Regensburg 2004 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.66: Poster

Donnerstag, 11. März 2004, 16:00–18:00, Poster D

Heterogeneous Nucleation of charged sphere suspensions on shear induced precursors — •Thomas Palberg, Andreas Stipp, Ralf Biehl, Hans Joachim Schöpe, Jianing Liu, and Thorsten Preis — Institut f. Physik, Universität Mainz, Staudinger Weg 7, 55128 Mainz

Growth of oriented single crystals may be obtained from shear melts of colloidal particles after nucleation at the container walls. Using different microscopic and scattering techniques we here studied precursors of such nuclei induced by steady shear. In all cases we observed shear layer structures which were oriented with their densest plane parallel to the container wall and their densest packed direction parallel to the flow. A strong correlation between the modes of motion and the type of interlayer registering is observed. Depending on the shear geometry used, the equilibrium phase, the strength and the range of interaction such layer structures either disappear upon increase of the shear rate or grow to macroscopic objects. Stop of shear may lead to an interesting competition between the decay of these usually meta-stable structures in favour of the shear melt and their stabilisation through coverage by an epitaxially growing wall crystal. In the latter case the shear layer residues act as pre-structured substrate.