MAGNETIC-PROPERTIES OF THE BOROCARBIDES R3BXC4-X (R=GD, HO, X-LESS-THAN-1) WITH SC3C4-TYPE STRUCTURE

X-ray powder diffractograms proved the occurrence of the Sc3C4-type of structure for Ho3BxC4-x for 0 less than or equal to x less than or eq ual to 0.8, whereas the gadolinium containing compound could only be s tabilized by adding 7.5 at.% boron to the sample. Ac as well as de mag netic susceptibilities of the pure binary Ho3C4 exhibit an antiferroma gnetic transition at a Neel temperature of T-N=10 K, followed by a met amagnetic transition in external fields of H>0.1 T. The holmium boroca rbides undergo ferromagnetic transitions below T-C=35 K. The feature o f the magnetization curves is reminiscent of a system composed of narr ow domain walls. The gadolinium-borocarbide also orders ferromagnetica lly at a Curie temperature of T-C=159 K. (C) 1998 Elsevier Science S.A . All rights reserved.