Phason
Encyclopedia
Phason is a quasiparticle
existing in quasicrystal
s due to their specific, quasiperiodic lattice structure. Similar to phonon
, phason is associated with atomic motion. However, whereas phonons are related to translation of atoms, phasons are associated with atomic rearrangements. As a result of these rearrangements, waves, describing the position of atoms in crystal, change phase, thus the term "phason".
The hydrodynamic theory of the quasicrystals predicts that the conventional (phonon) strain relaxes rapidly. On the contrary, relaxation of the phason strain is diffusive and is much slower. Therefore, metastable quasicrystals grown by rapid quenching from the melt exhibit built-in phason strain associated with shifts and broadenings of X-ray and electron diffraction
peaks.
Quasiparticle
In physics, quasiparticles are emergent phenomena that occur when a microscopically complicated system such as a solid behaves as if it contained different weakly interacting particles in free space...
existing in quasicrystal
Quasicrystal
A quasiperiodic crystal, or, in short, quasicrystal, is a structure that is ordered but not periodic. A quasicrystalline pattern can continuously fill all available space, but it lacks translational symmetry...
s due to their specific, quasiperiodic lattice structure. Similar to phonon
Phonon
In physics, a phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, such as solids and some liquids...
, phason is associated with atomic motion. However, whereas phonons are related to translation of atoms, phasons are associated with atomic rearrangements. As a result of these rearrangements, waves, describing the position of atoms in crystal, change phase, thus the term "phason".
The hydrodynamic theory of the quasicrystals predicts that the conventional (phonon) strain relaxes rapidly. On the contrary, relaxation of the phason strain is diffusive and is much slower. Therefore, metastable quasicrystals grown by rapid quenching from the melt exhibit built-in phason strain associated with shifts and broadenings of X-ray and electron diffraction
Electron diffraction
Electron diffraction refers to the wave nature of electrons. However, from a technical or practical point of view, it may be regarded as a technique used to study matter by firing electrons at a sample and observing the resulting interference pattern...
peaks.
Books
- P.J. Steinhardt and S. Ostlund The Physics of Quasicrystals (Singapore: World Scientific, 1987)
- M.V. Jaric, ed, Introduction to Quasicrystals (Aperiodicity and Order, Vol 1) ISBN 012-04-0601-2, Academic Press, 1988.
- M.V. Jaric, ed, Introduction to the Mathematics of Quasicrystals (Aperiodicity and Order, Vol 2) ISBN 012-04-0602-0, Academic Press, 1989.
- D. P. DiVincenzo and P. J. Steinhardt, eds. Quasicrystals: The State of the Art. Directions in Condensed Matter Physics, Vol 11. ISBN 981-02-0522-8, 1991.
- M. Senechal, Quasicrystals and Geometry, Cambridge University Press, 1995.
- J. Patera, Quasicrystals and Discrete Geometry , 1998.
- E. Belin-Ferre et al., eds. Quasicrystals, 2000.
- Hans-Rainer Trebin ed., Quasicrystals: Structure and Physical Properties 2003.