High pressure Mossbauer studies of stable quasicrystal Al_63.5Cu₂₄Fe_12.5

Abstract

The effect of high pressure on the short-range order in the stable Al_63.5Cu24Fe_12.5 quasicrystal has been studied using Mössbauer spectroscopy. In agreement with the earlier studies, the system shows no structural transition up to the highest pressure of 24.2 GPa used in the present study. Variations in both the isomer shift (IS) and the quadrupole splitting (QS) of two non-equivalent iron sites with pressure suggest changes in the short-range order in the system. A linear variation of IS with pressure can be understood in terms of the compressibility of the structure around the Fe atoms. An increase in the quadrupole splitting with pressure suggests that in addition to the compression, a distortion of the local arrangement of Al atoms around an Fe atom also takes place. At 24.2 GPa, the Mossbauer lines exhibit significant broadening, indicating an increase in the static disorder in the system with pressure.