Preparation and characterization of nanocomposite MgFe2O4/SiO2

Nanocomposites MgFe2O4/SiO2 were successfully synthesized by the sol-gel method in the presence of N, N-dimethylformamide (DMF). The formation of pure MgFe2O4 was confirmed by powder X-ray diffraction (XRD) and electron diffraction. The structural evolution of MgFe2O4 nanocrystals was followed by powder X-ray diffraction and IR absorption spectroscopy. The formation of spinel structure of MgFe2O4 started at 800 °C, and completed at 900 °C. The transmission electron microscopy (TEM) measurements suggest that the particle sizes increase with the increasing annealing temperature, and the mean particle sizes of the spherical samples annealed at 800 °C, 900 °C and 1 050 °C are ca. 3 nm, 8 nm and 11 nm, respectively. Magnetization measurements at room temperature and 78 K indicate superparamagnetic nature of these MgFe2O4 nanocrystals.