Magnetic and X-Ray Studies of Iron-Germanium System II. Phase Diagram and Magnetism of Each Phase

Abstract

Constitution of iron-germanium system is discussed based on x-ray and magnetic studies, and a new phase diagram is proposed. Fe solid solution (α) ranges up to 20.4 at.% Ge at 710°C and to 21.3 at.% Ge at 520°C. Homogeneity range of the most iron rich compound ( ε above 700°C and ε 1 below) are 23.8–26 at.% Ge at 710°C ( ε ) and 24.2–25.8 at.% Ge at 580°C ( ε 1 ). At 50 at.% Ge, ξ phase has a narrow range below 700°C. In α (b. c. c.) solid solution of iron, the saturation magnetization and Curie point decrease to 150 emu/g and 885°K respectively. Crystal structures of ε and ε 1 phases are Ni 3 Sn(D0 19 ) and Cu 3 Au(L1 2 ) type, and the saturation magnetization of both phases is about 150 emu/g, while the Curie points are 650°K for ε and 760°K for ε 1 . ζ Phase has CoSn (B35) type of structure and is paramagnetic, the moment being 2.8µ B /Fe. Magnetic interaction and magnetic structures are also discussed.