title: Structure cristalline du composé intermétallique Ni18Ge12.
abstract: Single crystals of octa-deca-nickel dodeca-germanide were grown by chemical transport reaction. The inter-metallic compound crystallizes in a superstructure of the hexa-gonal 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 anti-prisms (CN = 10) or 11-vertex polyhedra (CN = 11). The structure exhibits strong Ge⋯Ni inter-actions, 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.
authors.affiliation: Université Houari-Boumedienne, Faculté de Chimie, Laboratoire Sciences des matériaux, BP 32 El-Alia 16111 Bab-Ezzouar, Algérie.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Kars
authors.affiliation: Centro de Microscopia Electrónica, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Adrian Gómez
authors.initials: AG
authors.lastname: Herrero
authors.affiliation: Centre de Diffractométrie X, Sciences Chimiques de Rennes, UMR 6226 CNRS Université de Rennes 1, Campus de Beaulieu, Avenue du Général Leclerc, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Roisnel
authors.affiliation: Université Houari-Boumedienne, Faculté de Chimie, Laboratoire Sciences des matériaux, BP 32 El-Alia 16111 Bab-Ezzouar, Algérie.
authors.forename: Allaoua
authors.initials: A
authors.lastname: Rebbah
authors.affiliation: Departomento Inorgánica, Facultad C.C. Químicas, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: L Carlos
authors.initials: LC
authors.lastname: Otero-Diáz
keywords: B8-type substructure; Ge⋯Ni inter­actions; crystal structure; inter­metallic compound; nickel germanide
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