Intrinsic magnetic properties of Ce2(Fe, Co)14B and its modifications by Ni and Cu

Abstract

The intrinsic magnetic properties of Ce2Fe14-xCoxB (x ≤ 4.76) are studied at 25 °C using key alloys annealed at 900 °C for 25 days. The saturation magnetization (Ms) and the Curie temperature (Tc) of Ce2Fe14-xCoxB increase with Co content. However, the anisotropy field (Ha) of Ce2Fe14-xCoxB diminishes precipitously with Co content. The process of crystal structure refinement indicates that the saturation magnetization of Ce2Fe14-xCoxB is related to the site occupancy of Co atoms at different Fe atomic sites. Co atoms prefer to occupy 8j2 site, followed by 16k2, 4e and 16k1 sites sequentially. Moreover, Co atoms occupying 8j2 site are more effective leading to an increase in the Ms. The individual effects of Ni or Cu on the intrinsic magnetic properties of Ce2Fe12.98-xCo1.02NixB and Ce2Fe12.98-yCo1.02CuyB are evaluated. The maximum solid solubilities of Ni and Cu in Ce2Fe12.98Co1.02B at 900 °C are found to be 8 at.% and 0.8 at.%, respectively. Ni or Cu enhances Tc, but decreases both Ms and Ha of Ce2Fe12.98Co1.02B. The paper also discussed the combined effects of Ni and Cu on the intrinsic magnetic properties of Ce2Fe12.98Co1.02B. The Ms of Ce2Fe12.98-x-yCo1.02NixCuyB (0 ≤ x ≤ 0.41, y ≈ 0.119) increases after doping with both Ni and Cu, reaching around 155 emu/g. Meanwhile, the Ha and the Tc are measured to be near 24 kOe and 280 °C, respectively.