Synthesis of new compound with excellent intrinsic magnetic properties using small amounts of rare earth elements

The National Institute for Materials Science has successfully synthesized a new SmFe-based magnetic alloy, SmFe._8.8N_1.1, which has superior intrinsic magnetic properties compared to the NdFeB alloy used in neodymium magnets. Study is Published In the journal Journal of Materials.

Reducing carbon dioxide emissions is critical to achieving a sustainable society. It is necessary to improve the electrification and motor performance of many devices.

Neodymium magnets are made of Nd compound₂Fe₁₄B is widely used in electric vehicle drive motors due to its strong magnetic force.

However, neodymium magnets perform poorly at the high temperatures at which electric vehicles operate, requiring heavy rare-earth elements such as dysprosium to compensate for thermal demagnetization. Due to the significant supply chain risks associated with neodymium and dysprosium, there has been a need to explore magnetic alloys that do not use these critical elements.

Sm-Fe (1–7 series) compounds with TbCu₇-type crystal structure is expected to have higher magnetization due to the possibility of increasing Fe concentration at Sm:Fe=1:10 ratio.

However, series compounds 1–7 have not attracted much attention due to their proximity to stable Th.₂Zn₁₇-Type Sm₂Fe₁₇(2–17 series) composition, which has the highest anisotropy field.

In this study, the researchers successfully synthesized a single-crystal thin film of SmFe._8.8N_1.1 compound, which is based on the Sm-Fe(1–7 series) compound.

The magnetic properties of this compound were measured and found to be higher than Nd₂Fe₁₄P is known to be the world’s strongest magnetic material with very high field anisotropy at room temperature (approximately 22 Tesla), high saturation magnetization (1.64 Tesla) and high Curie temperature (770 Kelvin).

Previous reports on SmFe₇ The series alloy powders do not have reliable magnetic measurements, but by forming single-crystal films in this study, they demonstrated that the magnetic properties of this alloy are significantly higher than those of traditional compounds.

The magnetic properties of this alloy are higher than those of Nd₂Fe₁₄B At high temperatures, magnets made from this alloy are expected to achieve better magnetic properties without using neodymium or dysprosium, which have supply chain concerns.

Also, because this compound uses samarium, a byproduct of rare-earth purification, it promotes a balanced use of rare earths. In addition, the compound does not require expensive boron, which makes it advantageous in terms of resources and cost.

Researchers say they are developing methods to mass-produce SmFe_8.8N_1.1 Processes for compacting powder into magnets for powder and practical applications.