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Aperiodic '94

... and Dining. D. Pandey, W. Steurer, A. Temienov, and G. Chapuis commence eating (periodically) in Les Diablerets. (Photo courtesy of G. Chapuis)

Aperiodic '94, an International Conference on Modulated Structures, Polytypes and Quasicrystals, was held in Les Diablerets (Switzerland), an alpine resort dominated by a glacier. The conference promoted the development of methods and nomenclature for the crystallographic investigation of aperiodic crystals.

The field of quasicrystal structures was addressed by C. Janot, Grenoble and W. Steurer, Zurich (icosahedral and decagonal phases respectively); K Kelton, St Louis (titanium based quasicrystals); J.-M. Dubois, Nancy (physical properties and potential applications); and K. Hiraga, Sendai (high-resolution electron microscopy of decagonal quasi crystals). Models were presented describing incommensurate structures in silicate minerals and feldspars (V. Heine, Cambridge, UK), bismuth high Tc superconductors (M. Walker. Toronto), organic compounds (V. B. Gaillard, Lausanne), and phase transition mechanisms (K. Parlinski, Krakov).

The optical properties of incommensurate structures were described by J. Etxebarria (Bilbao) and O. Vlokh (Lviv). S. Van Smaalen (Groningen) and A. Yamamoto (Tsukuba) revealed how the concept of superspace group can be used to describe intergrowth compounds and composite crystal structures. D. Pandey (Varanasi), A. Baronnet (Marseille) and J. Grell (Berlin) presented the current state of research in the field of polytypes, polytypism and OD layer structures. J.-M. Kiat (Saclay) presented a survey of the intricate field of premartensitic anomalies in diffraction-diffusion experiments.

Mathematicians had an opportunity to forecast future trends. L. Danzer (Dortmund) described an interesting three dimensional prototile that can fill space without translation. P. Kramer (Tübingen) introduced non-commutative crystallography with applications in quasi periodic tilings, A. Janner (Nijmegen) and R. Galiulin (Moscow) revealed some interesting aspects of non-Euclidean symmetry hidden in crystal structures, and A. Mackay (London) presented additional ideas in 'non-conformist crystallography'.

The social program included a concert with alpenhorn, visits to a museum and a Roman ruins and a dinner featuring "raclette", a local speciality based on mountain cheese.

Sponsors were the University of Lausanne, the IUCr and the Soros Foundation. A complete report is available at URL http://www.unige.ch/crystal/aperiodic/mtgch94-index.html. The proceedings of the meeting will be published by World Scientific.

Gervais Chapuis
Chair, Commission on Aperiodic Crystals