SC11-XYBXGE10 (X-APPROXIMATE-TO-5) - A SUBSTITUTION VARIANT WITH HO11GE10 TYPE-STRUCTURE SHOWING PARTIAL ORDER ON THE RARE-EARTH SITES

Sc11-xYbxGe10 (x approximate to 5) is a new ternary germanide which is in equilibrium with binary Sc11Ge10 at 600 degrees C. Both phases cry stallize with the tetragonal Ho11Ge10 structure type. The ternary phas e (space group I4/mmm, a=1.0505(7), c=1.587(2) nm) was investigated by single crystal X-ray diffraction, and found to contain four rare eart h sites of which one (CN=15) is fully occupied by Sc, and the other th ree (CN=15, 17, 17) by a one-to-two mixture of Sc and Yb. The partial ordering on the rare earth sites is the first such observed for this s tructure type.