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Fifty years of aperiodic crystals

Acta Cryst. (2012). A68, 667-674 (

[Patterson pattern] Patterson pattern for a Fibonacci chain: the chain appears along a horizontal line, the 'physical space'.

After von Laue had shown, in 1912, that crystals diffract X-rays and have ordered arrays of atoms, it was assumed that an essential property of crystals was their lattice periodicity. In 1982 quasicrystals were discovered showing crystals with fivefold symmetry axes, which exclude lattice periodicity. This was, however, not the first case of a crystal without lattice periodicity. In the beginning of the 1960s more and more examples were found, such that in 1982 quite a number of crystallographers were aware of their existence. A brief history of the slowly growing idea that crystals are not necessarily lattice periodic, culminating in the discovery of quasicrystals, is given.

T. Janssen