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An experimental investigation of the effects of axial divergence on diffraction line profiles

Published online by Cambridge University Press:  10 January 2013

R. W. Cheary  and
A. A. Coelho
R. W. Cheary
Affiliation:
Department of Applied Physics, University of Technology Sydney, P.O. Box 123, Broadway, New South Wales, 2007, Australia
A. A. Coelho
Affiliation:
CSIRO Minerals, P.O. Box 124, Port Melbourne, Victoria, 3207, Australia
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Abstract

An experimental investigation has been carried out to determine the extent to which axial divergence in a conventional powder diffractometer influences the measurement of peak profile parameters. A Siemens D5000 θ–2θ diffractometer was used for this study along with the LaB6 line profile standard SRM 660. Eight unique levels of axial divergence were investigated either by removing one or more of the Soller slits, or by introducing different combinations of Soller slits in the incident and diffracted beams. The measure of axial divergence used throughout is based on the maximum axial divergences of the incident and diffracted beams, Ψi and Ψd. Axial divergence produces a small and almost constant shift δ2θp in the peak angle which in a typical diffractometer would amount to a zero offset 2θ≈0.005°. The integrated intensity of a profile increases almost linearly with the product Ψi*Ψd. The increase in breadth in profiles in the angular region 2θ<120° arises mainly from the change in asymmetry DH=Hlo−Hhi in which one side of the profile broadens (i.e., either the high angle or low angle side) without any significant broadening of the other side. Moreover, the asymmetry DH is linearly dependent on 2θ for a fixed level of axial divergence, and linearly dependent on the total axial divergence Ψi+Ψd at fixed 2θ.

Keywords

X-ray diffractometersaxial divergenceline profile analysis
Type
Research Article
Information
Powder Diffraction , Volume 13 , Issue 2 , June 1998 , pp. 100 - 106
Copyright
Copyright © Cambridge University Press 1998

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