Tuesday, January 17, 2012

Quasicrystals - The Concept of Dan Shechtman in Chemistry

The Nobel Prize 2011 Winning Concept - Quasicrystals

Original article by Dan Shechtman and others, Fascinating Quasicrystals, Interviews, Videos





Nobel Prize News


The original article of three pages can be viewed in

We conclude that icosahedral phase is a truly metastable phase which nucleates and grows for a range of cooling rates which are slow enough to prevent crystallization, either from the melt or from the icosahedral phase after its formation.

Related Papers

Steurer, Walter and Deloudi, Sofia, "Fascinating Quasicrystals", Acta Crystallographica,  2008, A64, 1-11

Mathematics related to quasicrystals
A periodic tiling

Definition of Crystal:
The IUCr Ad Interim Commission on Aperiodic Crystals published a working definition
(International Union of Crystallography, 1992): ‘‘by ‘crystal’ we mean any solid having an essentially discrete diffraction diagram, and by aperiodic crystal we mean any crystal in which three-dimensional lattice periodicity can be considered to be absent. As an extension, the latter term will also include those crystals in which three-dimensional periodicity is too weak to describe significant correlations in the
atomic configuration, but which can be properly described by crystallographic methods developed for actual aperiodic crystals.’’

Recently, the discussion on the crystal definition has been resumed because the term ‘essentially discrete diffraction diagram’ was found too vague for a definition (see Steurer, 2007a; Lifshitz, 2007; Ben
Abraham, 2007; Baake & Frettlo¨ h, 2007; Senechal, 2007; Janssen, 2007; Zimmermann, 2007).
(From: Steurer, Walter and Deloudi, Sofia, "Fascinating Quasicrystals", Acta Crystallographica,  2008, A64, 1-11,   https://files.me.com/sdeloudi/pltkvp  )

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