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Fundamental Parameters Line Profile Fitting in Laboratory Diffractometers

Published

Author(s)

R W. Cheary, A A. Coelho, James Cline

Abstract

The fundamental parameters approach to line profile fitting uses physically based models to generate the line profile shapes. Fundamental parameters profile fitting (FPPF) has been used to synthesize and fit data from both parallel beam and divergent beam diffractometers. The refined parameters are determined by the diffractometer configuration. In a divergent beam diffractometer these include the angular aperture of the divergence slit, the width and axial length of the receiving slit, the angular apertures of the axial Soller slits, the length and projected width of the x-ray source, the absorption coefficient and axial length of the sample. In a parallel beam system the principal parameters are the angular aperture of the equatorial analyser/Soller slits and the angular apertures of the axial Soller slits. The presence of a monochromator in the beam path is normally accommodated by modifying the wavelength spectrum and/or by changing one or more of the axial divergence parameters. Flat analyzer crystals have been incorporated into FPPF as a Lorentzian shaped angular acceptance function. One of the intrinsic benefits of the fundamental parameters approach is its adaptability any laboratory diffractometer. Good fits can normally be obtained over the whole 20 range without refinement using the known properties of the diffractometer, such as the slit sizes and diffractometer radius, and emission profile.
Proceedings Title
Special edition: Proceedings of Accuracy in Powder Diffraction III
Volume
109 No. 1
Conference Dates
April 1, 2001
Conference Location
Undefined
Conference Title
Accuracy in Powder Diffraction

Keywords

fundamental parameters, microstructure analysis, parafocusing optics, profile convolution, profile fitting, x-ray powder diffraction

Citation

Cheary, R. , Coelho, A. and Cline, J. (2004), Fundamental Parameters Line Profile Fitting in Laboratory Diffractometers, Special edition: Proceedings of Accuracy in Powder Diffraction III, Undefined (Accessed February 23, 2024)
Created January 31, 2004, Updated October 12, 2021