MAGNETIC-PROPERTIES AND THERMAL-STABILITY OF SM2FE17NX WITH INTERMEDIATE NITROGEN CONCENTRATIONS

The existence of interstitial Sm2Fe17Nx with intermediate nitrogen contents (0 less-than-or-equal-to x less-than-or-equal-to 2.94) is revealed by a continuous increase of the unit cell volume, the Curie temperature, the saturation polarization and the anisotropy field with increasing N concentration. The thermal stability of Sm2Fe17Nx increases also with increasing x. The anisotropy constants K1 and K2 at room temperature were deduced by fitting magnetization curves of oriented powders. The easy magnetization direction changes from the basal plane (x = 0) via an easy cone (delta = 24-degrees for x = 0.4) to the c-axis (x greater-than-or-equal-to 0.55). The intrinsic magnetic properties of Sm2Fe17N2.94 were found to be T(c) = 473-degrees-C, J(s) = 1.51 T and H(A) = 21.0 T where K1 = 8.4 and K2 = 2.1 MJ/m3.