title: Large, larger, largest--a family of cluster-based tantalum copper aluminides with giant unit cells. I. Structure solution and refinement.
abstract: This is the first of two parts, where we report the structure determination of a novel family of cluster-based intermetallic phases of unprecedented complexity: cF444-Al(63.6)Ta(36.4) (AT-19), a = 19.1663 (1) A, V = 7040 A3, cF(5928-x)-Al(56.6)Cu(3.9)Ta(39.5), x = 20 (ACT-45), a = 45.376 (1) A, V = 93,428 A(3) and cF(23,256-x)-Al(55.4)Cu(5.4)Ta(39.1), x = 122 (ACT-71), a = 71.490 (4) A, V = 365,372 A3. The space group is F43m in all three cases. These cluster-based structures are closely related to the class of Frank-Kasper phases. It is remarkable that all three structures show the same average structure that resembles the cubic Laves phase.
authors.affiliation: Laboratory of Crystallography, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Weber
authors.forename: Julia
authors.initials: J
authors.lastname: Dshemuchadse
authors.forename: Miroslav
authors.initials: M
authors.lastname: Kobas
authors.forename: Matthias
authors.initials: M
authors.lastname: Conrad
authors.forename: Bernd
authors.initials: B
authors.lastname: Harbrecht
authors.forename: Walter
authors.initials: W
authors.lastname: Steurer