Texture corrections for total scattering functions

Abstract

Many functional materials are today synthesized in the form of nanoparticles displaying preferred orientation effects to some small or large extent. The analysis of diffraction data of such kinds of systems is best performed in the framework of the total scattering approach that prescinds from translation symmetry assumptions. Therefore modified expressions were derived for the most common total scattering functions, in particular the Debye scattering equation (DSE) which yields the texture-averaged differential cross section as a function of atomic coordinates and texture parameters. The modified DSE encodes higher-order even spherical Bessel functions which account for the texture effect. Selection rules arising from experimental geometries and symmetries are discussed. In addition the duality of the texture effect is introduced showing the effects of texture on both the I(Q) and GðrÞ. The paper includes several definitions and appendices which are meant to be useful for those involved in the development of crystallographic computing.

Structural Analysis of Molecular Materials Using the Pair Distribution Function

“…Thus, the techniques as used for typical PDF analysis are more suited toward amorphous and nanoscale polycrystalline films. In cases where the films have much larger domains, or are subject to severe preferred orientation, different methods for data reduction and analysis will be necessary, and new methods are being developed for handling this. ,, …”

Real space texture and pole figure analysis using the three-dimensional pair distribution function (PDF) on a Platinum thin film

“…In favorable circumstances, texture related intensity changes in Bragg peaks can be modelled in a Rietveld refinement (Gilmore & Schenk, 2019). This is less well developed in real-space refinements, though for weak textures, a model has been pro-posed (Cervellino & Frison, 2020). Here we explore whether sufficiently texture-free PDFs, which can then be refined in existing PDF modeling programs such as PDFgui (Farrow et al, 2007), can be obtained by averaging data collected at different sample angles.…”

“…This would allow, in principle, the determination of oriental distribution functions that encode the texture directly in real-space, which may be favorable if the powder grains are nanocrystalline. In the case of weakly textured samples, equations have also been derived to correct the Debye scattering equation for texture information (Cervellino & Frison, 2020).…”

Preferred orientation and its effects on intensity-correlation measurements

“…Typically, disordered materials have been studied through the analysis of the 'total scattering structure factor' and its Fourier transform, the pair distribution function (PDF). This highly successful approach has been applied to a wide array of materials taking advantage of advances in instrumentation and modelling techniques, including development of texture analysis (Paddison, 2019;Dippel et al, 2019;Cervellino & Frison, 2020). Fluctuation X-ray scattering (FXS) is an alternative approach for probing disordered structure (Kam, 1977;Kam et al, 1981;Treacy et al, 2005) that aims to go beyond pair statistics and recover information about local angular structure.…”