Preparation and polishing properties of SiO2-CeO2 mixed oxides

SiO2-CeO2 mixed oxides were prepared by precipitating cerium lon with ammonia from solution containing cerium chloride ind nano-silica, which was prepared by means of sol-gel method using ethyl-orthosilicate as raw material. Their crystalline phase type, morphology, crystalline size, particle size and potential were characterized, and the polishing rate was determined. The synthesized mixed oxides were nanocrystalline ceria with cubic fluorite structure,the calculated average crystalline sizes based on the half peak width and Sherrer formula were less than 100 nm, even lower than 10 nm. With the increase of mass ratio of SiO2 to CeO2 and the decrease of calcination temperature, the crystalline size decreased, however, the specific surface area and the particle sizes determined by laser scattering method, which ranged from 2 000 to 3 000 nm, increased. The dependence of calcination temperature on the zeta potential, particle size and polishing rate for three glasses all showed peak value at around 800 degrees C. These facts demonstrate that there exists a direct relation between polishing rate and particle zeta potential as well as the corresponding physical properties such as particle size and suspension stability. On the other hand, the negative zeta potential and the polishing rate for three glasses were all increased with the increase in the addition amount of SiO2 in the mixed oxide. Therefore, doping SiO2 with CeO2 is an effective route to enhance polishing rate, and the best calcining temperature lies around 800 degrees C.