The polygallides: Yb3Ga7Ge3 and YbGa4Ge2

Yb3Ga7Ge3 and YbGa4Ge2 were obtained from reactions of Yb and Ge in excess liquid gallium. The crystal structure of Yb3Ga7Ge3 was refined using X-ray and neutron diffraction data on selected single crystals. Yb3Ga7Ge3 crystallizes in the monoclinic space group C2/c with lattice constants a=12.2261(20) Å, b=10.7447(20) Å, c=8.4754(17) Å and β=110.288(30)° (neutron diffraction data). The crystal structure of Yb3Ga7Ge3 is an intergrowth of planar layers of YbGaxGey and puckered layers of (Ge)n. YbGa4Ge2 crystallizes in a modified PuGa6 structure type in the tetragonal polar space group I4cm with lattice constants a=b=5.9874(6) Å and c=15.1178(19) Å. The structure of YbGa4Ge2 is an intergrowth of puckered Ga layers and puckered GaxGey layers with Yb atoms residing within the channels formed by the connection of the two layers. Physical properties, resistivity (ρ), magnetic susceptibility (χ) and specific heat (C) were measured for Yb3Ga7Ge3. No magnetic ordering was observed. It was found that at low temperatures, ρ varied as T2 and C∝T, indicating Fermi-liquid regime in Yb3Ga7Ge3 at low temperatures.