Aperiodic Crystals and Beyond

Thursday, Jun 18th 2015

What is a crystal? And how do you define order or disorder in a structure? These are the questions addressed in Uwe Grimm's feature article Aperiodic Crystals and Beyond which was published in Acta Crystallographica B in June 2015, accompanied by a scientific commentary Structures beyond Superspace by Marjorie Senechal, Louise Wolff Kahn Professor Emerita in Mathematics and History of Science and Technology at Smith College. The discussion also featured in the news section of the website of the International Union of Crystallography (IUCr).

One interesting type of structure is the so-called pinwheel tiling; a realisation as a physical tiling covering the facades of the Federation Square buildings in Melbourne is depicted on  the journal issue's title page. While it is built from a single triangular shape, the tiles occur in infinitely many different orientations, leading to a discrete tiling with circular symmetry. The article argues that, while such structures have not yet been observed in nature, they are clearly ordered and should be considered to be within the realm of crystallography.

Professor Uwe Grimm is the Chair of the Commission on Aperiodic Crystals of the IUCr.

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