High Anisotropy Magnetic Nanoparticles and Nanocomposites

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A major objective of the grant is to fabricate nanoparticles for high moment high coercivity ferromagnets with emphasis on CoPt, FePt and rare earth intermetallic compounds. The nanoparticles will be used to fabricate special nanocomposite structures with tailored properties for high performance permanent magnets and high-density recording. The influence of particle size, particle separation, and matrix material on magnetic and hysteresis properties will be studied using various experimental techniques such as transmission electron microscopy, SQUID magnetometry, Mossbauer spectroscopy, Lorentz microscopy, synchrotron radiation and neutron diffraction. The nucleation and growth of compound nanoparticles and their phase transformations will be studied by both experiment and modeling during in-situ annealing through light absorption. The in-situ heat treatment of the particles is expected to transform their structure into the desired phase before they are deposited onto the substrate, avoiding the undesirable effects of alloying and oxidation. The proposed nanocomposite structures, along with their technological importance, will serve as model structures for the testing and refinement of existing hysteresis models that will help the development of new advanced magnets. The proposed work on the particle size-chemical composition-structure-properties relationship in nanoparticles will benefit the technological development of these nanocomposite materials. The high anisotropy of the proposed alloy/compound systems will make it possible to fabricate thermally stable nanoparticles with a size in the range of 1-4 nm.The training of students includes nanoparticle synthesis, structural and microstructural characterization by x-ray diffraction and electron microscopy and magnetic measurement techniques. The students further enrich their education through participation in special international workshops on nanostructured materials organized by the PI. The interdisciplinary nature of the proposed work will establish collaborations with other departments, industry, and national labs, and would help the students broaden and enrich their knowledge base. The proposed program will strengthen the established partnership with the Delaware Department of Education, school districts, business and industry, and the university community at large to help K-12 math and science teachers implement new content and performance-based standards in their classrooms. The students will be encouraged and supported to attend workshops and meetings to disseminate their research findings to the community.