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The \gamma-brass structure and the Boerdijk–Coxeter helix

Lord, EA and Ranganathan, S (2004) The \gamma-brass structure and the Boerdijk–Coxeter helix. In: Journal of Non-Crystalline Solids, 334-33 . pp. 121-125.

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The \gamma-brass structure was for a long time regarded as a modified bcc structure. It is more accurately described in terms of a 26-atom cluster consisting of four interpenetrating icosahedral clusters. An alternative description in terms of a 38-atom cluster is also illuminating. We discuss the \gamma-brass structure in terms of the packing of spheres and the packing of 'almost regular’ tetrahedra and demonstrate a close relationship to the helical sphere packings investigated by Boerdijk, who considered the configuration of touching spheres centred at the vertices of a Coxeter helix, and extended it by adding an extra layer of spheres. Adding a further layer of spheres gives a rod-like structure in which every sphere of the original helix is surrounded by twelve others, configured as a somewhat distorted icosahedron. Thus each tetrahedron of the initial structure is then shared by four icosahedra. This 26-sphere cluster is a slightly distorted form of the 26-atom \gamma-brass cluster.

Item Type: Journal Article
Publication: Journal of Non-Crystalline Solids
Publisher: Elsevier
Additional Information: Copyright of this article belongs to Elsevier.
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 30 Nov 2007
Last Modified: 19 Sep 2010 04:36
URI: http://eprints.iisc.ac.in/id/eprint/10134

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