Modelling of the energetics and kinetics of Al deposition on 5-fold Al-rich quasicrystal surfaces

• Published in: Philosophical magazine (Abingdon, England) Vol. 86; no. 6-8; pp. 831 - 840
• Main Authors: Ghosh, C., Liu, D.-J., Jenks, C. J., Thiel, P. A., Evans, J. W.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Abingdon Taylor & Francis Group 21.02.2006; Taylor and Francis
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Pair potentials; Adsorption site; Aluminium; Quasicrystals; Deposition process; Surface structure; Surface termination; Aluminium alloys; Adsorbed state; Adsorption structure; Potential energy surfaces; Adatoms; Modelling; Kinetics; Lennard Jones model
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430500334750

We determine potential energy surfaces for the binding of Al adatoms on 5-fold AlPdMn and AlCuFe quasicrystal surfaces. Appropriate geometric models are used to select physical surface terminations. The interaction between the Al adsorbate and the substrate is described using Lennard-Jones pair-wise interactions, with parameters chosen to fit ab initio energetics for Al on relevant single crystal substrates. We identify a 'disordered-bond-network' (DBN) of local adsorption sites, which includes deep 'starfish' and 'incomplete starfish' ensembles. Our primary interest is in the kinetics of deposition and aggregation of Al atoms, and the possible formation of pseudomorphic starfish islands at starfish ensembles (observed for Al deposition on AlCuFe). The deposition process is modeled within the framework of a DBN lattice-gas model, wherein we specify rates for deposition and for hopping between neighboring sites of the DBN, as well as Al-Al adsorbate interactions, which stabilize islands. We, thus, present a picture for the formation of starfish islands subject to the competition between various deep sites for Al adatoms.