| Numéro |
J. Phys. Colloques
Volume 42, Numéro C6, Décembre 1981
International Conference on Phonon Physics
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|---|---|---|
| Page(s) | C6-371 - C6-373 | |
| DOI | https://doi.org/10.1051/jphyscol:19816107 | |
International Conference on Phonon Physics
J. Phys. Colloques 42 (1981) C6-371-C6-373
DOI: 10.1051/jphyscol:19816107
1 Kernforschungszentrum Karlsruhe, Institut für Angewandte Kernphysik I, D-7500 Karlsruhe, Postfach 3640, F.R.G.
2 Institute of Atomic Energy, Academia Sinica, Peking, China
3 Institut für Festkörperforschung, Kernforschungsanlage Jülich, D-5170 Jülich, F.R.G.
J. Phys. Colloques 42 (1981) C6-371-C6-373
DOI: 10.1051/jphyscol:19816107
LATTICE DYNAMICS OF YAl2 AND LaAl2 - A FURTHER CONTRIBUTION TO THE La-Y PUZZLE
C.T. Yeh1, 2, W. Reichardt1, B. Renker1, N. Nücker1 et M. Loewenhaupt31 Kernforschungszentrum Karlsruhe, Institut für Angewandte Kernphysik I, D-7500 Karlsruhe, Postfach 3640, F.R.G.
2 Institute of Atomic Energy, Academia Sinica, Peking, China
3 Institut für Festkörperforschung, Kernforschungsanlage Jülich, D-5170 Jülich, F.R.G.
Abstract
By means of inelastic neutron scattering we have measured the phonon dispersion curves in the main symmetry directions of the cubic Laves phases YAl2 and LaAl2. The phonon frequencies in LaAl2 are considerably softer than those of YAl2 which cannot be explained solely by the different atomic masses of La and Y. The experimental dispersion curves are well described by axially symmetric Born v. Kármán models taking into account interactions up t o the fifth nearest neighbors. From this analysis we find that the nearest neighbor Al-Al and TM-TM longitudinal force-constants of YAl2 are about twice those of LaAl2 whereas the TM-Al interactions are nearly equal.