ANALYSIS OF THE UNCERTAINTIES OF THE QUANTITATIVE PHASE ANALYSIS BY X-RAY POWDER DIFFRACTION BASED ON THE RIETVELD METHOD / ANÁLISE DAS INCERTEZAS DA QUANTIFICAÇÃO DE FASE PELO MÉTODO DE RIETVELD EM ANÁLISE DE PÓ POR DIFRAÇÃO DE RAIOS X

AUTOR(ES)

TEREZINHA FERREIRA DE OLIVEIRA

DATA DE PUBLICAÇÃO

2005

RESUMO

The analysis of measurement systems is done by the examination of the adequacy of the system according to the operator, the instrument and other sources of variability, as well as by the comparison of the measurement error variance with the natural process variance. This research consisted in the evaluation of the uncertainties of phase quantification in powder analysis by the Rietveld method. The evaluation of the effects of several factors on the phase quantification was performed using statistical techniques of design of experiments and of multivariate analysis, with the use of materials of high level of traceability for the conduction of the experiments, in the Laboratory of X-ray Diffraction of the Pontifícia Universidade Católica do Rio de Janeiro. Through the determination of the variational structure of the process it was verified that the analyzed phases suffer influence of the measurement conditions in a differentiated way, which prevents the obtention of a general formula for calculation of the quantification error, although the errors can be determined by a repeatability and reproducibility analysis properly conducted.

ASSUNTO(S)

statistical methods chemical metrology rietveld method metodo de rietveld quantitative phase analysis metrologia quimica incerteza de medicao validation of analytical methods validacao de metodos analiticos metodos estatisticos analise quantitativa de fase uncertainty of analytical results

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