Berlin 2015 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 13: Microstructure and Phase Transformations III

MM 13.4: Talk

Monday, March 16, 2015, 16:30–16:45, H 0106

Thermodynamics of point defects and diffusion mechanisms in B2-ordered compounds — •Michael Leitner — Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany

A scheme to classify the point defect thermodynamics in B2 compounds by way of two non-trivial energy parameters is presented, which is rigorously valid for small defect concentrations in both stoichiometry and off-stoichiometry. It is applied to published ab initio defect formation energies, and the variety of resulting phenomena is demonstrated. Further, by introducing model assumptions the consequences for the active diffusion mechanisms are deduced. It is shown that particularly for the case of off-stoichiometry, the assumed prevalence of either the six-jump cycle or the triple defect mechanism has to be reconsidered, as two qualitatively different mechanisms emerge as likely candidates for the dominant effect.