Structure and magnetic behaviors of melt-spun SmFeSiB ribbons and their nitrides

Abstract SmFe 9.3+ x Si 0.2 B 0.1 ( x =0, 0.5, 1.0) ribbons and their nitrides were prepared by melt-spinning, followed by annealing and subsequent nitriding. The structure and magnetic properties have been investigated by means of powder X-ray diffraction, vibrating sample magnetometer and Mossbauer spectroscopy. Rietveld analysis shows that the augment of Fe content gives rise to an increase of the c/a ratio and cell volume. The increasing amount of Fe atoms occupying the 2 e sites results in the change of initial structure. It is indicated that the isomer shift of 3 g and 6 l atom remains quasi-constant while the 2 e atom shows a noticeable increase with the increase of iron content, which further conforms the preferential occupation of excessive Fe atoms at this site. Consistent with Tc , the mean hyperfine field 〈 B hf 〉 has the highest value of 25.7 T when x =0.5. The hyperfine fields at different Fe sites follow the order H 2 e > H 3 g > H 6 l . The highest curie temperature of 477.68 K and the hyperfine field of 25.7 T in the as-quenched ribbons were obtained when x =0.5. Meanwhile, the highest magnetic properties of H cj =4.31 kOe, (BH) m =3.5 MGOe in the nitride powders were found.