Novel ytterbium-zinc-silicides and germanides grown from zinc-flux

Novel ternary ytterbium-zinc-silicides and germanides have been synthesized using pure zinc metal as a flux-solvent. The new compounds, YbZn2Si2 and YbZn2Ge2 crystallize with the BaAl4 or ThCr2Si2-type. Yb(Zn,Si)(2) and Yb(Zn,Si)(2-x) crystallize with the ThSi2 and the GdSi2-x type, respectively. Crystal properties were characterized using X-ray single crystal analysis via Gandolfi and Weissenberg film techniques, by flat specimen X-ray powder diffractometry and in some cases by automatic four circle X-ray single crystal diffractometry. Depending on the heating and cooling program in the synthesis, various lattice parameter values were obtained suggesting the existence of homogeneity regions. Both the Yb-Zn-silicides and the germanide show a temperature independent Pauli-type paramagnetic behaviour down to liquid He temperature consistent with the XAS-measurements revealing an Yb2+ ground state. (C) 1998 Elsevier Science S.A.