Compression behaviour and pressure-induced strain of icosahedral Zn-Mg-Y quasicrystal

Abstract

The compression behaviour and pressure-induced disorder of an icosahedral Zn55Mg35Y10 quasicrystal has been investigated by means of an in-situ angle-dispersive X-ray powder diffraction method using synchrotron radiations. The icosahedral structure was found to be essentially stable under high pressures up to 70 GPa and at 1 bar after recovered from 70 GPa. However, it should be noted that all peaks of the X-ray diffraction after recovered were broad even at 1bar. This indicates that the recovered sample contains a lot of pressure-induced strains even though it was an icosahedral quasicrystal. It was found that there was a linear relation between Q// (physical momentum) and HWHM (Half Width at Half Maximum) of the X-ray diffraction peaks of the sample recovered from 70 GPa. On the other hand, there was no correlation between Q⊥ (phason momentum) and HWHM. In addition, there was no linear relation between (Q⊥/Q//)2 and (HWHM/Q//)2. These analyses indicate that the pressure-induced strains in the extremely strained Zn-Mg-Y quasicrystal recovered from 70 GPa are explained by neither of the icosahedral glass nor the frozen-in phason strain models, and explained well by the simple lattice (phonon) strain.