High Anatase-Rutile Transformation Temperature of Anatase Titania Nanoparticles Prepared by Metalorganic Chemical Vapor Deposition

Abstract

Anatase titania nanoparticles with a particle size of about 10 nm are prepared by metalorganic chemical vapor deposition (MOCVD) and the anatase-rutile tranformation of the nanoparticles is investigated and discussed. The results show that anatase-rutile transformation takes place in a wide range of temperature. When annealing time is 1 h, the anatase-rutile transformation temperature of the nanoparticles is as high as 900 to 1200°C, which is comparable to that of micrometer-sized titania. Based upon X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) results, a possible transformation mechanism is proposed. The high transformation temperature of the nanoparticles is primarily attributed to the retardation of the initial particle growth of the anatase phase due to the lattice strains in the nanoparticles before transformation proceeds.