Iron oxide-silica aerogel and xerogel nanocomposite materials

The sol-gel method was used to prepare iron oxide-silica nanocomposite materials. Different drying conditions were used in order to obtain aerogel and xerogel materials. The samples were characterized by thermal analysis, X-ray diffraction (XRD), N2-physisorption and transmission electron microscopy (TEM) techniques. Aerogel samples have a much higher surface area than the xerogel samples; moreover, different supercritical drying conditions give rise to a different porous structure. The stabilization of the maghemite phase in the xerogel nanocomposites depends on the iron content and it is more difficult in the aerogel samples. The early sol-gel preparation stages also play an important role.