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October 31, 2009

Nanocomposite Permanent Magnets


Schematic representation of the bottom-up assembly concept to develop high-energy nanocomposite materials for next-generation magnets. Courtesy of George Hadjipanayis, of the UD Department of Physics and Astronomy.

The University of Delaware has won a $4.4 million grant from the U.S. Department of Energy's Advanced Research Projects Agency (ARPA-E) to lead a multidisciplinary, multi-institutional research project to develop the next generation of high-performance permanent magnets The target of the project is a 2x increase (double) over the state-of-the art magnetic energy density.

According to Hadjipanayis, the strongest permanent magnets today are made from an alloy of three elements: neodymium (Nd), iron (Fe), and boron (B). Hadjipanayis was one of the three researchers who discovered the Nd-Fe-B magnets in the early 1980s.

In the new project, he and his team will be working to identify new materials that will result in magnets twice as strong as those currently in existence.

“This is the first time that such a large concerted effort will be undertaken in the U.S. on the development of high-energy magnets that involves the best expertise available in our country on this type of materials,” Hadjipanayis said.

An article in the Sept. 11, 2009, edition of the journal Science reported that the demand for Nd-Fe-B magnets is growing at about 15 percent per year, for use in products ranging from magnetic resonance imaging machines, to cell phones, headphones, and even prototype magnetic refrigerators. Yet neodymium (Nd), which is a member of the rare earth metals on the periodic table of the elements, is growing increasingly scarce.




The UD-led team will explore three different routes over the three-year project, Hadjipanayis said. The first route will be to discover new materials in tertiary rare earth-transition metal-element X systems that have not yet been explored due to synthesis difficulties such as vapor pressure, high reactivity, toxicity, or their refractory nature. The second route will be to develop materials that are free of rare earth metals and stabilized by the addition of small non-magnetic atoms (Fe-Co-X); and the third route will be to use the bottom-up approach to develop high-energy nanocomposite materials consisting of a uniform and nanoscale mixture of high anisotropy hard (Nd-Fe-B) and high magnetization soft (Fe) magnetic phases.




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