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Nanosized Anisotropic Sm-Fe-N Particles with Metastable TbCu7-Type Structures Prepared by an Induction Thermal Plasma
Yusuke Hirayama1, Jian Wang1, Masaya Shigeta2
1National Institute of Advanced Industrial Science and Technology, 4-205, Sakurazaka, Moriyama, Nagoya 463-8560, Japan.
Nanomaterials (Basel, Switzerland)
|July 12, 2025
Summary
Researchers developed anisotropic samarium-iron-nitrogen (Sm-Fe-N) nanoparticles using a low-oxygen induction thermal plasma process. These particles show potential to surpass existing permanent magnets, achieving high alignment for advanced magnetic applications.
Area of Science:
- Materials Science
- Nanotechnology
- Magnetism
Background:
- Samarium-based (Sm) compounds with the TbCu7-type structure show promise as high-performance permanent magnets, potentially exceeding Neodymium-Iron-Boron (Nd2Fe14B).
- Limited methods for preparing anisotropic magnetic particles hinder the full exploitation of these Sm-based compounds.
- Developing anisotropic Sm-Fe-N ultrafine particles is crucial for advancing permanent magnet technology.
Purpose of the Study:
- To prepare metastable TbCu7-type phases of anisotropic Sm-Fe-N ultrafine particles.
- To investigate the magnetic properties and alignment of these novel nanoparticles.
- To understand the formation mechanism of Sm-Fe nanoparticles during the plasma process.
Main Methods:
- Utilized the low-oxygen induction thermal plasma (LO-ITP) process for particle synthesis.
- Employed X-ray diffraction (XRD) for structural analysis and phase identification.
- Applied external magnetic fields for nanoparticle alignment and pole figure measurements for quantitative estimation.
Main Results:
- Successfully prepared TbCu7-type Sm-Fe alloy nanoparticles with a c/a value of 0.8419 and an Fe/Sm atomic ratio of ~8.5.
- Achieved a high degree of alignment (91 ± 2%) in nitrogenated Sm-Fe-N nanoparticles, confirming anisotropic magnetic properties.
- Numerical analysis revealed Sm condensation persists at low temperatures due to vapor pressure differences, leading to a Sm concentration of 9-12 at%.
Conclusions:
- The LO-ITP process enables the production of anisotropic Sm-Fe-N ultrafine particles with potential as advanced permanent magnets.
- Optimizing LO-ITP parameters can facilitate the preparation of single-phase TbCu7-type Sm-Fe-N particles.
- The findings pave the way for exploiting the full potential of Sm-based permanent magnets.
