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The Lorentz-Polarization Factor and Preferred Orientation in Oriented Clay Aggregates

Published online by Cambridge University Press:  02 April 2024

R. C. Reynolds Jr.
R. C. Reynolds Jr.*
Affiliation:
Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755
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Abstract

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A closed-form equation was derived that describes the powder-ring distribution factor as a function of 2θ, soller slit collimation, and σ*, which is defined as the standard deviation of an axially symmetrical Gaussian orientation function. Methods were developed for measuring σ* in the reflection mode by means of a θ/2θ diffractometer. Six experimental arrangements for a sedimentary chlorite showed widely different intensity ratios of the 001/005 reflections and gave a standard deviation of ±5.8% when corrected by the theory. The absolute integrated intensities of the 003 reflection from eleven illite samples provided an eight-fold maximum range which, when corrected, yielded a standard deviation of ±7.7%.

The intensity distributions within each of two X-ray powder diffraction patterns obtained from instruments with different soller-slit configurations could not be directly compared at low diffraction angles unless corrections, based on σ*, were introduced to allow for the differences in axial divergence.

Keywords

ChloriteIlliteIntensity distributionLorentz factorOrientationSoller slitsX-ray powder diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 34 , Issue 4 , August 1986 , pp. 359 - 367
Copyright
Copyright © 1986, The Clay Minerals Society

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