Thermal behaviour study of some sol-gel iron-silica nanocomposites

Two series of nanocomposites from the FexOy-SiO2 system, containing 20 mass% iron oxide were prepared by the alkoxide route of the sol-gel method, in the absence and presence of catalyst. The silica gel has been obtained using tetraethoxysilane. The iron(III) nitrate nonahydrate has been used as iron oxides source. The samples have been prepared in identical conditions, differing only by the gelation times, induced by different surface of evaporation/volume (S/V) ratios of sol let to gelify. Thermal analysis data have established the thermal treatments conditions of the prepared samples and were correlated with X-ray diffraction, IR spectroscopy and TEM results, in order to accomplish a complete structural characterization. The correlation between the structural modifications of the FexOy-SiO2 nanocomposites and different conditions of drying has been established.