Quantitative analysis of multicomponent powders by full-profile refinement of Guinier–Hägg X-ray film data

Full-profile analysis of microdensitometer-measured Guinier–Hägg X-ray powder film data (strictly monochromatized Cu Kα₁ radiation) [see Malmros & Thomas (1977). J. Appl. Cryst. 10, 7–11] is here extended to treat a multicomponent system where two of the components are refinable. The method is demonstrated for the case of: (a) α-Bi₂O₃/KCl (standard), and (b) CaF₂/SiO₂ (α-quartz) together with a Mg(OH)₂ matrix. In (a), a weight ratio Bi₂O₃/KCl of 1:1 gave an experimental result of 0.96 (9):1. In (b), a number of admixtures have been studied in the range 1–60 wt% SiO₂ all with 10 wt% CaF₂. The agreement between weight ratios and profile refinement results suggests that the formal temperature factors function as effective absorption correction parameters. It is thus shown that approximate quantitative analysis is feasible from Guinier-Hägg diffraction data without any previously determined calibration curve. Moreover, the method permits the use of all available overlapping data in the refinement of a structure without needing to exclude data from known impurities [see Waltersson, Werner & Wilhelmi (1977). Cryst. Struct. Commun. 6, 231–235]. This feature is likely to prove the most common application of the method.