Frequency-dependent shape changes of colloidal clusters under transverse electric field

Negi, Ajay Singh ; Sengupta, Kheya ; Sood, A. K. (2005) Frequency-dependent shape changes of colloidal clusters under transverse electric field Langmuir, 21 (25). pp. 11623-11627. ISSN 0743-7463

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Official URL: http://pubs.acs.org/doi/abs/10.1021/la051258b

Related URL: http://dx.doi.org/10.1021/la051258b

Abstract

We have studied clustering of colloidal particles under the influence of an ac electric field as a function of frequency. The field was applied in a direction perpendicular to the confining walls. Two regimes are observed, a low frequency regime where the clusters are isotropic with a local triangular order, as reported earlier in the literature, and a new high-frequency regime where the clusters are highly elongated (anisotropic) with no local order. The crossover from one regime to the other occurs at a critical frequency, fc. The threshold field for the cluster formation, Eth, increases with frequency in both the regimes. An increase in the particle size leads to a reduction in both Eth and fc. We present evidence to show that the elongated structures seen at high frequency are related to the field inhomogeneities at imperfections on the conducting surface. We also propose a possible mechanism based on hydrodynamic flow considerations to explain the formation of these clusters.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:79878
Deposited On:30 Jan 2012 05:01
Last Modified:30 Jan 2012 05:01

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