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Title: Frequency-dependent shape changes of colloidal clusters under transverse electric field
Authors: Negi, A.S.
Sengupta, Kheya
Sood, A.K.
Issue Date: 9-Nov-2005
Publisher: American Chemical Society
Citation: Langmuir, 2005, Vol. 21, p11623-11627
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.
Description: Restricted Access.
ISSN: 0743-7463
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Copyright: 2005 American Chemical Society
Appears in Collections:Research Papers (SCM)

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