Ostwald ripening and interparticle-diffraction effects for illite crystals

D. D. Eberl; J. Srodon

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USGS · 70014300

Ostwald ripening and interparticle-diffraction effects for illite crystals

D. D. Eberl·J. Srodon

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Abstract

The Warren-Averbach method, an X-ray diffraction (XRD) method used to measure mean particle thickness and particle-thickness distribution, is used to restudy sericite from the Silverton caldera. Apparent particle-thickness distributions indicate that the clays may have undergone Ostwald ripening and that this process has modified the K-Ar ages of the samples. The mechanism of Ostwald ripening can account for many of the features found for the hydrothermal alteration of illite. Expandabilities measured by the XRD peak-position method for illite/smectites (I/S) from various locations are smaller than expandabilities measured by transmission electron microscopy (TEM) and by the Warren-Averbach (W-A) method. This disparity is interpreted as being related to the presence of nonswelling basal surfaces that form the ends of stacks of illite particles (short-stack effect), stacks that, according to the theory of interparticle diffraction, diffract as coherent X-ray scattering domains. -from Authors

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D. D. Eberl, J. Srodon. 1988. Ostwald ripening and interparticle-diffraction effects for illite crystals. https://pubs.usgs.gov/publication/70014300

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