RUI: Carbon Encapsulated Magnetic Particles

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9405941 Parvin This research emphasizes synthesis purification, magnetic extraction, and structural and magnetic characterization of carbon- encapsulated materials. The carbon-encapsulated particles of magnetic alloys (iron-transition metal alloys, cobalt-transition metal alloys, nickel-transition metal alloys, and iron-rich rare earth alloy R2Fe17, where R is a rare earth element) are synthesized in a standard fullerene arc chamber. An efficient method extracts the magnetic particles from nonmagnetic species using interaction of magnetic moments with a magnetic field gradient. Characterization includes particle size distribution analysis using scanning electron microscopy (SEM), compositional and structural characterization using transmission electron microscopy (TEM), and x-ray diffraction analysis (XRD). The magnetic nature of the materials is studied using direct measurements of the magnetic moment of the particles over a wide range of temperature and magnetic field. Additional information concerning the magnetic nature of the iron-containing samples is determined in a series of Mossbauer spectroscopy measurements. This grant is a collaborative research project involving San Jose State University, SRI International, and E.I. duPont de Nemours. SRI international is the site for synthesis, purification, and magnetic extraction of the materials and XRD studies. SEM and TEM work is done at DuPont, and magnetometry and Mossbauer spectroscopy is carried out at San Jose State University. %%% Such materials are of interest because they combine corrosion protection from the closed carbon polyhedra and desirable ferromagnetic properties that can be tailored by the choice of particles to be encapsulated and the processing conditions. ***