High-resolution X-ray diffraction with no sample preparation

Abstract

It is shown that energy-dispersive X-ray diffraction (EDXRD) implemented in a back-reflection geometry is extremely insensitive to sample morphology and positioning even in a high-resolution configuration. This technique allows highquality X-ray diffraction analysis of samples that have not been prepared and is therefore completely non-destructive. The experimental technique was implemented on beamline B18 at the Diamond Light Source synchrotron in Oxfordshire, UK. The majority of the experiments in this study were performed with pre-characterized geological materials in order to elucidate the characteristics of this novel technique and to develop the analysis methods. Results are presented that demonstrate phase identification, the derivation of precise unitcell parameters and extraction of microstructural information on unprepared rock samples and other sample types. A particular highlight was the identification of a specific polytype of a muscovite in an unprepared mica schist sample, avoiding the time-consuming and difficult preparation steps normally required to make this type of identification. The technique was also demonstrated in application to a small number of fossil and archaeological samples. Back-reflection EDXRD implemented in a high-resolution configuration shows great potential in the crystallographic analysis of cultural heritage artefacts for the purposes of scientific research such as provenancing, as well as contributing to the formulation of conservation strategies. Possibilities for moving the technique from the synchrotron into museums are discussed. The avoidance of the need to extract samples from high-value and rare objects is a highly significant advantage, applicable also in other potential research areas such as palaeontology, and the study of meteorites and planetary materials brought to Earth by sample-return missions.

Hexagonal Molybdenum Trioxide (h‐MoO3) as an Electrode Material for Rechargeable Aqueous Aluminum‐Ion Batteries

“…Samples mounted on a stainless‐steel substrate (MTI Corp) were used for XRD analysis. A Rigaku SmartLab diffractometer (Cu source, 40 kV 40 mA) was employed to obtain Powder X‐ray diffraction patterns in parallel beam (PB) geometry (which virtually eliminates well‐known instrument error functions, which contribute to asymmetric peak broadening, such as rough or non‐flat samples, axial divergence, and sample transparency) with an incident slit of 0.8 mm and receiving slit of 20 mm with a Hypix 3000 detector. XRD patterns were obtained over a range of 2–80° with 2θ at a step size of 0.01°.…”

A prototype handheld X-ray diffraction instrument

“…Other application areas are feasible and a particularly interesting example is the field of cultural heritage (Hansford et al, 2017). Naturally, a very wide range of materials are encountered in the field as a whole and the use of HHXRD would need to be targeted to specific material types such as metallic artefacts.…”

“…Energy-dispersive X-ray diffraction (EDXRD) in a backreflection geometry is uniquely insensitive to sample morphology and to the precise distance between instrument and sample (Hansford, 2011(Hansford, , 2013Hansford et al, 2014Hansford et al, , 2017. If the sample is also fine grained such that the powder-averaging criterion is satisfied, then an XRD analysis can be performed with no sample preparation at all.…”

“…A key limitation of EDXRD is the relatively low resolution afforded by energy-dispersive detectors, confining studies to materials which are not too crystallographically complex. Only a small number of synchrotron EDXRD experiments that use the high resolution offered by scanning monochromators have been reported (Bourdillon et al, 1978;Parrish & Hart, 1987), including the related work of the author (Hansford et al, 2017). The majority of EDXRD experiments use synchrotron radiation to access high flux at high energies, but some laboratory instruments have been developed to take advantage of the static geometry (Dicken et al, 2015;O'Dwyer et al, 2014;Garrity et al, 2007).…”

High-resolution non-invasive X-ray diffraction analysis of artists’ paints

“…If the energy-dispersion is provided by the X-ray detector the method has quite low resolution, usually the main drawback. However, one method to overcome this limitation is to scan through a range of highly monochromatic X-ray energies at a synchrotron facility [25][26][27] in which case the resolution is limited by the monochromator bandpass and the geometry adopted. Back-reflection EDXRD [27,28] offers a method to achieve high resolution together with essentially no dependence on surface morphology, a highly beneficial combination in the context of archaeometry studies.…”