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The Fitting of Powder Diffraction Profiles to Ananalytical Express Ion and the Influence of Line Broadening Factors

Published online by Cambridge University Press:  06 March 2019

Allan Brown  and
J. W. Edmonds
Allan Brown
Affiliation:
Studsvik Energiteknik, S-611 82 Nyköping, Sweden
J. W. Edmonds
Affiliation:
Dow Chemical Company, Midland, MI 48640, USA
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Abstract

Powder diffraction profiles of well crystallized compounds can be fitted to distributions of the type Iθ=I°(1 + k2x2)-n where k is a scale factor related to the half width of the profile. The value of n varies with the diffraction angle, 2θ, and is generally different for the low-angle and high-angle sides of the same profile. Limiting values of n for a specific Guinier camera-micro-densitometer combination are 1.2 ≤ n ≤ 2.3. Similar values are obtained for diffracto meter profiles after Ktt2 stripping. Line broadening due to departure from perfect crystallinity in the specimen affects the value of n a swell as that of k.

The above observations are interpreted interms of the convolution of a Gaussian with a Lorentzian distribution, the exponent n of the convolute being dependent upon the relative half widths of these two functions, expressed as the ratio bL/bG.

Type
X-Ray Diffraction in Materials Analysis
Information
Advances in X-Ray Analysis , Volume 23: Twenty-Eighth Annual Conference on Applications of X-ray Analysis, July 30 - August 3, 1979 , 1979 , pp. 361 - 374
Copyright
Copyright © International Centre for Diffraction Data 1979

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