EFFECT OF NITROGEN ON THE STRUCTURAL AND MAGNETIC-PROPERTIES OF INTERMETALLIC COMPOUNDS WITH THE THMN12 STRUCTURE

The effects of nitrogen uptake on the structural and magnetic properties of RFe12-xTx alloys have been studied. Several interstitial nitrides with composition RFe12-xTxNy (R = Nd and Sm and T = Ti and V) were prepared by heat treating fine powders of RFe12-xTx 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 NdFe12-xTxNy and from "uniaxial" to "planar" for SmFe12-xTxNy.