Fe effect on the optical properties of TiO(2):Fe(2)O(3) nanostructured composites supported on SiO(2) microsphere assemblies

The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO(2) films supported on silica (SiO(2)) opals has been studied. TiO(2):Fe(2)O(3) films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO(2) opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO(2):Fe(2)O(3)/SiO(2) composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO(2), the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO(2) decrease as the Fe(+3) ion concentration increases.