SYNTHESIS OF MAGNETIC SBA-15 AND Fe–SBA-15 MESOPOROUS NANOCOMPOSITES WITH COBALT FERRITES

摘要

A new nanocomposite based on SBA-15 mesoporous materials combined with Fe_2O_3 and CoFe_2O_4 nanoparticles was prepared via sol–gel growth. The nanostructures and magnetic properties of the SBA-15 nanocomposite were investigated by X-ray diffraction topography, high resolution transmission electron microscopy, and vibrating sample magnetometer. Results indicate that α-Fe_2O_3 nanoparticles are present in the frame or micropores of SBA-15 (denoted as Fe–SBA-15 below) and that CoFe_2O_4 nanoparticles are confined in the mesoporous channels of Fe–SBA-15. Our results also reveal that the addition of CoFe2O4 and α-Fe_2O_3 magnetic nanoparticles critically affects their magnetic properties. The saturation magnetization of the SBA-15 nanocomposite is attributed to ferrimagnetic CoFe_2O_4 nanoparticles and antiferromagnetic α-Fe_2O_3 nanoparticles, whereas the coercivity increases with the content of CoFe_2O_4.Moreover, the presence of the couple exchange interaction between the magnetic nanoparticles is confirmed, which can enhance the magnetic properties of the SBA-15 nanocomposite.