The effect of pH on the nucleation of titania by hydrolysis of TiCl4.

We have proposed and experimentally tested a phenomenological model of nucleation of a specific polymorphic phase of titanium dioxide (anatase, rutile, brookite) resulting from the interaction of Ti4+ hydroxocomplexes at different pH values of reaction medium. The degree of hydrolysis was determined as a function of pH for the monomers formed during the hydrolysis of titanium tetrachloride. Mixtures of anatase and brookite with an average size of coherently scattering domains of 5 nm and particles of ellipsoidal shape were obtained by precipitation at pH = 8. At the same time, nanoparticles of rutile with rod-like morphology and an average size of 10 nm were obtained at a pH = 1. [ABSTRACT FROM AUTHOR]