Synthesis of tin oxide nanosized crystals embedded in silica matrix through sol-gel process using alkoxide precursors

Materials made of tin oxide nanocrystals homogeneously dispersed into a silica glass matrix have been elaborated through sol-gel processing. Addition of strong acids was used to control the hydrolysis-condensation in tin and silicon alkoxides mixed alcoholic solutions. Fourier transform infrared spectroscopy (FTIR) and Small angle X-ray scattering (SAXS) measurements show that the introduction of HCl allows to synthesize gels containing up to 50% of tin oxide precursor without significant modification of the pure silica gel network. Thermal treatments of slowly dried bulk gels induce the crystallization of tin oxide nanoparticles. After firing at 1000 °C, dense materials containing tin oxide nanocrystals (with a mean diameter close to 1-2 nm) are obtained. The crystal size distribution was estimated by X-ray diffraction line profile analysis. The narrowness of this distribution makes these materials interesting for optical applications.