Multimodal x-ray imaging techniques reveal insight into the structure-function relationships in cobalt Fischer-Tropsch catalysts.

X-ray diffraction computed tomography (XRD-CT) has been used to identify the nature of crystalline surface deposits in Rembrandt's Homer.

X-ray computed tomography (XCT) was used to nondestructively observe the hidden corrosion damage operando on aluminum alloy (AA) 7050-T7451 coupled to stainless steel (SS) 304 under a droplet of chloride-containing electrolyte. XCT enabled a three-dimensional assessment of corrosion damage evolution. AA7050 cylinders containing concentric embedded SS304 cylinders simulating a fastener were exposed under NaCl droplets at 97% RH for various times. Both the volume of corrosion damage and the initial volume of constituent particles were monitored and considered for further analysis. Three-dimensional image reconstruction indicated that the combination of stainless steel and constituent particles could support the growth of several corrosion fissures over the exposure period. KEY WORDS: aluminum alloy 7050, galvanic corrosion, simulated fastener, x-ray computed tomography ISSN 0010-9312 (print), 1938-159X (online) 15/000189/$5.00+$0.50/0 © 2015, NACE International

We employ a novel combination of a Fresnel lens and a diffuser for x-ray ptychography. The setup uses increased flux by enlarging the width of the coherence-defining slits upstream of the experimental station. In the reconstruction algorithm, modal decomposition is used to account for the resulting partial coherence in the beam. We show that if the object has sparse feactures and large areas of flat contrast, the diffuser facilitates a better reconstruction and the extra diversity in the data also allows cleaner separation of the constituent modes in the illumination. The setup also allows a quick, real-time measure of the beam coherence.

The aim of this work is using Bragg coherent X-ray diffraction imaging (BCDI) to study the calcite crystallization during carbonation of hydrated tricalcium silicate (C3S). Portland cement is a very complex synthesized product whose 50~70% mass is composed of C3S, which is the most important phase to produce calcium silicate hydrates and calcium hydroxide. Hence, its hydration contributes greatly to the hydration of cement and later to the carbonation of cement products when it reacts with CO2, often from the air, to form calcium carbonates. BCDI has emerged in the last decade as a promising high-resolution lens-less imaging approach for characterization of various samples. It has made significant progress with the development of Xray sources and phase-retrieval algorithms. BCDI allows for imaging the whole three-dimensional structure of micro-and sub-micro-crystalline materials and can show the strain distribution at the nanometer spatial resolution. Results show that calcite crystallization follows a through-solution reaction and the growth model of the calcite crystal can be explained by using "phase domain" theory. During carbonation, calcite crystals grow by increasing the number of phase domains within them while the domain size remains at about 200~300nm.

With the development of fourth-generation high-brightness synchrotrons on the horizon, the already large volume of data that will be collected on imaging and mapping beamlines is set to increase by orders of magnitude. As such, an easy and accessible way of dealing with such large datasets as quickly as possible is required in order to be able to address the core scientific problems during the experimental data collection. Savu is an accessible and flexible big data processing framework that is able to deal with both the variety and the volume of data of multimodal and multidimensional scientific datasets output such as those from chemical tomography experiments on the I18 microfocus scanning beamline at Diamond Light Source.

Multiferroic materials that exhibit coupling between ferroelectric and magnetic properties are of considerable utility for technological applications and are also interesting from a fundamental standpoint. When reduced to the nanoscale, multiferroic materials often display additional functionality that is dominated by interfacial and confinement effects. Bismuth ferrite (BiFeO 3 ) is one such material with room temperature anti-ferromagnetic and ferroelectric ordering. Optical excitation of BiFeO 3 crystals results in an elastic structural deformation of the lattice with a fast response on the pico-second time scale. Here we report on dynamic measurements to investigate the structural properties of BiFeO 3 nanoscale crystals using laser excitation and three-dimensional Bragg coherent x-ray diffraction imaging. Tensile strain beyond 8´-10 2 was observed predominantly at the surface of the nanoscale crystal as evidenced in the reconstructed phase information and was correlated to photo-induced lattice deformation.

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