The sol-gel method was used to prepare nickel oxide-silica and nickel-silic
a nanocomposite materials and the corresponding silica matrices. Different
drying conditions were used to obtain aerogel and xerogel materials. The sa
mples were characterized by thermal analysis, x-ray diffraction, N-2-physis
orption, transmission electron microscopy techniques, and infrared spectros
copy. Aerogel samples had a much higher surface area than the xerogel sampl
es; moreover, different supercritical drying conditions gave rise to a diff
erent porous structure, which influenced the size and distribution of the n
anoparticles in the matrix.