The polygallides: Yb₃Ga₇Ge₃ and YbGa₄Ge₂

Abstract

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 YbGa_xGe_y 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 Ga_xGe_y 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.