Effect of Hydrothermal Conditions on the Microstructure of Brookite Titanium Dioxide

The brookite TiO2 with different morphologies was prepared by hydrothermal method using TiCl4 and NaOH as the starting material. The prepared samples were characterized by XRD and TEM. The effects of pHinitial value, hydrothermal temperature and hydrothermal time on the morphology, crystal phase and crystallite size of TiO2 powder were investigated. The results showed that pHinitial value was the key factor in determining the crystal phase, particle size and morphology of TiO2 powder. With the increase in hydrothermal temperature and hydrothermal time, the crystallite size of brookite TiO2 increased accordingly. The increase of pHinitial value resulted in the rise of hydrothermal temperature and the increase of hydrothermal time needed in the transformation of amorphous TiO2 to brookite phase, at the same time, the crystallite size and particle size became larger. XRD and TEM revealed that the particles of brookite TiO2 were composite particles assembled or combined by nanocrystalline. When pHinitial=9.00~12.00, the brookite TiO2 with single phase was obtained at 200 ℃ for 24 h.