Abstract

Nano/micro-sized titania powders were prepared by a hydrothermal method using an aqueous solution of TiCl₄ as precursor. The influence of the concentration of the aqueous TiCl₄ solution on the formation, phase, morphology, and grain size of the products was investigated at various reaction temperatures and times. Increasing the concentration of TiCl₄ favored the formation of rutile type TiO₂. When [TiCl₄] < 0.5 mol dm⁻³, the products were a mixture of rutile type and anatase type powders, the percentage of rutile type powders in all crystalline products varied with reaction time. When [TiCl₄] = 0.5 mol dm⁻³, the product was a pure rutile type powder. The powder size was related to the concentration based on the nucleation and growth theory of supersaturated solutions. A growth unit model was proposed to explain the phase formation.