Sol-gel synthesis of CoFe2O4:SiO2 nanocomposites - insights into the thermal decomposition process of precursors

Succinate precursors dispersed in the silica matrix were obtained by sol-gel synthesis using Co and Fe nitrates, 1,4-butanediol and tetraethyl orthosilicate. The thermal decomposition of Co and Fe succinates into cobalt ferrite (CoFe2O4) at different CoFe2O4:SiO2 molar percentages was studied by thermal analysis, Fourier transformed infrared spectrometry (FT-IR) and X-ray diffraction. The morphology of nanoparticles was identified by transmission and scanning electron microscopy. The formation of succinates in the pores of the silica matrix and their decomposition to CoFe2O4 spinel was confirmed by the FT-IR spectra. The nanocrystallites size (7-33 nm) increases with the decrease of SiO2 content, suggesting that the growth process of nanoparticles is reduced in the presence of silica matrix.