Fason

En fason er en kvasipartikel, der eksisterer i kvasikrystaller grundet deres specifikke kvasiperiodiske gitterstruktur. Både fasoner og fononer er associeret med atomisk bevægelse, men hvor fononer er relateret til translation af atomer, er fasoner associeret med atomisk omorganisering. Som et resultat af disse omorganiseringer, bølger, der beskriver atomernes position i krystallet, ændrer fase, hvilket giver ophav til termen "fason".

Den hydrodynamiske teori af kvasikrystaller forudsiger at den konventionelle (fonon) deformering lempes hurtigt. I modsætning hertil, er fasonernes hendøning diffusiv og meget langsommere.^[1]

Kvasikrystaller som fremmer atomisk bevægelse i form af fasoner kan måske øge varmetransport i isolatorer dramatisk. ^[2]

Kilder/referencer[redigér | rediger kildetekst]

^ "Hydrodynamics of icosahedral quasicrystals" Phys. Rev. B 32, 7444–7452 (1985)
^ May 20, 2018, scitechdaily.com: Scientists Make First Observations of Phasons Arkiveret 21. maj 2018 hos Wayback Machine Citat: "...Researchers at the Department of Energy’s Oak Ridge National Laboratory made the first observations of waves of atomic rearrangements, known as phasons, propagating supersonically through a vibrating crystal lattice–a discovery that may dramatically improve heat transport in insulators and enable new strategies for heat management in future electronics devices...Fresnoite has a flexible framework structure that develops a competing order in the structure that does not match the underlying crystal order, like an overlay of mismatched tiles. Phasons are excitations associated with atomic rearrangements in the crystal that change the phase of waves describing the mismatch in the structure..."

Bøger[redigér | rediger kildetekst]

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 0-12-040601-2, Academic Press, 1988.
M.V. Jaric, ed, Introduction to the Mathematics of Quasicrystals (Aperiodicity and Order, Vol 2) ISBN 0-12-040602-0, 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.

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[1] "Hydrodynamics of icosahedral quasicrystals" Phys. Rev. B 32, 7444–7452 (1985)

[2] May 20, 2018, scitechdaily.com: Scientists Make First Observations of Phasons Arkiveret 21. maj 2018 hos Wayback Machine Citat: "...Researchers at the Department of Energy’s Oak Ridge National Laboratory made the first observations of waves of atomic rearrangements, known as phasons, propagating supersonically through a vibrating crystal lattice–a discovery that may dramatically improve heat transport in insulators and enable new strategies for heat management in future electronics devices...Fresnoite has a flexible framework structure that develops a competing order in the structure that does not match the underlying crystal order, like an overlay of mismatched tiles. Phasons are excitations associated with atomic rearrangements in the crystal that change the phase of waves describing the mismatch in the structure..."

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