Glass-metal nanocomposite synthesis by metal organic route

Glass-metal nanocomposites incorporating ultrafine particles of iron, nickel, cobalt and manganese, respectively, in a silica glass matrix have been prepared by heat treatment of a gel derived from a sol containing silicon tetraethoxide and a suitable metal organic compound. Metal particles in all the nanocomposites are isolated and spherical-shaped with diameters ranging from 3 to 10 nm. Films of these nanocomposites with thickness of the order of a few micrometres have been prepared on glass slides by a simple dip-and-pull technique. Optical absorption spectra of the nanocomposite films have been measured over the wavelength range 200 to 2000 nm. Effective medium theories of Maxwell-Garnett and Bruggeman, respectively, have been used to calculate theoretically the optical absorption of these materials. The Maxwell-Garnett theory gives results which are in better agreement with experimental data than those obtained from Bruggeman formalism. The filling factor f as estimated from the least-squares fit of the experimental results with the Maxwell-Garnett theory has a value in the range 1 to 4%.