Magnetization and X-Ray Studies on (Fe_1-xNi_x)₃Ge and (Fe_1-xNi_x)_3.4Ge

Abstract

By X-ray studies, three phases, hcp, bcc and fcc are found in x ≦0.05, 0.15 ≦ x ≦0.5 and 0.6 ≦ x for (Fe 1- x Ni x ) 3 Ge and in x <0.01, 0.1 ≦ x ≦0.5 and 0.6 ≦ x for (Fe 1- x Ni x ) 3.4 Ge. The magnetization studies show a discrepancy about the boundary compositions, especially between the hcp and bcc phases. The alloys of both systems in 0.8 ≧ x are ferromagnetic. In the hcp alloys of (Fe, Ni) 3 Ge, the magnetization decreases remarkably with the substitution of nickel, while the Curie temperature stays at about 600 K. In the bcc alloys, the magnetic moment per metal and the Curie temperature lower from 1.6 µ B , 770 K of x =0.15 to 1.2 µ B , 570 K of x =0.5 for (Fe, Ni) 3 Ge, and from 1.85 µ B , 820 K of x =0.1 to 1.48 µ B , 640 K of x =0.4 for (Fe, Ni) 3.4 Ge respectively. The Curie temperature of both fcc alloys lowers from 420 K of x =0.6 to 320 K of x =0.8.