Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster: Crystallisation, Nucleation and Self assembly

CPP 17.9: Poster

Dienstag, 27. März 2012, 18:15–20:15, Poster A

Heterogeneous and homogeneous crystal nucleation in colloidal hard-sphere like microgels at low metastabilities — •Markus Franke and Hans Joachim Schöpe — Johannes Gutenberg Universität Mainz, Institut für Physik, Staudinger Weg 7, 55099 Mainz, Germany

Crystal nucleation is dominated by heterogeneous nucleation in most cases, especially at low undercoolings (metastabilities, chemical potential differences) and for that reason heterogeneous nucleation on container walls or impurities is almost unavoidable. The hard sphere model system is the simplest model system showing a fluid crystal phase transition. Sterically stabilized colloidal particles in a refractive and density matching solvent provides such a hard sphere system for experimentalists. We studied the crystallization kinetics of homogeneous bulk as well as the heterogeneous wall crystallization within the fluid crystal coexistence region. Parameters characterizing the crystallization process (induction times, growth coefficients, nucleation rate densities,...) were determined by using time resolved static light scattering and Bragg microscopy. By performing further analysis according to classical nucleation theory we can show that wall crystallization is induced by complete wetting of the cell walls with crystalline layers leading to a vanishing nucleation barrier.