Electronic structure and size of TiO2 nanoparticles of controlled size prepared by aerosol methods

A complete characterization of nanostructures has to deal both with electronic structure and dimensions. Here we present the characterization of TiO2 nanoparticles of controlled size prepared by aerosol methods. The electronic structure of these nanoparticles was probed by x-ray absorption spectroscopy (XAS), the particle size by atomic force microscopy (AFM). XAS spectra show that the particles crystallize in the anatase phase upon heating at 500 oC, whereas further annealing at 700 oC give crystallites of 70 % anatase and 30 % rutile phases. Raising the temperature to 900 oC results in a complete transformation of the particles to rutile. AFM images reveal that the mean size of the anatase particles formed upon heating at 500 oC is 30 nm, whereas for the rutile particles formed upon annealing at 900 oC 90 nm were found. The results obtained by these techniques agree with XRD data. (author)