Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 28: Pattern formation in colloidal and granular systems II

DY 28.4: Vortrag

Freitag, 27. März 2009, 11:00–11:15, HÜL 386

Random-Close Packing in Binary Mixtures in Two Dimensions — •Elmar Staerk¹, Stefan Luding², and Matthias Sperl¹ — ¹Institut fuer Materialphysik im Weltraum, DLR, Koeln — ²Universiteit Twente, The Netherlands

Binary mixtures are investigated at the transition from loose to load-bearing packings. The transition is determined both in computer simulation and experimentally in assemblies of stress-birefringent particles. Both the size ratio of smaller to bigger particles as well as the concentration of smaller particles is varied systematically. The transition is determined accurately by observing a discontinuity in the number of contacts per particle. It is found that the variation of the transition density follows qualitatively recent predictions for the glass transitions in binary mixtures of colloidal particles. At the transition point – especially for asymmetric mixtures – we find non-trivial variations of contact numbers, apparent exponents, and the number of rattlers.