Minimal model of the phonon-phason dynamics in icosahedral quasicrystals and its application to the problem of internal friction in the i-AlPdMn alloy - art. no. 144204

摘要

Different existing elastodynamical models of icosahedral quasicrystals are analyzed. The simplest minimal model of the phonon-phason dynamics is formulated. Physical restrictions and possible applications of the proposed model are considered. Several generalizations of the minimal model are discussed. It is shown that the phonon-phason coupling induces a resonant absorption peak of low-frequency sound waves in the temperature region corresponding to a thermal activation of phason excitations. The maximum value of the logarithmic decrement of the sound wave damping depends on the propagation direction and the wave polarization. The anisotropy is proportional to the square of the phonon-phason coupling constant K-3. Our estimation shows that the effect can be resolved experimentally if the relative value of K-3 is not negligible with respect to four other elastic constants of the icosahedral quasicrystal. Namely, the difference should not exceed two orders of magnitude. [References: 30]