硝酸钠熔盐体系下二氧化硅低温晶化研究

Study of Silica Crystallization at Low-Temperature in NaNO_3 Molten Salts

以介孔氧化硅分子筛SBA-15为原料,采用低温熔盐法制备了晶态的方石英.X射线衍射结果表明,二氧化硅(SiO_2)骨架由无定型态转变为晶态的方石英相的最佳条件为:SiO_2与NaNO3的质量比例为1∶50,温度为500℃,保温时间为6h.此外,晶化机理研究表明,Na+和三嵌段表面活性剂P123(聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物,PEO-PPO-PEO)是实现SBA-15低温晶化的两个关键因素.

A low-temperature molten salt method was described to synthesize cristobalite by using mesoporous silica SBA-15 as the origin material. The X-ray diffraction results show that the optimum condition of the transformation of cristobalite nanoparticles from SBA-15 is that the mass ratio of SiO2/ NaNO3 is 1 ： 50 and the temperature is 500℃ with holding time for 6 h. In addition, the study of crystallization suggests that the Na^＋ and the organic material P123 are two prerequisite factors to realize the low temperature crystallization.