The surface structure of a β-Al(Cu1−xFex)-(110) film formed on an AlCuFe quasicrystal substrate, analyzed by dynamical LEED

• Published in: Surface science 1998-08, Vol.411 (1-2), p.86-98
• Main Authors: Shi, F, Shen, Z, Delaney, D.W, Goldman, A.I, Jenks, C.J, Kramer, M.J, Lograsso, T, Thiel, P.A, Van Hove, M.A
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Low energy electron diffraction (LEED); Metallic surfaces; Metals. Metallurgy; Physics; Quasicrystals; Semi-periodic solids; Solid surfaces and solid-solid interfaces; Structure of solids and liquids; crystallography; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(98)00334-3

In order to understand the unique properties of quasicrystalline surfaces, it is paramount to compare quasicrystalline and crystalline surfaces of similar chemical composition. To that end, the fivefold surface of an AlCuFe quasicrystal substrate was transformed, by ion bombardment and annealing, into a film with the β-Al(Cu1−xFex) bulk structure. This is a CsCl structure with Fe and Cu atoms randomly occupying the body-center sites, and Al atoms at the corner sites. The film exposes a (110) free surface: its external structure was analyzed by dynamical low-energy electron diffraction in terms of atomic positions and layer-wise composition. The best fit between theory and experiment slightly favors a copper-rich composition in the surface layers (x=0), although the sensitivity to the value of x is low, because Cu and Fe are very similar electron scatterers. The Al atoms in the surface layer buckle outward by 0.12±0.04Å relative to the Cu or Fe atoms in the same layer, while other relaxations from the bulk structure are small.