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Recognition and Treatment of Background Problems in Neutron Powder Diffraction Refinements

Published online by Cambridge University Press:  06 March 2019

W. H. Baur  and
R. X. Fischer
W. H. Baur
Affiliation:
Department of Geological Sciences , Box 4348 University of Illinois at Chicago, ChicagoIllinois 60680
R. X. Fischer
Affiliation:
Department of Geological Sciences , Box 4348 University of Illinois at Chicago, ChicagoIllinois 60680
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Abstract

Irregular backgrounds in time-of-flight neutron powder diffraction data and nonlinear backgrounds in angle dependent neutron powder diffraction data. were corrected by fitting fifth degree polynomials to those portions of the data most affected. The anomalous background intensities were in both cases due to non Bragg scattering. The polynomial fitting was carried out over a sufficiently widerange of the profile to avoid interfering with the Bragg peaks. The corrected data gave internally consistent results for the crystallographically nonequivalent (Si,Al) -0 (1) and(Si, Al) -0 (2) bond lengths in zeolite rho and compare favorably with previous refinements of this Zeolite in space group Im3m. Internal and external in consistencies of bond lengths are just as diagnostic of refinement difficulties as negative isotropic temperature factors or non positive definite an isotropic temperature factors are.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 29: Thirty-Fourth Annual Conference on Applications of X-ray Analysis, August 5-9, 1985 , 1985 , pp. 131 - 142
Copyright
Copyright © International Centre for Diffraction Data 1985

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