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MM: Fachverband Metall- und Materialphysik

MM 60: Phase Transitions II

MM 60.3: Vortrag

Donnerstag, 25. März 2010, 16:00–16:15, H5

Competition between heterogeneous and homogeneous nucleation near a flat wall — Andreas Engelbrecht, Roushdey Salh, and •Hans Joachim Schöpe — Johannes Gutenberg-University, 55099 Mainz, Germany

The physical and chemical properties of solidified crystalline materials depend in a crucial way from the conditions of crystal nucleation. In order to improve the conditions of production processes and even to develop novel materials with extraordinary properties a detailed knowledge of the nucleation process is most desired.

We studied the competition between heterogeneous and homogeneous nucleation in colloidal model systems of charged spheres close to the container walls as function of metastability.

Our results show some unexpected behaviour: Although the appearing polycrystal displays a high amount of wall crystal we find that the heterogeneous nucleation at the container walls is delayed in comparison to the homogeneous bulk nucleation and its rate density appears surprisingly slightly smaller demonstrating the complexity of the observed crystallization process.