We report on the formation of titania (TiO2) colloids via the hydrolysis and condensation of alkoxides under a large excess of water. This process is characterized by a rapid precipitation of large aggregates, followed by a slow peptization (deaggregation) induced by the presence of nitric acid. We find that the hydrolysis temperature and the length of the alkoxy group have a minor effect on the size of the peptized colloid. In contrast, the particle size is sensitive to the peptization temperature and exhibits a minimum at 50°C. The presence of alcohols inhibits peptization and results in both larger colloids and longer peptization treatments. The smallest size (∼20 nm in diameter) is obtained when no alcohol is added to the reaction mixture. The results suggest that the formation of TiO2 nanoparticles is controlled by colloidal interactions, whereas chemical factors (the rate of hydrolysis and condensation) have a secondary role.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - Nov 1 1998|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry