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

TL;DR

This paper introduces a novel real space texture analysis method using 3D pair distribution functions to study fiber textured platinum films, enabling reconstruction of orientation distributions directly from diffraction data.

Contribution

It presents a new approach combining 3D PDF and real space analysis to determine texture and orientation distributions in nanostructured materials, with an open source software tool.

Findings

Successfully reconstructed the orientation distribution function of Pt film.

Defined a real space equivalent of pole figures using interatomic vectors.

Provided measurement guidelines for optimal isotropic PDF approximation.

Abstract

An approach is described for studying texture in nanostructured materials. The approach implements the real space texture PDF, txPDF, laid out in [Gong and Billinge (2018) arXiv:1805.10342 [cond-mat]]. It is demonstrated on a fiber textured polycrystalline Pt thin film. The approach uses 3D PDF methods to reconstruct the orientation distribution function (ODF) of the powder crystallites from a set of diffraction patterns taken at different tilt angles of the substrate with respect to the incident beam directly from the 3D PDF of the sample. A real space equivalent of the reciprocal space pole figure is defined in terms of interatomic vectors in the PDF and computed for various interatomic vectors in the Pt film. Further, it is shown how a valid isotropic PDF may be obtained from a weighted average over the tilt series, and the measurement conditions for the best approximant to the isotropic PDF from a single exposure, which for the case of the fiber textured film was in a nearly grazing incidence orientation of around 10 degrees. Finally, we describe an open source Python software package, Fourigui, that may be used to help in studies of texture from 3D reciprocal space data, and indeed for Fourier transforming and visualizing 3D PDF data in general.