Effect of the substitution of Ga on the structure and magnetic properties of Dy2Fe17compound

Dy2Fe17-xGax (x = 0, 1, 2, 3, 4, 5 and 6) compounds were prepared by arc melting. These compounds are of single phase, having a hexagonal Th2Ni17-type structure for x = 0 and rhombohedral Th2Zn17-type structure for x ≥ 1. The substitution of Ga for Fe in the Dy2Fe17 leads to a linear increase of unit-cell volumes. The saturation magnetization Ms at 1.5 K is found to decrease linearly with increasing Ga concentration, from 65 emu/g for x = 0 to 5 emu/g for x = 6; and the Fe magnetic moment μFe is almost independent of Ga concentration. The Curie temperature TC is found first to increase with increasing Ga content x, and goes through a maximum value of 559 K at about x = 3, then decreases. The sharp increase of TC at lower Ga content may result from the increase of unit cell volumes. Dy2Fe17-xGax compounds with x ≤ 5 exhibit easy plane anisotropy at room temperature, and those with x = 6 possess easy-axis.