Structure cristalline du composé intermétallique Ni18Ge12

Abstract

Single crystals of octadecanickel dodecagermanide were grown by chemical transport reaction. The intermetallic compound crystallizes in a superstructure of the hexagonal NiAs type (B8 type). All atoms in the asymmetric unit lie on special positions except one Ni atom (two Ni atoms have site symmetry -6.. and another one has site symmetry .2. while the Ge atoms have site symmetries 32.,m.. and 3..). In the structure, the Ni atoms are arranged in 11- or 13-vertex polyhedra (CN = 11–13). The coordination polyhedra of the Ge atoms are bicapped square antiprisms (CN = 10) or 11-vertex polyhedra (CN = 11). The structure exhibits strong Ge...Ni interactions, but no close Ge...Ge contacts are observed. The Ni atoms with CN = 13 form infinite chains along [001] with an Ni—Ni distance of 2.491 (2) Å.