Intermediate-Valent Yb4Rh7Sb6 with Cubic U4Re7Si6 type structure

Abstract

Abstract Yb4Rh7Sb6 was synthesized by arc-melting of the elements. The structure was refined on the basis of single crystal X-ray diffractometer data: U4Re7Si6 type, Im-3m, a = 865.9(2) pm, wR2 = 0.0557, 159 F 2 values and 10 variables. The two crystallographically independent rhodium atoms have octahedral and tetrahedral antimony coordination with Rh–Sb distances ranging from 269 to 274 pm. These polyhedra are condensed via common edges and corners, leading to a complex three-dimensional [Rh7Sb6] network. Coordination number 12 cavities within this network are filled by the ytterbium atoms. Temperature dependent magnetic susceptibility measurements show modified Curie-Weiss behavior and an experimental magnetic moment of 3.16(1)μB /Yb atom, pointing to intermediate-valent ytterbium. Magnetization measurements at 5 K give hint for short-range magnetic ordering. 121Sb Mössbauer spectra confirm the single crystallographic antimony site and antimonide character.