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Frequency-Dependent Shape Changes of Colloidal Clusters under Transverse Electric Field

Negi, Ajay Singh and Sengupta, Kheya and Sood, AK (2005) Frequency-Dependent Shape Changes of Colloidal Clusters under Transverse Electric Field. In: Langmuir, 21 (25). pp. 11623-11627.

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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 egimes. An increase in the particle size leads to a reduction in both Eth and fc. We present evidence o 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: Journal Article
Publication: Langmuir
Publisher: American Chemical Society
Additional Information: The Copyright belongs to American Chemical Society.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 06 Jan 2006
Last Modified: 19 Sep 2010 04:22
URI: http://eprints.iisc.ac.in/id/eprint/4869

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