Magnetic properties and magnetization behavior of SmCo-based magnets with TbCu7-type structure

The nanocrystalline magnets with nominal compositions of Sm1–xLuxCo6.8Zr0.2 (x=0, 0.2, 0.4, 0.6) were prepared directly by the intensive milling. The effects of Lu content on the phase structure, the magnetic properties, and magnetization behaviors were also investigated. The XRD patterns of the as-milled samples showed a single SmCo7 phase with TbCu7 structure. Lu addition was proved to result in relevant improvements in the microstructure and magnetic properties, especially in the maximum energy product (BH)max. It was shown that a higher maximum energy product and coercivity of about 17.47 kJ/m3 and 473.45 kA/m were obtained in the sample with x=0.2. From the analysis of the magnetization reversal behavior, it was found that a stronger intergrain exchange coupling interaction was observed in the samples with Lu-doping. From the studies of the coercivity mechanism, it was shown that nucleation model was the dominant magnetization reversal process at the elevated temperature.