Research and Development of Interstitial Compounds

The interstitial rare earth-iron compounds exhibiting a variety of magnetocrystalline anisotropies, large saturation magnetization, and high Curie temperature provide the basis for high-performance magnetic materials. In this paper, a manufacturing process for mass production of anisotropic magnetic powders has been successfully developed for Nd(Fe, M)₁₂N (NdFeN) and Sm₂Fe₁₇N₃ (SmFeN) compounds with uniaxial anisotropy. The magnetic powders of Nd(Fe, M)₁₂N have maximum energy products [(BH)_max] around 22 MGOe. The calendar magnets of NdFeN show the rolling anisotropy and have a (BH)max up to 5.9 MGOe with excellent mechanical properties and good anticorrosion ability. The (BH)max of SmFeN magnetic powders is up to 41 MGOe, which is favorable for fabricating high-performance injection magnets and extrusion magnets. On the other hand, it was found that cone or planar anisotropic R₂Fe₁₇N_x (R = Ce, Pr, Nd) and paraffin composites can improve the Snoek limit and exhibit a high microwave reflection loss of up to -35 dB at about 14 GHz, presenting an advantage for application as a high-performance thin-layer microwave absorber. These results open up broad prospects for technological applications using interstitial modified compounds.