Magnetic properties of gamma-Fe2O3-SiO2 aerogel and xerogel nanocomposite materials

The properties of aerogel and xerogel iron oxide-silica nanocomposites prepared by the sol-gel method were investigated by thermal analysis, X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and susceptibility measurements. Pure maghemite nanoparticles were obtained starting from both xerogel and aerogel samples, with particles of average size around 5 nm which tend to aggregate into the silica matrix. The role of magnetic interparticle interactions, which have a strong influence on the magnetic properties, is discussed.