Structural and intrinsic magnetic properties of (Sm 1−xNd x) 2Fe 17N ≈2.7 and Sm 1−xNd x) 2(Fe 1−zCo z) 17N ≈ 2.7

Abstract

Formation and magnetic properties of interstitital (Sm 1−xNd x) 2Fe 17N ≈2.7 nitrides are reported. The thermal stability of Sm 2Fe 17N ≈2.7 is not much affected by substituting Nd for Sm, whereas the Curie temperature is slightly decreased from 746 K for x = 0 to 725 K for Nd 2Fe 17N ≈2.7. The saturation polarization increases from 1.52 T for x = 0 to 1.60 T for x = 1. The strong uniaxial anisotropy of Sm 2Fe 17N 2.9 ) H A = 21.0 T at room temperature) is significantly reduced by substituting Nd for Sm due to the strong planar anisotropy of Nd 2Fe 17N ≈2.7 ( K 1 = −6.8 MJ/m 3 and K 2 = 0.8 MJ/m 3). For intermediate Nd contents the easy magnetization direction changes from the c-axis over an easy cone to the basal plane with decreasing temperature. By substituting Co for Fe the decrease of the anisotropy field can be partly balanced and the saturation polarization and the Curie temperature are further increased, giving H A = 14.8 T, J s = 1.57 T and T C = 835 K for (Sm 0.7Nd 0.3) 2(Fe 0.8Co 0.2) 17N ≈2.7.