Crystal structure and hard magnetic properties of TbCu7-type Sm0.98Fe9.02–xGax nitrides

The compound Sm0.98Fe9.02–xGaxNδ (x=0, 0.25, 0.5, 0.75, 1) were prepared by melt-spun method and subsequent annealing and nitriding. The Rietveld analysis showed that the lattice expansion played an important role in improving the Curie temperature. An obvious development of the Curie temperature was obtained with the increased Ga content from x=0–1 (ΔTc=90 °C). The optimum coercivity of nitrides was obtained at x=0.25 with the value Hcj=652 kA/m (8.15 kOe) after annealing, which corresponded to a reasonable distribution of grain sizes of both TbCu7-type SmFe9NΔ and α-Fe. However, an excess of Ga doping might lead to an abnormal growth of α-Fe, which in turn deteriorated the magnetic properties. It was concluded that a moderate Ga content was very effective in raising the coercivity and Curie temperament in the TbCu7-type Sm-Fe-N.

Graphical AbstractX-ray powder diffraction patterns of melt-spun Sm0.98Fe9.02–xGax (x=0, 0.25, 0.5, 0.75, 1) alloys prepared at the wheel speed of 50 m/sFigure optionsDownload as PowerPoint slide