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Analytical method for observed powder diffraction intensity data based on maximum likelihood estimation

Published online by Cambridge University Press:  16 April 2013

Takashi Ida  and
Fujio Izumi
Takashi Ida*
Affiliation:
Advanced Ceramics Research Center, Nagoya Institute of Technology, Nagoya, Japan
Fujio Izumi
Affiliation:
National Institute for Materials Science, Ibaraki, Japan
*
a)Author to whom correspondence should be addressed. Electronic mail: ida@ida.takashi@nitech.ac.jp
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Abstract

A new methodology based on maximum likelihood estimation for structure refinement using powder diffraction data is proposed. The method can not only optimize the parameters adjusted in Rietveld refinement but also parameters to specify errors in a model for statistical properties of the observed intensity. The results of structure refinements with relation to fluorapatite Ca5(PO4)3F, anglesite PbSO4, and barite BaSO4 are demonstrated. The structure parameters of fluorapatite and barite optimized by the new method are closer to single-crystal data than those optimized by the Rietveld method, while the structure parameters of anglesite, whose values optimized by the Rietveld method are already in good agreement with the single-crystal data, are almost unchanged by the application of the new method.

Keywords

powder diffraction datacrystal structureRietveld refinementmaximum likelihood estimationfluorapatiteanglesitebarite

Information

Type
Technical Articles
Information
Powder Diffraction , Volume 28 , Issue 2 , June 2013 , pp. 124 - 126
Copyright
Copyright © International Centre for Diffraction Data 2013 

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