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Analysis of High Angle Diffuse Scattering from Small Platelets

Published online by Cambridge University Press:  06 March 2019

A. D. Thomas Jr.  and
Gerald L. Liedl
A. D. Thomas Jr.
Affiliation:
University of Texas Austin, Texas
Gerald L. Liedl
Affiliation:
Purdue University Lafayette, Indiana
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Abstract

A detailed analysis of the high angle diffuse scattering from small platelets is given. A large number of statistically centrosymmetric platelets is considered, and it is shown that, in this cage, the positive square root of the diffuse intensity from the platelets is proportional to the amplitude of the scattered radiation over particular regions in reciprocal space. The measured amplitude distribution is truncated from the true amplitude distribution by the limits of measurement and the influence of Bragg scattering. A truncation function is introduced to describe this truncated amplitude distribution in terms of the true amplitude distribution. This truncation introduces modulations on the measured electron density distribution. The measured electron density distribution is described in terms of the convolution of the true electron density distribution and the transform of the truncation function. The transform of the truncation function is knowi analytically, so the true electron density distribution can be found by a relaxation method. The true electron density distribution is given in terms of composition and strain parameters which are independently adjusted during the relaxation procedure to fit the measured values. Examples of the influence of the truncation function arc given and the technique is applied to G–P 1 zones in an aluminum - 1.67 at % copper alloy.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 10: Fifteenth Annual Conference on Applications of X-ray Analysis, August 10-12, 1966 , 1966 , pp. 204 - 212
Copyright
Copyright © International Centre for Diffraction Data 1966

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References

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