PHONON DISPERSION RELATION OF MASS
DEFECT CONCENTRATED ALLOY Ni-Pt AND ITS
INTERPRETATION BY CPA
N. Kunitomi, Y. Tsunoda, Y. Hirai
To cite this version:
N. Kunitomi, Y. Tsunoda, Y. Hirai. PHONON DISPERSION RELATION OF MASS DEFECT CONCENTRATED ALLOY Ni-Pt AND ITS INTERPRETATION BY CPA. Journal
de Physique Colloques, 1974, 35 (C4), pp.C4-251-C4-251. <10.1051/jphyscol:1974446>. <jpa00215637>
HAL Id: jpa-00215637
https://hal.archives-ouvertes.fr/jpa-00215637
Submitted on 1 Jan 1974
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JOURNAL DE PHYSIQUE
Colloque C4, supplkment au no 5, tome 35, Mai 1974, page C4-251
PHONON DISPERSION RELATION OF MASS DEFECT CONCENTRATED
ALLOY Ni-Pt AND ITS INTERPRETATION BY CPA
N. KUNITOMI, Y. TSUNODA and Y. HIRAI
~ e p a r t m e n of
t Physics, Faculty of Science, Osaka University,
Toyonaka, Osaka, 560, Japan
R&sum&.- Relation de Dispersion pour les Phonons dans les Alliages concentres Ni-Pt avec
defaut de masse. Les vibrations atomiques dans des cristaux simples de l'alliage Ni-Pt ont kt&
etudiks au moyen de la diffusion inelastique de neutrons. Des mesures ont BtB effectukes pour les
branches [OOC] T. Les resultats sont compares avec des calculs bases sur la CPA.
Abstract. - By means of inelastic scattering of neutrons, the phonon dispersion relations of
00C T branch have been measured for Ni-Pt alloys with various concentrations. For Nig5Pt5and
Ni70Pt30, double peaks were found in the neutron scattering spectra obtained by constant q
method at about q = 0.5. The dispersion relation has an energy gap corresponding to the appearance of the double peaks. The gap with is about 3 meV and 6 meV for Nig5Pt5 and Ni70Ni30,
respectively. Taylor has calculated the spectral Green function of phonons in mass defect concentrated alloy AuCu under CPA. From the positions and widths of the peaks of the Green function,
one can construct the dispersion curves of phonon mode as well as width. The theoretical dispersion
relation, thus obtained has an energy gap corresponding to the localized vibrations. The similarity
of the theoretical and experimental dispersion relations indicates that the nature of phonons in
highly concentrated mass defect alloys can be well interpreted by the theory under CPA. The reason
of the appearance of the double phonons corresponding to a single wave number can be understood
by considering that the vibration frequency of an atom changes in time or in space from higher one
which is a localized mode around light atoms to lower one which is a localized mode around heavy
atoms.
The full paper of this work has been published in Solid State Commun. 13 (1973) 495.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1974446