Effect of Thermal Treatment on Nanosized Brookite-to-Rutile TiO2 Phase Transformation Prepared by Sol-Gel Method

This paper describes heat treatment temperature effect on the phase transformation of titanium dioxide (TiO2) prepared using metal organic precursors as starting materials. X-ray diffraction (XRD) was used to investigate the structural properties of as prepared TiO2 powder and calcined at different temperatures (100, 300, 500, 700) ?C. the results showed that the prepared and 100 ?C treated samples were amorphous, and have typical peaks of TiO2 polycrystalline brookite nanopowders after calcined at (300 ?C), which confirmed by (111), (200), (040), and (231) diffraction peaks. Also, XRD pattern showed the presence of crystallites of anatase with low proportion of rutile phase reaches (27.3%) weight fraction where calcined at (500 ?C). With further increase in the calcination temperature, i. e. to (700 ?C), formation of complete rutile phase has been observed. The crystallite size of TiO2 nanopowders was calculated by Scherer's formula and showed that the crystallite size decreased and then increased with increasing the annealing temperature.