Enhanced compensation effect of Gd and Dy in 2:17-type SmCo magnets

The maximum magnetic energy product ((BH)_max) of 2:17-type SmCo magnets with low temperature coefficient (α), prepared by partially substituting Sm with heavy rare-earth elements (HREs), are lower than that of conventional magnets. Optimizing their magnetic properties by harnessing complementary advantages of different HREs is an effective approach that warrants further study. This study unveils an enhanced compensation effect of co-doping Gd and Dy elements in SmCo magnets, which becomes significant as the total content of Gd and Dy increases. Specifically, when the co-doping level of Gd and Dy reaches 10.3 wt%, there is a significant improvement of 71 % in (BH)_max compared to doping with 10.3 wt% Dy alone, while maintaining a comparable α value. Microstructure and microchemistry analysis, along with first principles calculations reveal that this effect is closely associated with the enrichment of Dy in cell 2:17R phases. This finding holds significance for designing temperature-stable SmCo magnets.