A comparison of the effect of multiple scattering on first and second order X-ray diffraction from textured polycrystals, for the investigation of secondary extinction

Abstract

The integrated intensity of Debye-Scherrer (D-S) rings, arising from an eventual second diffraction process of a diffracted X-ray beam, was calculated. This represents the amount of intensity not arriving at the detector as oriented to register the first diffraction process, and as result, a measure of secondary extinction. Thus the objective is to investigate in this way if secondary extinction affects measurements of X-ray diffraction from textured polycrystals. This has been suggested by differences of pole density maxima observed between measured first and second order pole figures in strongly textured materials. Calculations are performed for a detector scan (varying only 2$ \theta $), and the integrated intensity is determined for first and second order diffraction conditions of a general plane ($hkl$). Normalization through corresponding powder is performed. It is found that this especial case of multiple scattering effect, indeed affects both orders essentially in the same way. If corresponding detector scan measurements verify this, then the observed differences between pole density maxima of pole figures of different order cannot be attributed to secondary extinction. Instead, they can be attributed to heterogeneous texture or error propagation. On the other hand, if the detector scans do exhibit a difference as that of pole density maxima, these differences can possibly be attributed to primary extinction.