摘要
通过控制反应合成温度，合成了具有六方和立方相结构的介孔氧化硅材料，并借助ＸＲＤ，ＴＧＡ，ＨＲＥＭ 和Ｎ２吸附－ 脱附等手段对材料性能进行了表征．ＸＲＤ结果显示，在合成温度低于７５ ℃时，合成的材料具有不稳定的六方结构；而较高温度下则可促使六方结构转化为稳定的立方ＭＣＭ－ ４８ 材料． 介孔材料的相转变是因为在不同反应温度条件下，ＴＥＯＳ的水解和缩聚所产生的无机硅酸根离子的带电性质和缩合程度不同，从而导致有机／无机离子界面作用力的差异引起的．ＴＧＡ 分析表明随反应温度的提高，材料中无机离子通过静电作用结合的表面活性剂数量减少． ＨＲＥＭ 和Ｎ２ 吸附－脱附分析结果证实了立方有序介孔结构的存在．
The cubic mesoporous silica MCM-48 materials were synthesized through temperature control, and the properties of samples were investigated by using XRD, TGA, HREM and N 2 adsorption-desorption. XRD results show that the mesophases synthesized at low temperature (≤75 ℃) have the poorly-ordered hexagonal structure, while hydrothermal treatment at higher temperature (≥95 ℃) causes the unstable hexagonal phase transforming to cubic MCM-48 forms. The kinetics of the thermal transformation of mesophases can be due to the polymerization and condensation of silicate species at higher temperature, which result in the formation of high_curvatured cubic phase. TGA reveals that the mass loss of mesophases has a tendency to decrease with the increase of hydrothermal temperature. HREM and N 2 adsorption isotherms of MCM-48 materials indicate the well_ordered three_dimensional meso_channels.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
1999年第6期685-692,共8页
Journal of The Chinese Ceramic Society
