Nucleation and growth of self-assembled nanofibre-structured rutile (TiO2) particles via controlled forced hydrolysis of titanium tetrachloride solution

In this study the production of rutile (TiO2) nanostructured powders by forced hydrolysis of aqueous Ti(IV) chloride solutions was investigated in terms of precipitation kinetics and nucleation and growth mechanism over the temperature range 70-90 degrees C and Ti(IV) concentration 0.5-1.5 M. The precipitation kinetics was found to follow the Avrami model exhibiting a slow induction-nucleation stage and accelerating growth stage. The type and speed of agitation was found to have a pronounced effect on the nucleation kinetics that required the adoption of a mechanically agitated (1000 rpm) reactor for the obtainment of reproducible results. An increase in Ti(IV) chloride concentration was found to have a negative effect on kinetics pointing to differences in a precursor complex formation and polymerization behaviour. The obtained nanostructured rutile powder had a spheroidal particle morphology with the interior of the particles characterized by a nucleation core and self-assembled elongated fibres. The nucleation core consisted of primary aggregates of elementary nanocrystallites of similar to 10-20 nm size. The nanofibres were found to form via preferential growth of the (1 1 0) atomic planes. The nanostructured rutile powder exhibited high specific surface area in the order of 80 m(2)/g. (C) 2009 Elsevier B.V. All rights reserved.