STRUCTURAL AND MAGNETIC-PROPERTIES OF ARC-MELTED RFE(10)V(2) CARBIDES(R=Y OR SM)

Using x-ray diffraction, powder neutron diffraction, high-field magnet ization measurement and thermomagnetic analysis, we have studied the s tructural and magnetic properties of RFe(10)V(2)C(0.5) alloys (R = Sm or Y) made by are melting, in which the carbon was added using Fe-C al loy. Both samples are found to be nearly single phase with ThMn12-type structure and with a small amount of alpha-Fe phase (less than 4 wt%) . The neutron diffraction of the Y-containing compound indicates that the real composition of the main phase is Y(Fe9.87V1.90C0.23)C-0.27. a nd that the carbon atoms occupy not only the interstitial 2b site but also the substitutional 8i site. The Fe moments of the 8i site as well as the 8j site are found to be reduced in the Y(Fe9.87V1.90C0.27)C-0. 27 compound compared with its carbon-free counterpart. The decrease in the Fe moment at the 8j site is due to the surrounding interstitial c arbon atoms, while the decrease in the Fe moment at the 8i site is asc ribed to the surrounding substitutional carbon atoms as nearest neighb ours. The high-field magnetization measurements indicate that the anis tropy held of SmFe10V2C0.5 and YFe10V2C0.5 are slightly higher than th ose of SmFe10V2 and YFe10V2, respectively. In SmFe10V2C0.5, the magnet ization curve in the hard direction at 4.2 K shows a first-order-magne tization-process (FOMP)-like or quasi-FOMP-like transition.