A. Palasyuk, A. Raja, O. Palasyuk, D. Schlagel
Ames National Laboratory,
United States
Keywords: cerium, permanent magnets, tetragonal, rare earths
Summary:
Tetragonal REFe12 compounds have attracted significant interest as permanent magnet materials since their discovery in late 1980’s. Due to low RE content and intrinsic ferromagnetism exceeding that of Nd2Fe14B, the price/performance of the 1:12 magnet is better than NdFeB. That is why these systems are considered the most suitable choice for the future development of permanent magnets. However, because of stability issues and/or lack of sufficient coercivity they are still inferior to commercial RE magnets. Historically, the most attention has been devoted to SmFe12-based materials with different M admixtures as Sm’s spin-orbit contribution to magnetic anisotropy and overall influence on magnetic exchange is very strong. In CeFe12-based materials this contribution is reduced and/or fluctuates because of the mixed valency of the Ce atoms. However, abundance and under utilization of Ce creates a long-term uninterruptible supply source, the crucial condition that is not plausible with scarce Sm and critical Nd, Dy, even if these are better suited magnetically. Therefore, potential CeFe12-type magnet will rival NdFeB and/or SmCo even if its performance is not necessarily of the same level with them, because its material cost is expected to stay low long-term. We have discovered a series of M-doped CeFe12 (M = Zr, Mo, W) materials with intrinsic magnetic properties suitable for permanent magnet development. Because of concurrent Zr/Mo and/or Zr/W doping the minimal magnetic dilution of Fe sub-lattice is achieved, which facilitates maximum total magnetic moment in the systems. Acknowledgement: This work was supported by the Critical Materials Innovation Hub, funded by the U.S. Department of Energy. The work was performed at Ames National Laboratory, operated for the U.S. Department of Energy by Iowa State University of Science and Technology.