Jumps in icosahedral quasicrystals |
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Authors: | J Roth |
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Institution: | Institut für Theoretische und Angewandte Physik, Universit?t Stuttgart, Pfaffenwaldring 57, 70550, Stuttgart, Germany
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Abstract: | Atomic jumps in icosahedral (AlCu)Li quasicrystals and related structures have been studied by molecular dynamics simulations.
In quasicrystalline structures jumps exists with jump vectors much shorter than an average nearest neighbor distance. This
is a consequence of the phasonic degree of freedom. The jumps therefore are called flips and the sites connected by the jump
vector are denoted alternative positions. We find that the atoms in the quasicrystal structures studied here do not flip to
alternative positions as proposed and observed in decagonal or dodecagonal quasicrystals but jump to sites which are at least
an ordinary interatomic distance apart. Furthermore we observe two diffusion regimes: below about 55% of the melting temperature
only small (AlCu) atoms carry out ring processes whereas at higher temperatures both kinds of atoms contribute to long-range
diffusion.
Received 21 July 1999 |
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Keywords: | PACS 61 44 Br Quasicrystals - 61 20 Ja Computer simulation of liquid structure |
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