Composite materials based on nanoporous SiO2-matrices and TiO2 nanoparticles

SiO2:TiO2 composites were obtained by saturation of SiO2-matrices (with a porosity of 30 % and similar to 42 %) with a suspension of TiO2 nanoparticles and subsequent annealing to 700 degrees C. It was shown that, due to annealing of the composites in the temperature range of 400-700 degrees C, there was observed agglomeration of TiO2 nanoparticles in the pores of the SiO2-matrices, that manifested itself in an increase of the absorption in wavelength range of 390-800 run. The presence of diffraction rings in the electron microdiffraction images confirms formation of TiO2 crystallites in SiO2:TiO2 composites. The content of titanium in the composite less than 1 % relative to silicon did not allow to reveal crystalline TiO2 phase in the composites by powder X-ray diffraction method. TiO2 is probably present in the composites based on SiO2-matrices with high porosity both in the form of crystallites and in amorphous state.