A multicomponent calibration approach to the microabsorption problem involving inorganic mixtures

Microabsorption may present a serious obstacle to performing accurate quantitative phase analysis by the Rietveld method for samples that contain phases with high X-ray absorption contrast. In this study, a multicomponent calibration approach is introduced to reduce the systematic bias that is not accounted for in conventional Rietveld analysis. In order to demonstrate this approach, six ternary inorganic mixtures containing components with diverse mass absorption coefficients were prepared. Two of the six mixtures were chosen as a calibration set to obtain the corresponding calibration parameters. These parameters were used to predict accurately the compositions of the remaining mixtures. Additionally, several other issues concerning sample preparation, the choice of the calibration set and the inclusion of complimentary techniques to determine the calibration parameters are addressed. The present approach offers practical advantages over the frequently used Brindley method, since it does not require any additional information concerning particle size and morphology.