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Science 10 July 1992:
Vol. 257. no. 5067, pp. 219 - 223
DOI: 10.1126/science.257.5067.219
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Articles

Matrix-Mediated Synthesis of Nanocrystalline ggr-Fe2O3: A New Optically Transparent Magnetic Material

Ronald F. Ziolo 1, Emmanuel P. Giannelis 2, Bernard A. Weinstein 3, Michael P. O'Horo 1, Bishwanath N. Ganguly 1, Vivek Mehrotra 2, Michael W. Russell 2, and Donald R. Huffman 4

1 Xerox Webster Research Center, Xerox Corporation, Webster, NY 14580
2 Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
3 Department of Physics, State University of New York at Buffalo, Buffalo, NY 14260
4 Department of Physics, University of Arizona, Tucson, AZ 85721

A new magnetic material with appreciable optical transmission in the visible region at room temperature has been isolated as a ggr-Fe2O3/polymer nanocomposite. The synthesis is carried out in an ion-exchange resin at 60°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 100 angstroms. Optical absorption studies show that the small-particle form of ggr-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.

Submitted on April 23, 1992
Accepted on May 14, 1992


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