Quantitative x-ray fluorescence analysis of (Ce, Tb)MgAl11O19 phosphors

In the X-ray fluorescence analysis of multicomponent samples by the empirical regression method, the influence coefficients aij are usually determined with the aid of multicomponent standards. However, it has been pointed out that these coefficients are not always effective for analyses of unknown samples. For instance, it has been reported that the coefficients aij are not applicable to analyze unknown samples which do not belong to the group of standards, and that the ''best fit'' set of values aij for unknown samples should be determined from standards which have compositions as close as possible to those of unknown samples. In this paper, the Criss and Birks method was applied to the analysis for (Ce, Tb) MgAl11O19 phosphors, on the consideration of aij described above. At first, therefore, an unknown sample was estimated by using the coefficients evaluated with the aid of a group of standards whose component elements are distributed over the wide range of contents. Second, the coefficients were re-determined from a group of standards having concentrations close to those of the tentative value of the sample, which resulted from those first estimated. Then the unknown sample was re-analyzed by using these coefficients. As a result, accuracies of the analytical values were improved compared with the first estimate, and concluded to be just as good for practical use. (author)