Size and shape characterization of TiO2 aerogel nanocrystals

TiO2 aerogels were obtained by supercritical evacuation of solvent from gels prepared through HCl controlled hydrolysis condensation reactions of titanium isopropoxide in isopropanol. XRD line broadening analysis was used to characterize powders resulting from the calcination of aerogels. Because of diffraction lines overlapping at high angles, the separation between crystallite size and microstrain effects could not be satisfactorily achieved by pattern decomposition. Whole pattern fitting was then used to demonstrate that TiO2 nanocrystals are practically free of microstrain. According to this result, the analysis of integral widths based on peak by peak fitting was performed to analyze the observed anisotropic size effect of prismatic shaped titanium oxide crystals, approximately 30 by 15 by 15 nanometers in size. These results are in good agreement with High Resolution Transmission Electron Microscopy observations.