Microabsorption Correction of X-Ray Intensities Diffracted by Multiphase Powder Specimens

Abstract

AbstractThe absorption of X-rays in a heterogeneous material depends on the linear absorption coefficients and volume fractions of the components, and on die geometrical peculiarities of their distribution. The latter is called the microabsorption effect, it can be separated into a bulk and a surface contribution. Within the framework of a well-defined stochastic structure model, the bulk contribution to the microabsorption is calculated for arbitrary random multiphase systems in terms of dependence on volume fractions and mean chord lengths of particles. Expressions are derived which are suitable for eliminating the experimental errors of scattering intensities caused by the bulk contribution of microabsorption.If only one wavelengtii of radiation is used, the mean chord lengths of the phases of the sample must be determined by other experimental techniques. A method is proposed to overcome this difficulty by using two or more wavelengths of radiation; this correction procedure works without the knowledge of the particle sizes of the phases.