Crystallite size distributions and particle size distributions were determined by TEM, XRD, and SAXS for three commercially available TiO₂ samples and one homemade. The theoretical Guinier Model was fitted to the experimental data and compared to analytical expressions. Modeling of the XRD spectra showed a difference between the analytical size dependent expressions and the theoretical Guinier Model. Primay particle size distributions were extracted from SAXS measurements by the hard sphere model including the interparticle interference factor. The size distributions from SAXS were smaller than the size distribution obtained from the XRD experiments; however, a good agreement was obtained between the two techniques. Electron microscopy, SEM and TEM, confirmed the primary particle sizes, the size distributions, and the shapes obtained by XRD and SAXS.

The SSEC78 powder and the commercially available powders showed different morphologies. The SSEC78 powder showed the narrowest sizes distribution while UV100 and TiO2_5nm consisted of the smallest primary particles. SSEC78, UV100, and TiO2_5nm consisted of both primary particles as well as a secondary structure comprised of nanosized primary particles agglomeration into larger clusters. P25 showed the largest primary particle size, but didn't show a secondary structure.