Morphology of rutile and brookite nanocrystallites obtained by X-ray diffraction and Rietveld refinements

Titanium oxide was prepared under hydrothermal conditions from a very acidic solution, with titanium butoxide as titanium precursor and hydrochloric acid as the source of protons, the pH was regulated adding water to this solution. The H(2)O/HCl molar ratio was varied from 10 to 50; this ratio, together with the synthesis temperature, which varied between 90 degrees C and 200 degrees C, determined the phase concentrations Samples contained mainly the mama polymorphs ruble and brookite, the highest concentration of this last phase was obtained for the ratio of 20 and the synthesis temperature of 120 degrees C. The synthesized powder was analyzed with X-ray powder diffraction, refinement of the crystalline structures and transmission electron microscopy The refinement provided information not only about the average crystallites dimensions but also about their morphologies. which were similar to those observed by transmission electron microscopy. The refinement also shows that the lattice parameters of ruble changed with H(2)O/HCl molar ratio and synthesis temperature, while those of brookite were almost constant (C) 2009 Elsevier B V All rights reserved.