Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 9: Quasikristalle III
M 9.2: Vortrag
Montag, 24. März 2003, 15:00–15:15, IFW B
Atomic Dynamics of Decagonal ZnMgY — •Jens-Boie Suck1, Max Scheffer1, and Roland Sterzel2 — 1Materials Research and Liquids, Institute of Physics, Technical University Chemnitz, D-09107 Chemnitz, Germany — 2Institute of Physics, J.W. Goethe University, Robert-Mayer-Str.2-4, D-60054 Frankfurt/M, Germany
Up to now only two stable alloy systems, AlPdMn and ZnMgRE/Y are known, in which icosahedral and decagonal quasicrystals (at different compositions) can be produced. After the atomic dynamics of icosahedral and decagonal AlPdMn have been investigated we have now performed a similar comparative study for icosahedral and decagonal ZnMgY. Decagonal Zn58Mg40Y2 was produced by melt spinning and subsequent annealing. X-ray diffraction and HRTEM investigations proved that 90% of the sample material is in the decagonal phase, while the remaining 10% is mainly crystalline Mg2Zn [1].
The experiments were performed at the thermal neutron time- of-flight spectrometer MARI at the spallation source ISIS (UK) using an incident energy of 75 meV, i.e. in a large region of energy and momentum transfers. Compared with the Generalized Vibrational Density Of States (GVDOS) of icosahedral ZnMgY we find a considerable difference not so much in the energy range of the subbands but in their absolute intensities. We attribute this difference rather to variations in the short range order of the atomic structure (and also due to their different compositions) than to the difference in their aperiodic long range order. [1] Sterzel, Dahlmann, Assmus, Saitho, Fuess, Mihalkovic, Suck, Phil.Mag.Lett.82 (2002) 235