8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.186Wed 711:10-14:00Heterogeneous nucleation and crystal growth in colloidsstudied by real space imagingFlorian Ziese, 1 Georg Maret, 1 and Urs Gasser 21 Universität Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany2 Laboratory for Neutron Scattering, Villigen, SwitzerlandHeterogeneous nucleation depends strongly on the size and surface properties of the seed particle[1]. We study crystal nucleation close to smooth curved surfaces realized with glass spheres(diameter 10 to 50 µm) as well as close to flat surfaces in suspensions of slightly charged,fluorescently dyed PMMA colloids with a diameter of 1. 9 µm. Positions and local structures of∼ 10 4 particles are determined in 3d by laser-scanning confocal microscopy. Crystal nuclei areidentified using local bond order parameters. We find that the number of crystal-like particles isclearly reduced near curved surfaces with radii smaller than 15 µm. For radii of curvature > ∼ 20µmthe number of crystal-like particles is comparable to that in the bulk. The crystal structure ofsubcritical nuclei is mainly oriented relative to the surface up to a distance about 8 µm. At largerdistances, their crystal structure is randomly oriented. Up to radii of curvature of 25 µm crystalnucleation is not accelerated by the seed particles.[1] A. Cacciuto, S. Auer and D. Frenkel, Nature 428, 404 (2004)186