Dresden 2011 – wissenschaftliches Programm

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SKM-SYMF: SKM-Symposium Heterogenous Nucleation and Microstructure Formation: Steps towards a System- and Scale-bridging Understanding

SKM-SYMF 1: Heterogenous Nucleation and Microstructure Formation: Steps towards a System- and Scale-bridging Understanding

SKM-SYMF 1.1: Hauptvortrag

Donnerstag, 17. März 2011, 14:30–15:00, TRE Ma

Visualizing the structural solid-liquid transition with colloidal suspensions — •Peter Schall — University of Amsterdam, Amsterdam, The Netherlands

Crystal-liquid interfaces offer unique insight into the structural transition from solid to liquid, which is of key importance for understanding crystal nucleation and growth. These interfaces are, however, difficult to access experimentally because they are buried between two dense phases. We used a colloidal crystal-fluid equilibrium to obtain direct images of the structural solid-liquid transition: the individual particles in colloidal suspensions can be conveniently imaged and tracked in time using optical microscopy. We grow large colloidal crystals, and image their flat interfaces with the colloidal melt in three dimensions with confocal microscopy. We elucidate changes in the three-dimensional short range order across the interface, and determine the interfacial free energy directly from these configurational changes. Finally, we follow thermally excited fluctuations of the interface to measure the interfacial tension and its anisotropy, which are important parameters of crystal nucleation and growth.