Effect of nitrogen on the structural and magnetic properties of intermetallic compounds with the ThMn12 structure

Abstract

The effects of nitrogen uptake on the structural and magnetic properties of RFe_12−xT_x alloys have been studied. Several interstitial nitrides with composition RFe_12−xT_xN_y (R=Nd and Sm and T=Ti and V) were prepared by heat treating fine powders of RFe_12−xT_x alloys in N₂ gas. Preliminary results show the following observations: (1) The ThMn₁₂ structure of the original compounds is retained with the addition of nitrogen but with increased lattice constants (a and c). (2) The Curie temperature is greatly enhanced by about 150–175 K. (3) The character of magnetic anisotropy is changed from ‘‘weak uniaxial’’ type to ‘‘strong uniaxial’’ type for NdFe_12−xT_xN_y and from ‘‘uniaxial’’ to ‘‘planar’’ for SmFe_12−xT_xN_y.