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Calibration of the monochromator bandpass function for the X-ray Rietveld analysis

Published online by Cambridge University Press:  10 January 2013

P. Riello,
P. Canton and
G. Fagherazzi
P. Riello
Affiliation:
Dipartimento di Chimica Fisica, Università di Venezia, DD2137, 30123 Venezia, Italy
P. Canton
Affiliation:
Dipartimento di Chimica Fisica, Università di Venezia, DD2137, 30123 Venezia, Italy
G. Fagherazzi
Affiliation:
Dipartimento di Chimica Fisica, Università di Venezia, DD2137, 30123 Venezia, Italy
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Abstract

In this paper we propose a fitting procedure to describe the bandpass effect on all x radiation that passes through a focusing graphite monochromator used on the diffracted beam. The proposed bandpass function is: M(2θ)=1/(1+Kmon1sKmon2), with s=(2 sin θ)/λ, where Kmon1 and Kmon2 are constants which have been refined by means of a Rietveld analysis, using a physically modeled background (Riello et al., J. Appl. Crystallogr. 28, 115–120). We have investigated two polycrystalline powders: α-Al2O3 and a mixture of α and β-Si3N4. The so-obtained bandpass functions for these materials are close enough to conclude that they depend only on the used experimental setup (in the present case the X-Pert-Philips diffractometer with a graphite focusing monochromator). Knowledge of the bandpass function is important to suitably model the Compton scattering, which is a component of the background scattering. The present procedure allows one to avoid the direct experimental determination of the bandpass function, which requires the use of another monochromator (analyzer) and another tube with an intense white spectrum.

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Type
Research Article
Information
Powder Diffraction , Volume 12 , Issue 3 , September 1997, pp. 160 - 166
Copyright
Copyright © Cambridge University Press 1997

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