Structural and magnetic properties of iron-rich compounds in the Yb-Fe-Ga system

The iron-rich corner of the Yb-Fe-Ga phase diagram contains at least three phases. Two form in annealed samples (500 degrees C) and crystallize with either the hexagonal LuFeg(9.5) type structure (space group P6(3)/mmc) at low Ga contents (0-28 at.% Ga), or the rhombohedral PrFe7 (Th2Zn17) type structure (space group R (3) over barm) at high Ga contents (16-35 at.% Ga), while one occurs in as-cast samples at intermediate Ga contents and crystallizes with the hexagonal TbCu7 type structure (P6/mmm). As the gallium content is increased, the subcell volumes of the structures increase and the subcell ratios c/a decrease. The compounds are ferromagnetic and show magnetizations of upto sigma = 50 emu/g at 10 kOe, and magnetic ordering temperatures of up to 80 degrees C. The direction of easy magnetization is close to the basal plane. (c) 2005 Elsevier B.V. All rights reserved.