Tailored synthesis in nanoparticle permanent magnets (NPPMs)

two graphs
Top: Powder X-ray diffraction patterns Bottom: hysteresis loops of as-washed and consolidated material. R. Kuchi, T. S. Cozzini, J. V. Zaikina, I. Z. Hlova, M. J. Kramer, “Minimizing particle aggregation in Sm2Fe17N3 powders: A CaO-assisted reduction-diffusion approach”, Journal of Alloys and Compounds, 1030 (2025) 181020. https://doi.org/10.1016/j.jallcom.2025.181020

CMI researchers from Ames National Laboratory conducted the activity for this highlight

Innovation  
Direct conversion of Sm2O3 into Sm2Fe17 phase via reduction-diffusion (RD) produces Sm2Fe17N3 magnets with improved hard-magnetic properties.

Achievement  
Developed a “bottom-up” CaO assisted RD approach to minimize the particle aggregation thereby enhancing the coercivity. RD at 950°C produced high-purity (98%) Sm2Fe17N3 powders, which when sintered resulted in a bulk magnet with (BH)max = 21.1 MGOe and 88% relative density.

Significance and Impact   

  • Criticality and cost: the material is mostly Fe (~74% wt.%) and non-critical rare earth, Sm, as well as earth-abundant nitrogen.   
  • When fully developed, single grain-single particle Sm2Fe17N3-based materials  when sintered are expected to replace heavy rare earth Nd-based magnets in high performance, high temperature applications.

Hub Goal Addressed   
Microstructural engineering to reduce the need for dysprosium.