STRUCTURE AND MAGNETIC-PROPERTIES OF HO2FE17-XGAX AND HO2FE17-XGAXC2 COMPOUNDS

The single phase compounds of Ho2Fe17-xGax and Ho2Fe17-xGaxC2 (x =, 1, 2, 3, 4, 5 and 6) with the rhombohedral Th2Zn17-type structure were prepared by melt-spinning and are-melting. Their lattice constants and the unit cell volumes derived from x-ray diffraction measurements increase linearly with increasing Ca concentration x. The Curie temperature of Ho2Fe17-xGax compounds is found first to increase and then to decrease with increasing Ga content x, attaining a maximum value of 560 K at about x = 3. For Ho2Fe17-xGaxC2, the Curie temperature is almost constant when x less than or equal to 2, then decreases rapidly with increasing Ga concentration. A monotonic decrease of the saturation magnetization with x is observed when non-magnetic Ga atom is substituted for Fe.