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M: Metallphysik
M 3: Quasikristalle I
M 3.8: Talk
Monday, March 22, 1999, 12:30–12:45, S 9
Temperature dependence of Phonon DOS in decagonal Al70Co15Ni15 — •Hamid Elhor, Marek Mihalkovic, and Jens-Boie Suck — Materialforschung und Flüssigkeiten, Institut für Physik,
TU Chemnitz, D-09107 Chemnitz.
We performed detailed analysis of the recently measured temperature dependence
of the generalised vibrational density of states in decagonal quasicrystal
Al70Co15Ni15.
Using a periodic approximant as an atomic structure
model for the quasicrystal and a spring-constant model which we fitted in
harmonic approximation to the room temperature GVDOS, we obtained the partial Aluminiu
m and transition metal phonon DOS. Using these partials we were able
to recover the Al70Co15Ni15 phonon DOS from the experimental GVDOS,
and by means of an iterative Monte Carlo simulation we reconstructed the
temperature dependence of the frequency-shift patterns related to the
expansion of the sample.
As a result we calculated quantities like the sound velocity, the Grüneisen
parameter, the Debye-Waller factor and the phonon contribution to the heat
capacity and entropy. Some of these quantities can be compared directly with other independent experiments.