Zarrin Khame Foroshʼ - Department of Materials Science and Engineering, Iran University of Science and Technology, Tehran, Iran
V. Tajer-Kajinebqf - Department of Materials Science and Engineering, Iran University of Science and Technology, Tehran, Iran
H. Sarpoolaky - Department of Materials Science and Engineering, Iran University of Science and Technology, Tehran, Iran

Nowadays micro and nano spheres of ceramic materials were progressively synthetized for different applications such as pigments, fillers, catalysts, photographic materials, medicines, etc. In the present work, monodispersed silica spheres were coated with TiO2 nanoparticles using colloidal titania sol via a simple electrostatic attraction strategy. Monodispersed silica spheres with diameters ranging from 500-700 nm were prepared by the Stöber method and colloidal titania sol was obtained by a hydrolysis-condensation reaction of tetra isopropyl orthotitanate (Ti(OC3H7)4) in acidic media. SiO, spheres were coated with TiO, nanoparticles in the different weight ratios of TiO2/SiO2. The asprepared products were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The results of DLS showed that particle size distribution of TiO, sol was in the 12-38 nm range. It was found that uniform coating of TiO, could be deposited on the surface of silica spheres by adjusting the pH of TiO2 sol in the 1.6 range. SEM images showed perfectly smooth surfaces of the silica spheres; but when TiO2 nanoparticles were deposited on the surface of silica spheres, a loose Corresponding author. Tel:+982177240540-550 (2871); Fax:+982177240480and rough shell was made. Also FT-IR results confirmed the existence of Ti-O-Si chemical bonding at the interface between TiO2 nanoparticles and silica sphere surfaces.

TiO, Nanoparticle; Silica Sphere; Heterocoagulation; Sol-Gel