Experimental estimation of uncertainties in powder diffraction intensities with a two-dimensional X-ray detector

摘要

A method to obtain both one-dimensional powder diffraction intensities I(2) and statistical uncertainties sigma(2) from the data collected with a flat two-dimensional X-ray detector is proposed. The method has been applied to analysis of the diffraction data of fine quartz powder recorded with synchrotron X-ray. The profile and magnitude of the estimated uncertainties sigma(2) have shown that the effects of propagation of the errors in 2 are dominant as the uncertainties about the observed intensity values I(2). The powder diffraction intensity data I(2), including nine reflection peaks have been analyzed by the Rietveld method incorporating the experimentally estimated uncertainties sigma(2). The observed I(2) data have been reproduced with a symmetric peak profile function (R-wp = 0.84 %), and no significant peak shifts from calculated locations have been detected as compared with the experimental errors. The optimized values of the lattice constants of the quartz sample have nominally been estimated at a = 4.9131(4) angstrom and c = 5.4043(2) angstrom, where the uncertainties in parentheses are evaluated by the Rietveld optimization based on the estimated uncertainties sigma(2) for intensities I(2). It is likely that reliability of error estimation about unit-cell dimensions has been improved by this analytical method. (C) 2016 International Centre for Diffraction Data.