Low temperature synthesis of anatase and rutile titania nanopowders by hydrolysis of TiCl4 using ammonia gas

A facile method is presented for preparing anatase and rutile titania nanopowders by hydrolysis of TiCl4 using ammonia gas as precipitator at low temperatures (30-60 degrees C). The influences of reaction temperature, pH value and aging time on the formation of titania nanopowders were systematically investigated. The prepared titania powders were characterized by X-ray diffraction (XRD), thermogravimetric (TG/DTA), scanning electron microscopy (SEM), transmission electron microscope (TEM), and dynamic light scattering (DILS). It was found that reaction temperature and pH values were the most influential factors in phase control of the nanopowders. Rutile phase titania was obtained at low temperature (30-60 degrees C) if pH <= 1. However, as pH >= 4. the anatase phase was obtained in the same temperature range. Moreover, the aging time had no affect on the phase change of titania sample. Anatase converted completely to rutile phase after annealing at 700 degrees C. Polyethylene glycol 1000 was used as a steric dispersant in this study, which made the product more uniform and spherical. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.