Characterization of porous nanocomposites formed by cobalt ferrites dispersed in sol-gel silica matrix

Abstract

Composites of cobalt ferrite particles dispersed in a silica matrix (CoFe2O4/SiO2) were prepared by the sol-gel process using tetraethylorthosilicate (TEOS) as a precursor of silica and metallic nitrates as precursors of ferrite. Samples of SiO2 and CoFe2O4/SiO2 were prepared in monolithic shape, dried at 110.C, treated at various temperatures and their characteristics were compared. After the thermal treatment, the surface area of the silica matrix decreased, above 700.C it densified, and above 1100.C it crystallized. The same heat treatment in the composite led to the crystallization of CoFe2O4 particles in the SiO2 matrix and the increase in particle size, with the consequent increase in magnetization. The presence of particles in the matrix reinforced its structure, avoiding large changes in surface area and porosity and in the structure of the matrix after high temperature thermal treatment.