Dynamics of the ZnMgY icosahedral phase

K. Shibata, R. Currat, M. De Boissieu, T. J. Sato, H. Takakura, A. P. Tsai

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Abstract

The dynamics of the icosahedral ZnMgY phase has been investigated on a single-grain quasicrystalline sample using inelastic neutron scattering. Similarly to other quasicrystals we observe well defined acoustic modes for values of the wavevector smaller than 0.3 Å-1. We find a longitudinal sound velocity equal to 4800 m s-1 and an isotropic transverse sound velocity equal to 3100 m s-1. The acoustic character and the broadening of transverse excitations has been studied extensively. We find that transverse excitations remain acoustic up to q = 0.5 Å-1. For q lying between 0.3 and 0.5 Å-1 we observe a broadening, which is independent of the propagation or polarization direction, while the dispersion relation departs from linearity. For q = 0.6 Å-1 there is a resonance with an optic-like excitation located at about 10 meV and the signal can no longer be described by a single acoustic mode. For larger wavevectors we observe a broad distribution of modes, which can be split into three dispersionless optical bands located at 8, 12 and 17 meV. The 8 and 12 meV bands are associated with the crossing of pseudo-zone boundaries by the acoustic branch. A detailed comparison with results obtained in the i-AlPdMn phase shows significant differences: in particular the broadening of transverse acoustic modes is much less pronounced in the ZnMgY phase than in the i-AlPdMn one.

Original languageEnglish
Pages (from-to)1847-1863
Number of pages17
JournalJournal of Physics Condensed Matter
Volume14
Issue number8
DOIs
Publication statusPublished - 2002 Mar 4
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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    Shibata, K., Currat, R., De Boissieu, M., Sato, T. J., Takakura, H., & Tsai, A. P. (2002). Dynamics of the ZnMgY icosahedral phase. Journal of Physics Condensed Matter, 14(8), 1847-1863. https://doi.org/10.1088/0953-8984/14/8/313