| Abstract
| - The structural and magnetic properties of CoFe2O4−SiO2 nanocomposite porous aerogels have beensystematically investigated by XRD, TEM, and SQUID magnetometry. The preparation of the samples wasperformed by a cogelation sol−gel route which allows one to obtain nanocomposites with high purity andhomogeneity and to control the composition of the sample in terms of ferrite loading in the nanocomposite.In particular, the compositional effect on both the structural and magnetic properties of the nanocompositewas investigated in two nanocomposites with relative CoFe2O4 amounts of 5 and 10 wt %. The characterizationshows both similarities and differences in the structural evolution of the nanophases within the amorphousporous matrix of the two nanocomposites as a function of the calcination temperature. In both samples theferrite nanoparticles are formed above 750 °C; however, a slower structural evolution is observed in thenanocomposites with 5 wt % CoFe2O4. The nanocomposites display superparamagnetic behavior with blockingtemperature that increases with both the ferrite amount and the calcination temperature. The importance ofcombining information from different techniques is also discussed, with particular reference to nanocrystalsize determination. The results provide insights into the characterization of innovative materials and on howthe compositional and microstructural features affect the properties of magnetic nanocomposites.
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