Formation of a well ordered ultrathin aluminum oxide film on icosahedral AlPdMn quasicrystal

Abstract

We have exposed the pentagonal surface of icosahedral AlPdMn quasicrystal kept at $700\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ to several hundred langmuirs of ${\mathrm{O}}_{2}$, which results in the formation of a $5\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ thick, well ordered aluminum oxide film. The local structure of the film resembles that of the oxide layers formed on ordered binary alloys of Al except that the quasicrystalline substrate makes the film consist of five pairs of nanometer-size aluminum oxide domains exposing their nominal (111) faces parallel to the substrate surface and rotated by 72\ifmmode^\circ\else\textdegree\fi{} with respect to each other. The orientational relationship between these domains and the substrate is a consequence of the affinity of the icosahedral structure of AlPdMn to the CsCl structure.