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Title: Evolution of particle-scale dynamics in an aging clay suspension
Authors: Bandyopadhyay, Ranjini
Liang, Dennis
Yardimci, H.
Sessoms, D.A.
Issue Date: 2004
Publisher: American Physical Society
Citation: Physical Review Letters, 2002, vol93, p228302-1
Abstract: Multispeckle x-ray photon correlation spectroscopy was employed to characterize the slow dynamics of a colloidal suspension formed by highly-charged, nanometer-sized disks. At scattering wave vectors $q$ corresponding to interparticle length scales, the dynamic structure factor follows a form $f(q,t) \sim \exp[-(t/\tau)^{\beta}$], where $\beta \approx$ 1.5. The characteristic relaxation time $\tau$ increases with the sample age $t_a$ approximately as $\tau \sim t_a^{1.8}$ and decreases with $q$ approximately as $\tau \sim q^{-1}$. Such a compressed exponential decay with relaxation time that varies inversely with $q$ is consistent with recent models that describe the dynamics in disordered elastic media in terms of strain from random, local structural rearrangements. The amplitude of the measured decay in $f(q,t)$ varies with $q$ in a manner that implies caged particle motion at short times. The decrease in the range of this motion and an increase in suspension conductivity with increasing $t_a$ indicate a growth in the interparticle repulsion as the mechanism for internal stress development implied by the models.
Description: Open Access.
ISSN: 0031-9007
1079-7114 (Online)
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Copyright: 2004 American Physical Society
Appears in Collections:Research Papers (SCM)

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