Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation


Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applicationsthat include consumer products, transportation components, military hardware, and cleanenergy technologies such as wind turbine generators and hybrid vehicle regenerative motors.Since the 1960s, the so-called rare-earth ‘‘supermagnets,’’ composed of iron, cobalt, and rareearthelements such as Nd, Pr, and Sm, have accounted for the majority of global sales of highenergy–product permanent magnets for advanced applications. In rare-earth magnets, thetransition-metal components provide high magnetization, and the rare-earth components contributea very large magnetocrystalline anisotropy that donates high resistance to demagnetization.However, at the end of 2009, geopolitical influences created a worldwide strategicshortage of rare-earth elements that may be addressed, among other actions, through thedevelopment of rare-earth-free magnetic materials harnessing sources of magnetic anisotropyother than that provided by the rare-earth components. Materials engineering at the micronscale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding andcharacterization of nanoscale magnetic phenomena, is anticipated to result in new types ofpermanent magnetic materials with superior performance.

Laura H. Lewis & Félix Jiménez-Villacorta