Surface structural phase transitions on icosahedral Al–Pd–Mn

The sputtering of alloy surfaces with Ar+ ions may change their chemical composition by preferentially removing particular atomic species. For the icosahedral quasicrystal Al–Pd–Mn this produces reversible surface phase transitions either to a cubic structure or to a decagonal quasicrystal, depending on the temperature. In both the cases, the original icosahedral structure is restored upon annealing. We discuss the orientation of these phases relative to the underlying icosahedral bulk and the processes responsible for the restoration of the icosahedral structure.