MATRIX-MEDIATED SYNTHESIS OF NANOCRYSTALLINE GAMMA-FE2O3 - A NEW OPTICALLY TRANSPARENT MAGNETIC MATERIAL

A new magnetic material with appreciable optical transmission in the visible region at room temperature has been isolated as a gamma-Fe2O3/polymer nanocomposite. The synthesis is carried out in an ion-exchange resin at 60-degrees-C. Magnetization and susceptibility data demonstrate loading-dependent saturation moments as high as 46 electromagnetic units per gram and superparamagnetism for lower loadings where particle sizes are less than 1 00 angstroms. Optical absorption studies show that the small-particle form of gamma-Fe2O3 is considerably more transparent to visible light than the single-crystal form. The difference in absorption ranges from nearly an order of magnitude in the "red" spectral region to a factor of 3 at 5400 angstroms. The magnetization of the nanocomposite is greater by more than an order of magnitude than those of the strongest room-temperature transparent magnets, FeBO3 and FeF3.