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Unsteady Crystal Growth Due to Step-Bunch CascadingBased on our experimental findings of growth rate fluctuations during the crystallization of the protein lysozym, we have developed a numerical model that combines diffusion in the bulk of a solution with diffusive transport to microscopic growth steps that propagate on a finite crystal facet. Nonlinearities in layer growth kinetics arising from step interaction by bulk and surface diffusion, and from step generation by surface nucleation, are taken into account. On evaluation of the model with properties characteristic for the solute transport, and the generation and propagation of steps in the lysozyme system, growth rate fluctuations of the same magnitude and characteristic time, as in the experiments, are obtained. The fluctuation time scale is large compared to that of step generation. Variations of the governing parameters of the model reveal that both the nonlinearity in step kinetics and mixed transport-kinetics control of the crystallization process are necessary conditions for the fluctuations. On a microscopic scale, the fluctuations are associated with a morphological instability of the vicinal face, in which a step bunch triggers a cascade of new step bunches through the microscopic interfacial supersaturation distribution.
Document ID
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Vekilov, Peter G.
(Alabama Univ. Huntsville, AL United States)
Lin, Hong
(Alabama Univ. Huntsville, AL United States)
Rosenberger, Franz
(Alabama Univ. Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
March 1, 1997
Publication Information
Publication: Physical Review E
Publisher: American Physical Society
Volume: 55
Issue: 3
ISSN: 1063-651X
Subject Category
Solid-State Physics
Funding Number(s)
Distribution Limits

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