Regensburg 2002 – wissenschaftliches Programm
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M: Metallphysik
M 11: Quasikristalle IV
M 11.3: Fachvortrag
Dienstag, 12. März 2002, 17:00–17:15, H6
Atomic-partial Vibrational Density of States in Quasicrystals — •R.A. Brand1, J. Voss1, A.-J. Dianoux2, B. Grushko3, Y. Calvayrac4, P.P. Parshin5, and M. Zemlyanov5 — 1Institute of Physics, University of Duisburg, Germany — 2ILL,Grenoble, France — 3IFF, Forschungszentrum Jülich, Jülich Germany — 4C.E.C.M./C.N.R.S., 15 rue G. Urbain, Vitry, France — 5Russian Research Centre “Kurchatov Institute” Moscow, Russia
We have studied the neutron-weighted vibrational density of states (VDOS) g(E) in several isotopic-substituted i-AlCuFe and d-AlNiFe quasicrystals using in the first, 65Cu or 57Fe and in the second, 60Ni or 57Fe to change the neutron cross sections in several different samples. From this data, the individual atomic-partial vibrational spectra g(E) for the three components have been separated in a new self-consistent calculation. The partial Debye-Waller factors are calculated by means of an iteration process with starting values of gi(E) (i = Al, Cu, Fe, or Al, Ni and Fe) as given from first-order approximations [1]. The partial contributions of 2- and 3-phonons scattering are simultaneously calculated, and these with the calculated background (due to frame-overlap) were subtracted from the raw data yielding the true one-phonon atomic-partial gi(E) for all three atomic components. In addition, atomic-partial properties such as the Debye-Waller factors, lattice stiffnesses and lattice specific heat contributions are calculated, showing the interest of this method for the study of structurally complex alloy phases.
[1] R.A. Brand et al., Phys. Rev. B 62 8849 (2000).