Discussion of phasons in quasicrystals and their dynamics

Abstract

Phasons are a type of excitation peculiar to quasicrystals and other incommensurate phases arising as a consequence of their spatial quasiperiodicity. Phason-related excitations are also observed in complex crystal structures known as approximants. This article briefly reviews the concepts of phasons with focus on current issues in their regard. We examine both continuum (hydrodynamic) and discrete (tiling) descriptions of phasons and review the state of experimental validation of the basic theoretical notions.

Keywords:

• phason
• aperiodic materials
• approximants
• atomic dynamics
• defects in solids
• disorder
• quasicrystals

Acknowledgements

This article is motivated by a discussion on phasons in quasicrystals during the conference ‘Quasicrystals–The Silver Jubilee’. The discussion was led by the author who was assisted by a panel of experts consisting of Marc de Boissieu, Michael Feuerbacher, and Marek Mihalkovic, to whom the author is grateful. The current article presents the author's personal thoughts and views on the current state of affairs, and is not an attempt to provide an accurate record of the panel discussion.