Indexed on: 16 Aug '04Published on: 16 Aug '04Published in: Monatshefte für Chemie - Chemical Monthly
The ternary rare earth metal-magnesium-germanides RE2Ge2Mg (RE=Y, La–Nd, Sm, Gd, Tb) were synthesized by reaction of the elements in sealed tantalum tubes in a water-cooled sample chamber of an induction furnace. The germanides were characterized through their X-ray powder patterns. The structures of Ce2Ge2Mg and Pr2Ge2Mg were refined from X-ray single crystal diffractometer data: Mo2FeB2 type, P4/mbm, a=750.6(1), c=442.4(1) pm, wR2=0.0378, 386 F2 values, 12 variable parameters for Ce2Ge2Mg, and a=745.7(1), c=439.2(1) pm, wR2=0.0462, 448 F2 values, 12 variable parameters for Pr2Ge2Mg. The lanthanum compound shows a homogeneity range La2+xGe2Mg1−x. The structure of a single crystal with x=0.249(5) was refined from X-ray data: a=770.52(7), c=447.4(1) pm, wR2=0.0481, 322 F2 values, 13 variable parameters. The RE2Ge2Mg structures can be considered as a 1:1 intergrowth of CsCl and AlB2 related slabs of compositions REMg and REGe2.