Phason

Phason is a quasiparticle existing in quasicrystals 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".

In the superspace picture, aperiodic crystals are obtained from the section of a periodic crystal of higher dimension (up to 6D) cut at an irrational angle. While phonons change the position atoms relative to the crystal structure in space, phasons change the position of atoms relative to the quasi-crystal structure and the cut through superspace that defines it. Phonon modes are therefore excitations of the "in plane" real (also called parallel or external) space whereas phasons are excitations of the perpendicular (also called internal) space.[1]

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.[2] Therefore, metastable quasicrystals grown by rapid quenching from the melt exhibit built-in phason strain[3] associated with shifts and anisotropic broadenings of X-ray and electron diffraction peaks.[4][5]

References
  1. de Boissieu M (March 2019). "Ted Janssen and aperiodic crystals". Acta Crystallographica Section A. 75 (Pt 2): 273–280. doi:10.1107/S2053273318016765. PMC 6396404. PMID 30821260.
  2. Lubensky TC, Ramaswamy S, Toner J (December 1985). "Hydrodynamics of icosahedral quasicrystals". Physical Review B. 32 (11): 7444–7452. Bibcode:1985PhRvB..32.7444L. doi:10.1103/physrevb.32.7444. PMID 9936890.
  3. Tsai AP (April 2008). "Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy". Science and Technology of Advanced Materials. 9 (1): 013008. doi:10.1088/1468-6996/9/1/013008. PMC 5099795. PMID 27877926.
  4. Lubensky TC, Socolar JE, Steinhardt PJ, Bancel PA, Heiney AP (September 1986). "Distortion and peak broadening in quasicrystal diffraction patterns". Physical Review Letters. 57 (12): 1440–1443. Bibcode:1986PhRvL..57.1440L. doi:10.1103/PhysRevLett.57.1440. PMID 10033450.
  5. Yamada T, Takakura H, Euchner H, Pay Gómez C, Bosak A, Fertey P, de Boissieu M (July 2016). "Atomic structure and phason modes of the Sc-Zn icosahedral quasicrystal". IUCrJ. 3 (Pt 4): 247–58. doi:10.1107/S2052252516007041. PMC 4937780. PMID 27437112.

Books
  • Steinhardt PJ, Ostlund S (1987). The Physics of Quasicrystals. Singapore: World Scientific. ISBN 978-9971-5-0226-3.
  • Jaric MV, ed. (1988). Introduction to Quasicrystals. Aperiodicity and Order. 1. Academic Press. ISBN 978-0-12-040601-2.
  • Jaric MV, ed. (1989). Introduction to the Mathematics of Quasicrystals. Aperiodicity and Order. 2. Academic Press. ISBN 978-0-12-040601-2.
  • DiVincenzo DP, Steinhardt PJ, eds. (1991). Quasicrystals: The State of the Art. Directions in Condensed Matter Physics. 11. Singapore: World Scientific. ISBN 978-981-02-0522-5.
  • Senechal M (1995). Quasicrystals and Geometry. Cambridge University Press. ISBN 978-0-521-57541-6.
  • Patera J (1998). Quasicrystals and Discrete Geometry. American Mathematical Society. ISBN 978-0-8218-0682-1.
  • Belin-Ferre E, Berger C, Quiquandon M, Sadoc A, eds. (2000). Quasicrystals. World Scientific Publishing Company. ISBN 978-981-02-4281-7.
  • Trebin HR, ed. (2003). Quasicrystals: Structure and Physical Properties. Wiley-VCH. ISBN 978-3-527-40399-8.
  • Janssen T, Chapuis G, Boissieu (2018). Aperiodic structures: from modulated structures to quasicrystals. Oxford Science Publications. ISBN 978-0-19-882444-2.

See also


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