Structure, Magnetic and Photochemical Properties of Fe–TiO2 Nanoparticles Stabilized in Al2O3 Matrix

Fe–TiO 2 nanoparticles with Fe concentration from 0.24 to 5 wt % were synthesized in a Al 2 O 3 matrix through multiple impregnations from organic solutions of Ti n -butoxide and Fe acetylacetonate. Microstructure, morphology and magnetic properties of the composites were studied using X-ray analysis, transmission electron microscopy, energy-dispersive analysis, Mössbauer spectroscopy and magnetic susceptibility. It was shown that the deposition of the solution with low concentration of Ti n -butoxide leads to the formation of mostly extensive Fe–TiO 2 films with a small fraction of individual Fe–TiO 2 nanoparticles. On the contrary, the increase of Ti n -butoxide concentration results in the formation of a great number of individual Fe–TiO 2 nanoparticles on Al 2 O 3 . The size of these particles increases from 2–3 nm to 5–8 nm with the increase of Fe content in the samples from 0.24 to 1.0 (wt %). Mössbauer spectroscopy revealed two types of magnetic ions. The first type of paramagnetic Fe 3+ demonstrate spin–lattice relaxation properties while another one substitutes Ti 4+ in the TiO 2 structure thus forming Fe–TiO 2 stabilized particles in the matrix. According to the magnetic data antiferromagnetic and ferromagnetic types of exchange spin coupling occur in Fe–TiO 2 /Al 2 O 3 composites. The increase of Fe concentration in the composites from 1 to 5 wt % results in the narrowing of the TiO 2 band gap from 3.2 to 2.7 eV and shifting the absorption edge in visual spectrum from 350–400 to 450–500 nm.