Size Effect on the Structure and Optical Properties in Nanocrystalline SrTiO3

SrTiO3 nanoparticles can be prospective materials for different physical, chemical and technical applications as dielectric components, materials for catalysis and optics. Particle control may lead to new effects especially when the size becomes comparable with the fundamental dimensional characteristics such as domain size, exciton or electron length, i.e. at the level of nanomaterials. The powders of titanate with perovskite structure and particle size of 5-60 nm were obtained by solvothermal or citrate sol gel methods. The tendency to the lattice constant increase with particle size decrease was observed. However, the dependence of optical gap on the particle size looked unusually which was connected with the structure modifications during sample processing. It was also observed that the finest 5 nm powders contained significant lack of Sr, but perovskite structure was preserved. After thermal treatment TiO2 formation was found, likely providing a composite with ultrafine SrTiO3 nanoparticles inside TiO2 shell.