MS43-05 - Texture Correction for Total Scattering Functions

Antonio Cervellino (Paul Scherrer Institut - Photon Science Division, Switzerland)

Preferred orientation (texture) is a complex effect that bridges powder diffraction to single crystal diffraction. Corrections for Bragg intensities are known [1-3]. However, within the Total Scattering approach, that prescinds from periodicity and therefore avoids ragg formalism, the problem of evaluating the S(Q) and G(r) scattering functions in the presence of texture has never been quantitatively tackled. A complete treatment in the framework of spherical harmonics for the most common powder diffraction experimental geometries is presented. The S(Q) can be computed by an extended version of the commonly used Debye scattering equation (DSE) [4] comprising now sums over spherical Bessel functions of all (even) orders. Selection rules arising from sample and experimental symmetries are given. Concerning the G(r), the effects of texture result in a fundamental indetermination that has important consequences. Example calculations for various interesting cases will be shown.As an aside, a second DSE-like formula for computing the antisymmetric intensity change in 3-D reciprocal space due to anomalous/resonant scattering is given. This is meant for single crystal or single particle studies. As with the DSE, this equation prescinds from spatial periodicity and can be used for non-crystalline matter.

1. J. Appl. Phys.36 (19650 2024
2. H.J. Bunge, Texture Analysis in Materials Science. Butterworth:London (1982) ISBN:0408104625
3. J. Appl. Cryst. 25 (1992) 611
4. Annalen der Physik 46 (1915) 809