The synthesis of nanosized TiO2 powder using a sol-gel method with TiCl4 as a precursor

Abstract

Nanosized TiO₂ powder with anatase structure was synthesized by a sol-gel method using TiCl₄ ethanol solution as a precursor. The grain size of TiO₂ powder was homogenous and was about 10 nm after the precursor was calcined at 500 °C for 1 hour. Anatase TiO₂ powder formed after the precursor was calcined at a temperature ranging from 300 °C to 550 °C. The gelatinizing mechanism of TiCl₄ in ethanol solution can be described as followings. When mixed with ethanol, TiCl₄ reacted with ethanol to form TiCl _x (OCH₂CH₃)_{4 − x} species and HCl gas. During gelatinizing process, TiCl _x (OCH₂CH₃)_{4 − x} species absorbed water from atmosphere to form Ti(OH)₄ precursor, which was polymerized to be an inorganic polymer. The formation of inorganic polymer of Ti(OH)₄ was intensified with gelatinizing time. In contrast, the organic component was removed from the precursor. The formation of anatase TiO₂ can also be promoted by increasing gelatinizing time. The influence of alcohol on the reacting progress and dispersivity was also studied. The size and activity of alcohol molecule were found to have influence on the polymerization and mineralization degree of the precursor and the dispersivity of TiO₂ powders.