Preparation of Monodispersed and Nano-sized Spherical SiO_2 Particles by Emulsion Method

摘要

Spherical nano-sized SiO_2 particles have been synthesized from sodium silicate by emulsion method. The influence of emulsifier content and mixing time on the morphology and particle size distribution of the resulting materials was investigated. The characteristics of the obtained SiO_2 particles were examined by means of XRD, SEM, TEM, and PSA. The monodispersed shperical SiO_2 with the average particle size 20 nm was obtained at a emulsifer content of 3vol% and mixing time of 60 min using ultrasonic disrupter. After calcining at 1200℃ for 2 hrs, the amorphous SiO_2 transformed wholly to the crystalline cristobalite. As increase in emulsifier content from 1 to 3 vol% did not nearly influence on the morphology of SiO_2 particle but slightly changed the particle size distribution. The average particle size of SiO_2 decreased significantly from 100 nm to 20 nm with increasing the mixing time.