Phase modification and magnetic energy product enhancement of PrCo5-based nanomaterials due to carbon addition

The magnetic properties, phase evolution, microstructure, and magnetic domain structure of melt-spun PrCo5-xCx and PrCo5Cy (x = 0-0.4 and y = 0-0.4) flakes are compared. Binary PrCo5 flakes exhibit low intrinsic coercivity (H-i(c)) of 3.2 kOe and thus a low magnetic energy product ((BH)(max)) of 4.4 MGOe, which is attributed to the coarse grains. By doping with proper amounts of C, the well-modified phase composition and uniformly refined microstructure and magnetic domains enhance the magnetic properties remarkably. Different phase compositions found for two approaches for doping PrCo5 with C dominate the magnetic properties in addition to the fine microstructure. In PrCo5-xCx (x = 0-0.4) flakes, the 2:17 phase suppressed by doping with C contributes to coercivity increase, and the largest H-i(c) of 13.5 kOe with (BH)(max) = 8.8 MGOe is obtained for PrCo4.9C0.1 flakes. For higher x, the formation of the 5:19 phase slightly reduces H-i(c) to 7.2-8.8 kOe and (BH)(max) to 7.2-8.0 MGOe. In contrast, in the PrCo5Cy (y = 0-0.4) series flakes, the increased amount of the 2:17 phase and the strengthened exchange coupling effect resulting from the refined microstructure caused by doping with a proper amount of C result in large (BH)(max) of 11.8 MGOe with H-i(c) of 5.0 kOe for PrCo5C0.3 flakes.