MAGNETIC-PROPERTIES OF NOVEL COMPOUNDS R-3(FE,CR)(29)X-Y (R = ND, SM AND X = N, C)

The novel ternary rare-earth iron-rich interstitial compounds R-3(Fe,C r)(29)X-y (R=Nd, Sm and X=N, C) with the monoclinic Nd-3(Fe,Ti)(29) st ructure have been successfully synthesized. Introduction of the inters titial nitrogen and carbon atoms led to a relative volume expansion De lta V/V of about 6% and an enhancement of Curie temperatures T-c about 268 K for the nitride and about 139 K for the carbide, respectively. The Nd3Fe24.5Cr4.5Xy compounds have a planar anisotropy at room temper ature. A first-order magnetization process (FOMP) with critical field B-cr=4.4 T and 3.1 T at room temperature were observed for the Nd-nitr ide and carbide compounds, respectively. The Sm3Fe24Cr5Xy compounds we re found to have a large uniaxial anisotropy of about 18 T at 4.2 K an d about 11 T at 293 K. A FOMP with B-cr=2.3 T was also observed in the Sm-nitride compounds at 4.2 K. Magnets with coercivity of mu(oj)H(c) similar to 0.8 T at 293 K has been successfully developed from the Sm3 Fe24Cr5Xy (X=N and C) phases. (C) 1997 Elsevier Science S.A.