Dresden 2011 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 31: Postersitzung II

MM 31.1: Poster

Wednesday, March 16, 2011, 17:15–18:45, P5

Structure-optimization of the Ξ-phases in the Al-Pd-Mn system — •Benjamin Frigan¹, Marek Mihalkovič², and Hans-Rainer Trebin¹ — ¹Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Germany — ²Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia

The Ξ-phases – with ξ and ξ′ being the simplest ones – are probably the most investigated ternary phases. The experimental structure refinement of ξ′ carried out by Boudard et al. dates back more than 10 years. Almost all present studies rely on this structure proposal. Here we present an optimization of the Boudard model using a combination of classical molecular dynamics and density functional theory. We determine an optimal configuration for the Al atoms on the innermost shell of the pseudo-Mackay clusters (PMC). These Al atoms could not be resolved very accurately in experiment. Furthermore, we examine the "glue" atoms, i.e. those not belonging to any PMC. In order to get an estimate for the stability of a phase the ground state energies are calculated relative to other binary and ternary compounds coexisting in the Al-Pd-Mn system. The results are applied to the ξ₁′-phase (ε₁₆) where the projections of the PMC columns form pentagons and nonagons.