Microwave-Induced Combustion Synthesis of Nanocrystalline TiO2–SiO2 Binary Oxide Material

Abstract

A nanocrystalline titania–silica (1:1 molar ratio) binary oxide material was synthesized by microwave-induced combustion process in a modified domestic microwave oven (operated at 2.45 GHz frequency and 700 W power) in approximately 60 min from in situ synthesized titanyl nitrate and siliconyl nitrate using urea as fuel. For the sake of comparison, two different types of TiO2–SiO2 powders were also synthesized by the sol-gel and the co-precipitation methods. All the synthesized powders were characterized with the help of thermogravimetriy/differential thermal analysis, x-ray diffraction, transmission electron microscopy (TEM), and Brunauer–Emmett–Teller surface area measurements and the results compared. The as-synthesized TiO2–SiO2 powder obtained by the combustion process showed an average crystallite size of 10 nm and the specific surface area of 115 m2g-1. Among the three differently synthesized TiO2-SiO2 powders, only the microwave-induced combustion synthesis yielded crystalline material. TEM in particular confirmed the presence of nano-sized particles in the microwave-induced combustion-synthesized powder. Among the three analogies, microwave synthesis was found to be superior in terms of ease of processing leading to time and power savings.