A new approach to synchrotron energy-dispersive X-ray diffraction computed tomography

Abstract

A new data collection strategy for performing synchrotron energy-dispersive X-ray diffraction computed tomography has been devised. This method is analogous to angle-dispersive X-ray diffraction whose diffraction signal originates from a line formed by intersection of the incident X-ray beam and the sample. Energy resolution is preserved by using a collimator which defines a small sampling voxel. This voxel is translated in a series of parallel straight lines covering the whole sample and the operation is repeated at different rotation angles, thus generating one diffraction pattern per translation and rotation step. The method has been tested by imaging a specially designed phantom object, devised to be a demanding validator for X-ray diffraction imaging. The relative strengths and weaknesses of the method have been analysed with respect to the classic angle-dispersive technique. The reconstruction accuracy of the method is good, although an absorption correction is required for lower energy diffraction because of the large path lengths involved. The spatial resolution is only limited to the width of the scanning beam owing to the novel collection strategy. The current temporal resolution is poor, with a scan taking several hours. The method is best suited to studying large objects (e.g. for engineering and materials science applications) because it does not suffer from diffraction peak broadening effects irrespective of the sample size, in contrast to the angle-dispersive case.

Pair distribution function computed tomography

“…Many of the heterogeneous devices that we desire to study under in situ or operando conditions, such as batteries, catalytic systems and fuel cells, contain important components that are nanocrystalline. Previous attempts to map amorphous or nanocrystalline components below B3 nm using XRD-CT were challenging requiring considerable a priori knowledge for the interpretation 13,18 . Traditionally, such materials are better studied using spectroscopic methods with, for example, recent techniques such as direct tomography with chemical bond contrast and/or (soft) transmission X-ray microscopy capable of providing the short-range order information necessary to image different amorphous or nanocrystalline components [19][20][21] .…”

Dark-field hyperspectral X-ray imaging

“…metals) sample cell walls or containment vessels essentially become transparent, making the method ideal for studying materials exposed to high temperatures or pressures. Furthermore, there are no sample size limitations associated with this method, which can be a constraint for scanning beam methods [28].…”

Diffraction/scattering computed tomography for three-dimensional characterization of multi-phase crystalline and amorphous materials

“…dispersive case, the energy-dispersive method does not suffer from peak broadening linked to the sample size and is therefore best suited to studying large objects from engineering and materials science applications (Lazzari et al, 2012). Palancher et al (2011) performed DSCT on low enriched nuclear fuels, which are very absorbent high-Z samples.…”