TbNb6Sn6: the first ternary compound from the rare earth–niobium–tin system

摘要

The title compound, terbium hexa­niobium hexastannide, TbNb6Sn6, is the first ternary compound from the rare earth–niobium–tin system. It has the HfFe6Ge6 structure type, which can be analysed as an inter­growth of the Zr4Al3 and CaCu5 structures. All the atoms lie on special positions; their coordination geometries and site symmetries are: Tb (dodeca­hedron) 6/mmm; Nb (distorted icosa­hedron) 2mm; Sn (Frank–Caspar polyhedron, CN = 14–15) 6mm and m2; Sn (distorted icosa­hedron) m2. The structure contains a graphite-type Sn network, Kagome nets of Nb atoms, and Tb atoms alternating with Sn2 dumbbells in the channels.