Iron oxide in a silica matrix prepared by the sol–gel method

FexOy–SiO2 nanocomposites were prepared by sol–gel method by using two SiO2 sources and Fe(SO4)2·7H2O as raw materials. The amorphous gels were thermally treated up to 1000 °C. The initial gel and the thermally treated samples were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) and infrared spectroscopy. The presence of hematite was confirmed by the obtained Mössbauer spectra which showed the characteristic sextet. The total amount and the size distributions of the hematite nanoparticles can be controlled via the initial precursors and subsequent by annealing conditions.