Presentation Information
[P2-56]Rapid Preparation of Sm2Fe17N3 Fine Powder by Cryo-milling
*Qiang Gao1, Dong Liang1, Hui-Dong Qian1, Tao Zhu1, Jingzhi Han1,2, Changsheng Wang1,2, Wenyun Yang1,2, Jinbo Yang1,2,3,4 (1. Institute of Condensed Matter and Material Physics, School of Physics, Peking University (China), 2. Beijing Key Laboratory for Magnetoelectric Materials and Devices (China), 3. State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University (China), 4. Peking University Yangtze Delta Institute of Optoelectronics (China))
Keywords:
Sm2Fe17N3,cryo-milling,coercivity
Samarium iron nitride (Sm2Fe17N3) permanent magnetic materials possess excellent intrinsic
magnetic properties, including a saturation magnetization of 1.54 T [1]. To reach the full potential,
the key is to increase the coercivity of the powder. Since the coercivity mechanism of Sm2Fe17N3 is
nucleation-controlled, reducing the grain size through grinding is a necessary step in preparing highperformance powders for Sm2Fe17N3 magnets [2-4].
In this study, by using the equipment named Freezer/Mill, the Sm2Fe17N3 coarse powder was
ground by cryo-milling method at liquid nitrogen temperature. After 1 minute of grinding, the
coercivity of the Sm2Fe17N3 powder went up from 1.5 kOe to 7.0 kOe, while after 4 minutes, the
coercivity reached 13.4 kOe. However, as the grinding time increased further, the coercivity began
to decrease. X-ray diffraction (XRD) results indicated that no α-Fe phase was generated during the
grinding process, and the Sm2Fe17N3 diffraction peaks broadened continuously with increasing
grinding time, showing that the liquid nitrogen conditions inhibit oxidation and thermal
decomposition during the milling process of Sm2Fe17N3, and as the grinding time increases, the
grain size of the Sm2Fe17N3 powder continuously decreases.
Meanwhile, scanning electron microscope (SEM) results showed that the sample ground for 4
minutes by cryo-milling had a similar particle size to that of the sample ground for 120 minutes by
conventional ball milling. This indicates that the material becomes more brittle at low temperatures,
making it easier to break. Compared to jet milling and ball milling methods, cryo-milling does not
require the use of conventional solvents, is more efficient, and effectively avoids heat and oxidation
issues during the grinding process. The cryo-milling method thus provides a promising approach to
fabricate high-performance Sm2Fe17N3 powder.
References
[1] Coey, J. M. D., et al. (2019). Journal of Magnetism and Magnetic Materials 480: 186-192.
[2] Liang, D., et al. (2023). AIP Advances 13(2): 025104.
[3] Ye, L., et al. (2024). Journal of Materials Research and Technology 30: 451-460.
[4] Fang, Q., et al. (2016). Journal of Magnetism and Magnetic Materials 410: 116-122.
magnetic properties, including a saturation magnetization of 1.54 T [1]. To reach the full potential,
the key is to increase the coercivity of the powder. Since the coercivity mechanism of Sm2Fe17N3 is
nucleation-controlled, reducing the grain size through grinding is a necessary step in preparing highperformance powders for Sm2Fe17N3 magnets [2-4].
In this study, by using the equipment named Freezer/Mill, the Sm2Fe17N3 coarse powder was
ground by cryo-milling method at liquid nitrogen temperature. After 1 minute of grinding, the
coercivity of the Sm2Fe17N3 powder went up from 1.5 kOe to 7.0 kOe, while after 4 minutes, the
coercivity reached 13.4 kOe. However, as the grinding time increased further, the coercivity began
to decrease. X-ray diffraction (XRD) results indicated that no α-Fe phase was generated during the
grinding process, and the Sm2Fe17N3 diffraction peaks broadened continuously with increasing
grinding time, showing that the liquid nitrogen conditions inhibit oxidation and thermal
decomposition during the milling process of Sm2Fe17N3, and as the grinding time increases, the
grain size of the Sm2Fe17N3 powder continuously decreases.
Meanwhile, scanning electron microscope (SEM) results showed that the sample ground for 4
minutes by cryo-milling had a similar particle size to that of the sample ground for 120 minutes by
conventional ball milling. This indicates that the material becomes more brittle at low temperatures,
making it easier to break. Compared to jet milling and ball milling methods, cryo-milling does not
require the use of conventional solvents, is more efficient, and effectively avoids heat and oxidation
issues during the grinding process. The cryo-milling method thus provides a promising approach to
fabricate high-performance Sm2Fe17N3 powder.
References
[1] Coey, J. M. D., et al. (2019). Journal of Magnetism and Magnetic Materials 480: 186-192.
[2] Liang, D., et al. (2023). AIP Advances 13(2): 025104.
[3] Ye, L., et al. (2024). Journal of Materials Research and Technology 30: 451-460.
[4] Fang, Q., et al. (2016). Journal of Magnetism and Magnetic Materials 410: 116-122.