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LiCl was used to improve the surface charge of SiO2 colloidal spheres prepared by stöber method. And vertical deposition method was used to synthesize the photonic crystal with modified SiO2 colloidal spheres. The micromorphology, electrical properties and optical properties were characterized by scanning electron microscope (SEM), zeta potential instrument and UV/VIS/NIR spectrophotometer. The surface charge of SiO2 colloidal spheres can be improved by LiCl solution, and the Zeta potential increases with the increment of LiCl concentration and NH3 concentration. The position of the transmission dip of the photonic crystals is close to the experimental value.

Two Pechini sol-gel processes were used to prepare titania-silica composite particles. The dynamic oxidation behavior of the TiO2-SiO2 powders has been characterized by thermogravimetry-differential scanning calorimetry (TG-DTG-DSC). The crystal phase and microstructure of the composite particles were investigated by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The effects of Si:Ti molar ratio and sol-gel process on the TiO2-SiO2 powders were studied. The preparation of the polymeric precursors can influence the morphology of obtained TiO2-SiO2 composite particles. The spherical TiO2-SiO2 composite particles which are 20 nm~400 nm in diameter appear in gel-1 system. However, the TiO2-SiO2 powders obtained by gel-2 system are irregular in shape and 2~15 μm in diameter which show a loose porous structure consisted of very fine granules.