Comparison Study on the Microstructure of Nanocrystalline TiO2 in Different Ti-Si Binary Oxides

Three different Ti-Si oxide structuares,silica supported titania,silica coated titania and intimately mixed silica- titania,containing 10%-40% SiO,were made by sol-gel process.The variations of microstructure parameters of nanocrystalline(nc)TiO-anatase in the three kirds of binary oxides,including in-plane spacing d,cell constants(a,c),cell volume V,cell axial ratio c/aand crystal grain size,were comparatively investigated by high resolution transmission electron microscopy(HRTEM)and X-ray diffraction(XRD).It is found that the microstructure parameters vary remarkably with increasing SiOcontent and annealing temperature.Different structured Ti-Si binary oxides lead to different variation tendencies of microstructure parameters.The more SiOthe binary oxide contains,the more lattice defects of nc TiO-anatase appear;diffusion or migration of Si cations could be an important influential factor in the variations of microstructure.The grain size of nc TiOin the three kinds of binary oxides not only depends on SiOcontent and annealing temperature but also on the degree of lattice microstrain and distortion of nc TiO-anatase.Both grain size and phase transformation of nc TiO-anatase are effectively inhibited with increasing SiPcontent.