MOSSBAUER EVIDENCE FOR UNIAXIAL MAGNETIC-ANISOTROPY IN MELT-SPUN SM2FE17CX FOR X-GREATER-THAN-OR-EQUAL-TO-0.5

The Fe-57 Mossbauer study of melt-spun and subsequently annealed Sm2Fe17C(x) compounds provided evidence for the onset of uniaxial magnetic anisotropy even for x = 0.5. The jumps in the hyperfine field values in going form x = 0 to x = 0.5 can be correlated with the change in the magnetic anisotropy from planar in Sm2Fe17 to uniaxial in Sm2Fe17C0.5. From the average hyperfine field at room temperature, values of the iron average moment of 1.9-mu-B were obtained for Sm2Fe17C1.5, corresponding to a theoretical maximum energy product of an ideal anisotropic magnet made from this material of about 400 kJ m-3 (50 MGOe). Substitutions of cobalt for iron influenced only slightly the iron average field at 77 K for Sm2Fe17C(x) with x = 1-1.5. However, owing to the strong rise of the Curie temperature, an increase of the average hyperfine field and moment up to 30.6 T and 2.0-mu-B respectively was found at room temperature for Sm2Fe14Co3C.