STRUCTURE AND MAGNETIC-PROPERTIES OF RFE11TINX (R=Y, SM, AND DY)

Single phase alloys of composition RFe11Ti with R = Y, Sm, and Dy were prepared by induction melting. The samples were nitrided by thermal cycling to 770 K, at a heating rate of 10 K/min, under an atmosphere of nitrogen in a thermopiezic analyzer (TPA). For YFe11TiN the x-ray diffraction (XRD) patterns give a = 0.8611 nm and c = 0.4802 nm for the tetragonal structure, space group I4/mmm. This represents a 3% volume expansion of the nitrogen-free unit cell. The amount of absorbed nitrogen corresponds to one nitrogen atom per formula unit indicating that RFe11TiN is a true nitrogen compound with the nitrogen atoms occupying the 2b site in the structure. The expansion of the unit cell is accompanied by a dramatic increase in the Curie temperature for all compounds.