Stabilization of the pentagonal surface of the icosahedral AlPdMn quasicrystal by controlled Si absorption

The Debye-temperature of the pentagonal surface of the icosahedral AlPdMn quasicrystal (QC) is measured by means of low-energy electron diffraction after the absorption of different amounts of Si. We observe an increase of the surface Debye-temperature from 300±7 K for the freshly prepared surface to 330±7 K after the absorption of 60-Å Si. Because the quasicrystalline order persists at the surface in spite of the diffusion of Si into the substrate, we suggest that the diffusion is dominated by a vacancy-mediated process.