Crystal Growth and Properties of YbCuGa3: First Monoclinic System in the RETX3 Family

High quality single crystals of YbCuGa3 were obtained from the reaction of Yb and Cu in excess liquid gallium as a solvent at 1173 K. The crystal structure of YbCuGa3 was refined using X-ray diffraction data on a selected high quality single crystal. YbCuGa3 crystallizes in a new structure type in the monoclinic space group C2/m and lattice constants a = 11.6891(8) Å, b = 4.162(4) Å, c = 8.3196(7) Å, and β = 110.834(5)°. The crystal structure of YbCuGa3 is composed of eight capped hexagonal prism cages [Yb4Cu4Ga12] occupying one ytterbium atom in each ring, which is shared through the edge Cu and Ga atoms along the ab plane resulting in a three-dimensional network. The magnetic susceptibility of YbCuGa3 was investigated in the temperature range 2–300 K obeying the Curie–Weiss law above 130 K and the experimentally measured magnetic moment indicates mixed valent ytterbium and a deviation in inverse susceptibility data below 130 K. Electrical conductivity measurements show that the compound exhibits metallic nature.