Synthesis and optical properties of TiO₂-based magnetic nanocomposites

Highlights: • Magnetic titania@silica nanoparticles were synthesized by the single step laser pyrolysis. • Fe(CO)₅, TiCl₄, HMDSO and O₂ from air were the precursors and C₂H₄ was the sensitizer. • Samples present a typical character of diluted magnetic oxide systems. • Samples have a lower bandgap energy (down to E_g = 1.85 eV) than the P25 Degussa. - Abstract: Magnetic titania nanoparticles covered/embedded in SiO₂ shell/matrix were simultaneously manufactured by the single-step laser pyrolysis. The present study is a continuation of our previous investigations on the TiO₂/Fe and TiO₂/HMDSO (hexamethyldisiloxane) derived-systems. The aim of this work is to study the synthesis by IR (Infrared) laser pyrolysis of magnetic TiO₂ based nanocomposites which implies many concurrent processes induced in the gas phase by the laser radiation. The dependence between characteristic properties and the synthesis parameters was determined by many analytical and complementary methods: XRD (X-ray diffraction) structural analysis, UV–vis (ultraviolet–visible) and EDAX (energy-dispersive X-ray) spectroscopy, TEM and HRTEM (transmission electron microscopy at low and high resolution) analysis and magnetic measurements. The results of analysis indicate the presence of disordered silica, Fe, α-Fe₂O₃ and mixtures of anatase and rutile phases with mean crystallite dimensions (in the 14–34 nm range) with typical character of diluted magnetic oxide systems and a lower bandgap energy (E_g = 1.85 eV) as compared with TiO₂ P25 Degussa sample