Europhys. Lett.
Volume 68, Number 1, October 2004
Page(s) 120 - 126
Section Interdisciplinary physics and related areas of science and technology
Published online 01 September 2004
Europhys. Lett., 68 (1), pp. 120-126 (2004)
DOI: 10.1209/epl/i2004-10168-7

Colloidal Brazil-nut effect in sediments of binary charged suspensions

A. Esztermann and H. Löwen

Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1, D-40225 Düsseldorf, Germany

received 13 April 2004; accepted in final form 30 July 2004

Equilibrium sedimentation density profiles of charged binary colloidal suspensions are calculated by computer simulations and density-functional theory. For deionized samples, we predict a colloidal "Brazil nut" effect: heavy colloidal particles sediment on top of the lighter ones provided that their mass per charge is smaller than that of the lighter ones. This effect is verifiable in settling experiments.

82.70.Dd - Colloids.
61.20.Ja - Computer simulation of liquid structure.
05.20.Jj - Statistical mechanics of classical fluids.

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