Novel Magnetic Nanoparticles and Nanoflakes

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TECHNICAL SUMMARY: The proposed research is focused on the synthesis and characterization of magnetically hard rare earth-transition metal (R-TM) nanoparticles and nanoflakes with a size below 100 nm. The ultimate goal is to use these nanoparticles together with magnetically soft Fe(Co) nanoparticles to develop anisotropic nanocomposite magnets with very high energy products. Nanoparticles /nanoflakes based and the RCo5, R2(Fe,Co)17 and R2Fe14B crystal structures will be synthesized by the novel surfactant-assisted ball milling technique which has been proven to be capable of producing separate and magnetically anisotropic nanoparticles. The proposed experiments will lead to a better understanding of the mechanism(s) of nanoparticle/nanoflake formation that would allow the preparation of larger amounts of nanoparticle/nanoflake powders with uniform and controlled size which are needed for the study of the fundamental and technological properties. The proposed studies on nanoparticles with particle sizes in the range of 4-100 nm, will enable investigations of particle size and surface effects on the crystal structure, the magnetic structure and the fundamental and hard magnetic properties of the particles. The newly developed nanoparticles/nanoflakes with tailored properties will then be assembled together with magnetically soft Fe(Co) nanoparticles via a "bottom-up" approach to form aligned nanostructures which may lead to the development for the first time of highly anisotropic nanocomposite permanent magnets with very high energy products.NON-TECHNICAL SUMMARY: The proposed study is aimed at the fabrication of rare-earth alloy (SmCo5 and Nd2Fe14B) powders with size below a few millionths of an inch, and the study of their magnetic properties as a function of particle size. The rare earth alloy nanopowders with the best properties will then be used together with Fe(Co) nanopowders in a bottom-up approach to develop high performance composite magnets with strength significantly higher than those of the best available Nd-Fe-B magnets. Furthermore, the amount of rare earth in these composite magnets will be lower by 30-40% and this will decrease the future dependency on these scarce rare earths metals. The high performance magnets will lead to lower-cost, more efficient energy and power-dense devices that will result in a substantial reduction in our nation's dependence upon foreign sources of fossil fuels. The project will also provide education and training of students in the important and critical areas of permanent magnets and nanoscale magnetism which are vital to the U.S. economy and defense.