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Download fileEffect of pH on the Kinetics of Crystal Growth by Oriented Aggregation
journal contribution
posted on 19.02.2016, 01:43 authored by Nathan
D. Burrows, Christopher R.
H. Hale, R. Lee PennThe
kinetics of oriented aggregation are sensitive to solution
conditions, including pH. Decreasing the difference between solution
pH and the point of zero net proton charge results in an increasing
second-order rate constant for nonclassical crystal growth by oriented
aggregation. Results are discussed in the context of Derjaguin and
Landau, Verwey and Overbeek (DLVO) theory through the use of quantitative
statistical comparisons. The magnitude of the increase depends on
the primary particle size; however, the magnitude and trend in size
dependence deviate from predictions based on DLVO theory. Oriented
aggregation occurs in a wide array of important materials often resulting
in nanocrystals with unique, anisotropic, and symmetry-defying morphologies.
The growth of acicular goethite (α- FeOOH) was used as a model
system for this research. Transmission electron microscopy with time-resolved
sampling was employed using semiautomated image analysis to quantify
the rate constant for growth by oriented aggregation.