Phonon-phason coupling in icosahedral quasicrystals
Department of Physics, Cornell University - Ithaca NY 14853-2501, USA
Accepted: 15 April 1999
From relaxation simulations of decoration-based quasicrystal structure models using microscopically based interatomic pair potentials, we have calculated the (usually neglected) phonon-phason coupling constant. Its sign is opposite for the two alloys studied, i-AlMn and i-(Al,Cu)Li; a dimensionless measure of its magnitude relative to the phonon and phason elastic constants is of order 1/10, suggesting its effects are small but detectable. We also give a criterion for when phonon-phason effects are noticeable in diffuse tails of Bragg peaks.
PACS: 61.44.Br – Quasicrystals / 62.20.Dc – Elasticity, elastic constants / 61.10.Dp – Theories of X-ray diffraction and scattering (including small-angle scattering)
© EDP Sciences, 1999