Recent advances in SmFe₁₂-based permanent magnets

To realize a sustainable society, 'green technology' with low (or even zero) CO₂ emissions is required. A key material in such technology is a permanent magnet because it is utilized for electric-power conversion in several applications including electric vehicles (EVs), hybrid EVs (HEVs), and turbines for wind power generation. To realize highly efficient electric-power conversion, a stronger permanent magnet than Nd-Fe-B is necessary. One potential candidate is a Fe-rich SmFe₁₂-based compound with a ThMn₁₂ structure. In this paper, the phase stability, structure, and intrinsic and extrinsic magnetic properties in both film and bulk forms are reviewed. Based on these results, a possible way to realize a strong SmFe₁₂-based permanent magnet in bulk form is discussed.