Magnetic ordering of ferric oxide within SiO2-based mesoporous materials

Nanostructural ferric oxide was encapsulated within one-dimensional (1-D) silicate mesoporous molecular materials, resulting in the formation of nanocomposites. The resulting nanocomposites were characterized by UV–vis, IR, TEM, EPR and X-ray diffraction. The occluded Fe2O3 nanostructures were found to evince optical spectra and magnetic properties that were significantly different from that of bulk Fe2O3. EPR measurements indicate that the various nanocomposites (whose dimensions were controllable by the pore sizes of the silicate materials), when sufficiently loaded with small Fe2O3 nanoparticles, possess nonzero absorptions at zero applied magnetic field, as well as significant microwave absorption capacities as a function of applied magnetic field strength.