二氧化硅溶胶体系的电导行为

二氧化硅溶胶的导电性与其储存稳定性及纳米材料的制备和应用密切相关。本文通过Stöber法制备了分散性较好的非晶型二氧化硅纳米微球,用激光粒度分析仪、高分辨透射电子显微镜和X射线衍射仪对微粒进行了表征。通过电导率的变化监测了不同条件下的溶胶-凝胶动力学过程,并详细地研究了影响二氧化硅溶胶体系电导行为的各个因素。实验结果表明,氨水用量对溶胶-凝胶过程的平衡时间有很大影响,氨水用量少,体系平衡时间短,反之亦然。二氧化硅的浓度、粒径、分散介质的温度、pH值和电解质浓度对溶胶体系的电导率都有显著的影响,并得出了二氧化硅的浓度和体系温度与电导率之间呈线性关系,同时发现,硅溶胶体系的电导率与胶体粒子总的比表面积成正比,与颗粒表面的ζ电位也密切相关。

Study on the electric conductivity of silica sol system

Electric conductivity of silica sol is closely related to its storage stability and preparation and application of nanomaterials. Mono-dispersed non-crystalline silica nanospheres were fabricated by Stöber process and the resulted microparticles were characterized by laser particle size analyzer, high-resolution transmission electron microscope and X-ray diffractometer. The sol-gel dynamic processes at various conditions were monitored by conductivity variation, and factors affecting the electric conductivity of silica sol system were discussed. The experimental results indicate that the dose of aqueous ammonia has a large impact on the equilibration time of sol-gel process and it decreases with the decrement of the dose of aqueous ammonia, vice versa. The electric conductivity of silica sol system is apparently influenced by the concentration and diameter of SiO₂ microparticles, system temperature, pH value and the electrolyte concentration of dispersion medium. It is concluded that the electric conductivity shows a good linear relationship with SiO₂ concentration and system temperature. Meanwhile, it is found that the electric conductivity is proportional with the total surface area of the microparticles of silica sol system, and is closely related to the zeta potential of SiO₂ particle surface.