Magnetic properties of Sm 2Fe 17N y with Al substituted for Fe

Abstract

By means of X-ray diffraction analysis, it is shown for x < 0.4 that all the interstitial Sm 2(Fe 1− x Al x ) 17N y nitrides and the parent compounds crystallize with Th 2Zn 17-type structure. The lattice constants of the parent compounds increase linearly with Al concentration. The introduction of nitrogen atoms leads to a further increase in the lattice constants, but the increase becomes smaller with increasing Al concentration; this can be related to the fact that the nitrogen content introduced into the parent compounds decreases nearly linearly with increasing Al concentration. The dependence on composition of T C of the parent compounds exhibits a maximum, whereas T C of the nitrides decreases monotonically with Al content from 750 K for x = 0 to 313 K for x = 0.4. The introduction of nitrogen leads to enhancement of the average magnetic moment of Fe in Sm 2Fe 17, whereas the substitution of Al for Fe leads to a decrease in the average magnetic moment of Fe in both the nitrides and the parent compounds. The anisotropy field B a of nitrides is almost independent of the Al concentration for x ≤ 0.3, then decreases very fast and becomes zero at about x = 0.4.