title: A new complex intermetallic phase in the system Al-Cu-Ta with familiar clusters and packing principles.
abstract: The structure of hP386-Al(57.4)Cu(3.6)Ta(39.0) was determined by single-crystal X-ray diffraction analysis. It can be described as a hexagonal close-packing of two types of endohedral fullerene-like clusters with different Frank-Kasper polyhedra filling the gaps. The description of the structure as a superstructure and as a layered structure illustrates other characteristic structural building principles. The diffuse scattering, which can be observed in some of the crystals, is qualitatively well reproduced by a disorder model. A comparison with the structures of the other complex intermetallics in the system Al-Cu-Ta indicates the decisive role that Cu plays in the constitution and packing of the clusters.
authors.affiliation: Laboratory of Crystallography, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland. julia.dshemuchadse@mat.ethz.ch
authors.forename: Julia
authors.initials: J
authors.lastname: Dshemuchadse
authors.forename: Sandro
authors.initials: S
authors.lastname: Bigler
authors.forename: Arkadiy
authors.initials: A
authors.lastname: Simonov
authors.forename: Thomas
authors.initials: T
authors.lastname: Weber
authors.forename: Walter
authors.initials: W
authors.lastname: Steurer
keywords: close-packing; clusters; diffuse scattering; disorder