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O: Fachverband Oberflächenphysik

O 69: Metal Substrates: Clean Surfaces

O 69.2: Vortrag

Freitag, 30. März 2007, 10:30–10:45, H41

Influence of defects in the NiAl(100) surface on structure and energy — •Kerrin Dössel, Daniel Lerch, Stefan Müller, and Klaus Heinz — Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr.7, D-91058 Erlangen

The ordered B2-phase of NiAl is stable over a wide composition range around the 1:1 stoichiometry. Therefore, atomic defects such as vacancies or antisites must exist, whose concentration - especially at grain boundaries and surfaces - may heavily influence the stability of the alloy with respect to segregation phenomena. We studied the atomic structure and energetics of the NiAl(100) surface in view of the existence of vacancies and antisites by first-principles calculations and quantitative Low-Energy Electron Diffraction (LEED). The influence of defects on the surface formation and structure and their correlation to segregation will be discussed by use of DFT-based results. The enthalpy of surface formation and the surface structure have been calculated using Density Functional Theory for the ideal surface as well as for different defect types and configurations. The results will be compared to the best-fit structure resulting from our LEED structure analysis.