Growth and characterization of Fe3O4 nanoparticles in silica matrix

Nano-magnetic Fe3O4 particles coated with silica are synthesized. The study of structural and magnetic properties was carried out using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer (VSM) techniques. The VSM results show that these kinds of composite particles exhibit superparamagnetic behavior with zero coercivity and remanence. The magnetic spheroid alumina carriers containing these magnetic composite particles were prepared by an internal gelation process. The SiO2 coatings prevent the reaction between Fe3O4 and Al2O3 during the sintering process and maintain the superparamagnetic behavior of the catalyst carriers.