Nucleation and Crystal Growth of Nanocrystalline Anatase and Rutile Phase TiO2 from a Water-Soluble Precursor

Titanium dioxide (TiO2) has been widely used as an advanced semiconductor and as a white pigment for many years. In recent years, TiO2 has gained much more interest for its semiconducting properties for use as photocatalytic and photovoltaic materials. Understanding the fundamental nucleation and growth mechanisms is crucial to controlling microstructure and properties for these applications. Nanosized rutile and anatase particles were synthesized from a water-soluble titanium(IV) precursor using a hydrothermal method. The impact of various hydrothermal conditions on the formation, phase, morphology, and grain size of the TiO2 products was investigated using XRD, TEM, and FTIR. At near neutral pH, aggregated rutile rods are formed. By increasing the alkalinity of the reaction medium, the anatase phase was favored and, as expected, larger particle sizes resulted from longer duration reactions. The effects of reaction conditions are discussed with respect to coordination chemistry and coarsening mechanisms.