Sm2Fe17N3 as a cost-effective high-performance magnet

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Hysteresis loops for Sm2Fe17 nitrided at 1 bar N2 pressure, yielding incomplete nitrogenation and low coercivity (red), and for sample nitrided at 100 bar, yielding full nitrogenation to Sm2Fe17N3 with ~ 8 kOe coercivity.
Hysteresis loops for Sm2Fe17 nitrided at 1 bar N2 pressure, yielding incomplete nitrogenation and low coercivity (red), and for sample nitrided at 100 bar, yielding full nitrogenation to Sm2Fe17N3 with ~ 8 kOe coercivity.  

CMI researchers at Ames Laboratory conducted the research for this highlight

Achievements
Attained 9 MG-Oe energy product in Sm2Fe17N3 via development of  low-temperature high-pressure Sm2Fe17 nitrogenation protocol that achieves full, 3 N atoms per formula unit - essential for permanent magnet performance. Determined that maximum solubility limit of La in Sm2Fe17 is 25 at.%

Significance and impact

  • Criticality and cost: mostly Fe (~74% wt.%), and abundant, non-critical rare earths – Sm, La and Ce.
  • Strong competitor to Nd-based magnets with comparable or better permanent magnet properties.

Details and next steps
Increase thermal stability by substitutions with La and/or Ce, as predicted by D. Parker at al., Phys. Rev. Appl., 2018, and/or doping with transition metals and p-block elements to enable consolidation by sintering