A novel rare earth zinc germanide, Yb2Zn3Ge3.1;: crystal structure and physical properties

A novel ternary structure type has been determined from single crystals of Yb2Zn3Ge3.1 grown from zinc flux solvent. Yb2Zn3Ge3.1 crystallizes in a novel monoclinic structure type (a = 1.5804(2) nm, b = 0.429 70(1) nm, c = 1.1524(1) nm; beta = 126.14(1)degrees) with space group C2/m, Z = 4. The large ytterbium atoms are at the centres of pentagonal pyramids formed by Zn/Ge atoms. Zinc atoms are centred in distorted triangular prisms and polyhedra around germanium atoms are related to octahedra. The void at the centre of the Zn octahedra is only partially (20%) filled by Ge atoms. There are two positions for Yb atoms in the unit cell, which contain ions with valency slightly higher than 2+, as evidenced by x-ray absorption spectroscopy and bulk magnetic measurements. The compound exhibits metallic-like electrical conductivity, and its Seebeck coefficient shows a temperature variation characteristic of metals, being, however, fairly enhanced, as expected for intermediate valence systems.