# Fileset

[IEEE Magnetic Frontiers.docx](https://mdr.nims.go.jp/filesets/1f8e9f57-e6a4-490a-88bc-c1e975536109/download)

## Creator

[SEPEHRI AMIN Hossein](https://orcid.org/0000-0002-7856-7897)

## Rights

[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[High Performance Permanent Magnets;  How to solve element criticality while considering new demands?](https://mdr.nims.go.jp/datasets/22a0ef87-9b43-4614-8176-5e19f11a71b8)

## Fulltext

High Performance Permanent Magnets; How to solve element criticality while considering new demands?H. Sepehri-Amin* 1National Institute for Materials Science, 1-2-1 Sengen, *h.sepehriamin@nims.go.jpPermanent magnets are widely used in green energy conversion and play an important role in achieving net-zero CO2 emissions. In order to maintain sustainable production of permanent magnets in the long term, it is necessary to eliminate the dependence of permanent magnets on critical elements such as Dy and to diversify the use of rare earths while maintaining their performance close to their theoretical limits. In this talk, we will first present our fundamental research on why the coercivity of permanent magnets with different microstructural features are far below their theoretical limits (magnetic anisotropy field) [1,2]. We will present several examples in different permanent magnet systems of how defect engineering can lead to an enhancement of the extrinsic magnetic properties, in particular the coercivity. This will be demonstrated for Dy-free Nd-Fe-B based permanent magnets and Nd-lean (Nd,Ce)-Fe-B magnets.  Furthermore, we will discuss the potential of SmFe12 based compounds and the current challenges to realize these materials as new permanent magnets. We will show our recent successes in microstructure engineering of these materials, both in magnetic thin films and in bulk magnetic materials, to realize sufficiently large coercivities above 1.4 T supported by machine learning [3,4]. Based on detailed microstructural characterizations, magnetic thin films and micromagnetic simulations, the optimal microstructure that can lead to higher coercivity and remanent magnetization in the SmFe12-based magnets will be discussed. Finally, we will discuss future strategies in the development of permanent magnets that need to be considered in view of the emergence of new applications [5].[1] J. Li, H. Sepehri-Amin, T. Ohkubo, K. Hono, Phys. Rev. B 105 (2022) 174432.[2] X. Tang, J. Li, H. Sepehr-Amin et al. NPG Asia Mater. 15 (2023) 50.[3] H. Sepehri-Amin et al. Scripta Mater. 242 (2024) 119869.[4] A. K. Srinithi, X. Tang, H. Sepehri-Amin, J. Zhang, T. Ohkubo, K. Hono, Acta Mater. 256 (2023) 119111.[5] K. Uchida, T. Hirai, F. Ando, H. Sepehri-Amin, Adv. Energy Mater. 14 (2024) 247011.