镁掺杂对SiO_2有机-无机杂化溶胶性能的影响

Effect of Magnesium Doping on the Properties of SiO_2 Organic-inorganic Hybrid Sol

采用溶胶-凝胶法制备甲基化改性SiO_2溶胶,并在此基础上加入Mg(NO_3)2·6H_2O制备镁掺杂SiO_2有机-无机杂化溶胶。利用紫外-可见光谱、红外光谱、拉曼光谱、X射线电子衍射(XRD)对其进行表征分析,考察镁掺杂对甲基化改性SiO_2溶胶结构的影响,研究不同镁掺杂量对杂化溶胶性能的影响。结果表明,随着镁掺杂量的增加,溶胶体系的黏度、折射率、密度和黏滞性活化吉布斯自由能逐渐增加,反应速率常数逐渐减小。镁掺杂增强了M-SiO_2溶胶对紫外光的吸收,对杂化溶胶的主要结构和甲基化改性无明显影响。Mg/M-SiO_2溶胶和凝胶材料中镁元素主要是以Mg(NO_3)_2·6H_2O的形式存在,材料经过400℃焙烧4 h后,Mg(NO3)2·6H2O完全分解为Mg O。

Methyl-modified silica （M-SiO2 ） sol was prepared by sol-gel method, and the addition of Mg（ NO3 ）2 ·6H2O on the basis of this method to prepare magnesium-doping SiO2 organic-inorganic hybrid sol, which was then characterized by Ultra-violet and visible spectroscopy, and infrared spectroscopy and Raman spectroscopy and X-ray diffraction. The effect of different magnesium doping amount on the properties of hybrid sol was studied. The results show that, with the increase of magnesium doping, the viscosity, refractive index, density and viscous activation Gibbs free energy of the sol system increased gradually and the reaction rate constant decreased. Magnesium-doping could enhance the absorption of ultraviolet light of M-SiO2 sol and had no obvious effect on the main chemical structure and methylation of M-SiO2 sol. Magnesium element existed in the form of Mg（NO3 ）2·6H2O in the magnesium-doping M- SiO/sol and gel materials. Mg （NO3 ）2·6H2O was completely decomposed to MgO if subjected to calcining at 400℃ for 4 h.