Cluster kinetics and dynamics during spinodal decomposition

Yang, Jiao and McCoy, Benjamin J and Madras, Giridhar (2006) Cluster kinetics and dynamics during spinodal decomposition. In: Journal of Chemical Physics, 124 (2).

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Abstract

Spinodal decomposition (barrierless phase transition) is a spontaneous phase separation caused by conditions that force the system to become thermodynamically unstable. We consider spinodal decomposition to occur under conditions of large supersaturation S and/or small ratio of interfacial to thermal energies \omega, such that the computed number of monomers in a critical nucleus $\epsilon *=( \omega/ ln S)^{3}$ is less than unity. The small critical nucleus size is consistent with a negligible energy barrier for initiating condensation. Thus, in contrast to conventional opinion, it is suggested that the spinodal ecomposition is related to the homogeneous nucleation of metastable fluids. Population balance equations show how clusters aggregate and rapidly lead to phase separation. Different mass dependences of aggregation rate coefficients are proposed to investigate the fundamental features of spinodal decomposition. When the mass dependency is an integer, the equations are solved by the moment technique to obtain analytical solutions. When the mass dependency is a noninteger, the general cases are solved numerically. All solutions predict the two time regimes observed experimentally: the average length scale of condensed-phase domains increases as a power law with an exponent of 1/3 at early times, followed by a linear increase at longer times.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
Publisher:	American Institute of Physics
Additional Information:	Copyright for this article belongs to American Institute of Physics.
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	28 Feb 2006
Last Modified:	19 Sep 2010 04:24
URI:	http://eprints.iisc.ac.in/id/eprint/5746

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