Lord, EA and Ranganathan, S (2004) The γ-brass structure and the Boerdijk–Coxeter helix. In: 8th International Conference on Quasicrystals, SEP 08-13, 2002, Bangalore, INDIA.
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Abstract
The γ-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 γ-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 γ-brass cluster.
Item Type: | Conference Paper |
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Publisher: | Elsevier Science |
Additional Information: | Copyright of this article belongs to Elsevier Science. |
Keywords: | C200;M280;S440 |
Department/Centre: | Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy) |
Date Deposited: | 08 Mar 2012 09:25 |
Last Modified: | 08 Mar 2012 09:25 |
URI: | http://eprints.iisc.ac.in/id/eprint/43810 |
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