Abstract: By using technical grade TiOSO₄ as the precursor and urea as the precipitating agent, nano-crystalline anatase TiO₂ powders were prepared by hydrothermal synthesis. The initial pressure of the system was 6MPa. Stirring speed was fixed at 300r/min. Reaction temperature was ranged from 110℃ to 150℃ with holding time from 2h to 8h and the concentration of the precursor was ranged from
0.25～1.5mol/L. The grain size, phase composition and specific surface area of the synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and BET methods. XRD results show that the synthesized powders are all anatase. Calculated grain size is from 6.7 to 10.6nm by Scherrer method. The specific surface area of the powders is ranged from 124 to 240m²/g. The grain size of the powders increases with the increase of the reaction temperature, holding time and precursor concentration. When the precursor concentration is more than 0.5mol/L, the specific surface area decreases with the increase of holding temperature, holding time and precursor
concentration. When the precursor concentration is less than 0.5mol/L, the
specific surface area increases with the increase of precursor concentration.

Key words: hydrothermal synthesis, nano-TiO2, anatase, TiOSO4