Münster 1999 – scientific programme

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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.