Evidence for surface compaction in Al-incorporated Al-Pd-Mn quasicrystals

The quasicrystalline order at the pentagonal surface of the icosahedral Al-Pd-Mn is monitored by low-energy electron diffraction during the vacuum deposition of aluminum. We find that thick Al layers can readily be diffused into the bulk if the substrate is kept at 770 K, with no measurable changes in the surface quasicrystalline order. In the process, the surface Debye temperature (298 K) increases by more than 100 K suggesting the filling of the vacancy-rich, open-structured pentagonal surface of the Al-Pd-Mn quasicrystal with Al.