Experimental evaluation of phonon–phason coupling in icosahedral quasicrystals

Abstract

By measuring phonon strain introduced in crystal approximants, the sign and magnitude of the phonon–phason coupling constant have been evaluated for icosahedral quasicrystals of Mg–Ga–Al–Zn and Al–Cu–Fe systems. The evaluated coupling constants are approximately −0.04μ and 0.004μ (μ = shear modulus) for the former and the latter, respectively. They are in good agreement with the results of a previously reported theoretical calculation. Possible effects of phonon–phason coupling on the onset of phasonic elastic instability in icosahedral quasicrystals are discussed.

Acknowledgements

This work was financially supported by Core Research in Environmental Science and Technology (CREST), Japan Science and Technology Corporation.