range 250-500degreesC and pressures of up to 100 MPa causes gradual dehydration and densification of the materials, accompanied by the formation of crystalline SiO2 varieties, such as more or less ordered opaline silicas, cristobalite, keatite, and quartz. The extent and rate of these transformations, as well as the particle size of the crystallizing phases, depend on the starting material and the process parameters: temperature, pressure, duration, and environment. The best precursors to nanocrystalline silica with a particle size of 20-35 nm are silica gels and Aerosils treated in water at 250-300degreesC and 100 MPa.