Berlin 2005 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 14: Complex Fluids
DY 14.11: Vortrag
Freitag, 4. März 2005, 18:00–18:15, TU H3010
The influence of particle size distribution on the solidification kinetics in colloidal hard sphere systems — •Hans Joachim Schöpe1, Gary Bryant2, and William van Megen2 — 1Johannes Gutenberg-Universität Mainz, Institut für Physik, KOMET 336, Staudinger Weg 7, D 55099 Mainz, Deutschland — 2Department of Applied Physics, Royal Melbourne Institute of Technology, GPO Box 2476V, Melbourne 3001, Australia
A complete understanding of the solidification process (nucleation, crystal growth, ripening, vitrification) is one of the long-standing problems in solid-state physics. The use of colloidal model systems provides an ideal experimental system to reduce this lack of knowledge. A significant difference between the particles in a suspension and the atoms of a melt is that colloidal particles always have a particle size distribution (PSD). One of the least well characterized parameters in the solidification process in colloidal systems is the effect of the PSD. Here we present systematic measurements of the solidification kinetics and of the phase behaviour in dependence of the PSD of a one component system. This investigation shows that polydisperity has a significant influence to nucleation, growth velocity and the morphology and crystal structure of the resulting sample. These studies also indicate that in addition to the rate of crystallization, the crystal structure and the propensity to vitrify are also very sensitive to small variations in the particle size distribution. Surprisingly we observe a two step behaviour in the nucleation rate, which is independent of the PSD