Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 46: Liquid and Amorphous Metals

MM 46.6: Vortrag

Mittwoch, 14. März 2018, 18:15–18:30, TC 010

The Stokes-Einstein relation of a simple liquid metal and its relationship to changes in the microscopic dynamics with increasing temperature: the experimental viewpoint — •Franz Demmel — ISIS Facility, Didcot, UK

For liquid rubidium the Stokes-Einstein-relation is well fulfilled near the melting point with an effective hydrodynamic diameter, which agrees with a value from structural investigations. A wealth of thermodynamic and microscopic data exist for a wide range of temperatures for liquid rubidium and hence it represents a good test bed. With increasing temperature the SE-relation shows a departure from the expected temperature behaviour. That temperature range coincides with an observed change in the microscopic relaxation dynamics on nearest neighbor distances [1]. The derived average relaxation time for density fluctuations on this microscopic length scale shows a non-Arrhenius behaviour. Combining the experimental macroscopic self-diffusion coefficient with the average relaxation time, a violation of the SE-relation at the same temperature range can be demonstrated. Simulations and experimental results from other metals and alloys demonstrate a similar behavior and point to a possible universal change in the dynamics of liquid metals [2]. [1] F. Demmel et al, Phys. Rev. B 73, 104207 (2006) [2] F. Demmel et al, J.Phys.: Condens. Matter 27 455102 (2015); A. Jaiswal et al, Phys. Rev. Lett. 91 205701 (2016); X.J. Han and H.R. Schober, Phys Rev B 83 224201 (2011)