Regensburg 2002 – scientific programme

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M: Metallphysik

M 11: Quasikristalle IV

M 11.3: Fachvortrag

Tuesday, March 12, 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 g_i(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 g_i(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).