Search

To improve lithium and sodium ion battery technology, it is imperative to understand how the properties of the different components are controlled by their chemical structures. Operando structural studies give us some of the most useful information for understanding how batteries work, but it remains difficult to separate out the contributions of the various components of a battery stack (e.g., electrodes, current collectors, electrolyte, and binders) and examine specific materials. We have used operando X-ray diffraction computed tomography (XRD-CT) to study specific components of an essentially unmodified working cell and extract detailed, space-resolved structural information on both crystalline and amorphous phases that are present during cycling by Rietveld and pair distribution function (PDF) methods. We illustrate this method with the first detailed structural examination of the cycling of sodium in a phosphorus anode, revealing surprisingly different mechanisms for sodiation and desodiation in this promising, high-capacity anode system. [ABSTRACT FROM AUTHOR]

To improve lithium and sodium ion battery technology, it is imperative to understand how the properties of the different components are controlled by their chemical structures. Operando structural studies give us some of the most useful information for understanding how batteries work, but it remains difficult to separate out the contributions of the various components of a battery stack (e.g., electrodes, current collectors, electrolyte, and binders) and examine specific materials. We have used operando X-ray diffraction computed tomography (XRD-CT) to study specific components of an essentially unmodified working cell and extract detailed, space-resolved structural information on both crystalline and amorphous phases that are present during cycling by Rietveld and pair distribution function (PDF) methods. We illustrate this method with the first detailed structural examination of the cycling of sodium in a phosphorus anode, revealing surprisingly different mechanisms for sodiation and desodiation in this promising, high-capacity anode system. [ABSTRACT FROM AUTHOR]

Structure-sensitive catalyzed reactions can be influenced by a number of parameters. So far, it has been established that the formation of Pd-C species is responsible for the behavior of Pd nanoparticles employed as catalysts in a butadiene partial hydrogenation reaction. In this study, we introduce some experimental evidence indicating that subsurface Pd hydride species are governing the reactivity of this reaction. In particular, we detect that the extent of formation/decomposition of PdHx species is very sensitive to the Pd nanoparticle aggregate dimensions, and this finally controls the selectivity in this process. The main and direct methodology applied to determine this reaction mechanism step is time-resolved high-energy X-ray diffraction (HEXRD). [ABSTRACT FROM AUTHOR]

Abstract: The features associated with modern synchrotron radiation machines (intense and coherent beams) result in a substantial extension of X-ray imaging capabilities in terms of spatial and temporal resolution, phase contrast and 3D images. This allows crystal growth-related information to be obtained which is not available otherwise. After briefly describing the main synchrotron radiation based imaging techniques of interest, we give original examples illustrating the new capabilities for crystal growth: characterisation of crystals grown for applications, such as ice tri-crystals produced for mechanical deformation studies; SiC; crystalline silicon for solar photovoltaic cells; in situ and in real time studies of quasicrystal growth (AlPdMn); and ultrafast tomography for the study of the growth of dendrites in metallic alloys. [Copyright &y& Elsevier]

The high flux of high energy X-rays that can be provided through state-of-the-art high energy synchrotron beam lines has enabled a variety of new experiments with the highly absorbing Nb3Sn superconductors. We report different experiments with Nb3Sn strands that have been conducted at the ID15 High Energy Scattering beam line of the European Synchrotron Radiation Facility (ESRF). Synchrotron X-ray diffraction has been used in order to monitor phase transformations during in-situ reaction heat treatments prior to Nb3Sn formation, and to monitor Nb3Sn growth. Fast synchrotron micro-tomography was applied to study void growth during the reaction heat treatment of Internal Tin strands. The elastic strain in the different phases of fully reacted Nb3Sn composite conductors has been measured by high resolution X-ray diffraction during in-situ tensile tests. [ABSTRACT FROM AUTHOR]

The anomalous scattering properties of innate sulfur for proteins and phosphorus for DNA and RNA can be used to solve the phase problem in macromolecular crystallography (MX) via the single-wavelength anomalous dispersion method (SAD). However, this method, which is carried out at longer X-ray wavelengths (1.5-2.5 Å), is still not a routine tool in MX. The increased absorption from both air and sample associated with the use of longer X-ray wavelengths presents a key difficulty. The absorption can be corrected for through empirical algorithms, provided truly redundant data are available. Unfortunately, weakly diffracting macromolecular crystals suffer from radiation damage, resulting in a dose-dependent non-isomorphism which violates the assumption upon which these empirical algorithms are based. In this report, X-ray microtomography is used to reconstruct the three-dimensional shapes of vitrified macromolecular crystals including the surrounding solvent and sample holder. The setup can be integrated within an MX beamline environment and exploits both absorption and phase contrast. The dose needed for the tomographic measurements could be low enough to allow the technique to be used for crystal integrity characterization and alignment. X-ray tomography has some major benefits compared with the optical-light-based crystal alignment protocols currently used. [ABSTRACT FROM AUTHOR]

The phase transformations that occur during the reaction heat treatment (HT) of Nb3Sn superconductors depend on the overall elemental composition of the strand subelements. In the case of modern high Jc strands with a relatively low Cu content, liquid phases are present during large temperature intervals and phases that can be detrimental for the microstructural and microchemical homogeneity of the fully reacted strand are formed. We report synchrotron X-ray diffraction measurements during in-situ reaction HT of a state-of-the-art high Jc Nb3Sn internal tin strand. In this strand, Cu3 Sn is formed upon Cu6 Sn5 decomposition at 415 °C, a Sn-rich ternary Cu-Nb-Sn phase is detected in the approximate temperature interval 345 °C-575 °C, and NbSn2 is present in the temperature interval 545 °C-630 °C. The formation of voids in the strand subelements has been monitored by synchrotron microtomography during in-situ reaction HT. [ABSTRACT FROM AUTHOR]

Abstract: A Monte Carlo Ray Tracing program has been developed to predict the thermal radiative properties of an X-ray microtomographic reconstructed silica glass containing gas bubbles, for a large domain of wavelength (1–25μm) and for a large domain of temperature (300–1500K). The main input of the program is the complex optical index of the corresponding homogeneous silica glass. Validity of the model is checked by comparing a simulated normal spectral emittance, obtained on the reconstructed glass, with the experimental one recorded at . [Copyright &y& Elsevier]

Single-wavelength anomalous diffraction (SAD), multiwavelength anomalous diffraction (MAD) and single isomorphous replacement with anomalous scattering (SIRAS) phasing at ultra-high X-ray energy, 55 keV, are used successfully to determine a high-quality and high-resolution experimental electronic density map of hen egg-white lysozyme, a model protein. Several combinations, between single- and three-wavelength, with native data were exploited to demonstrate that standard phasing procedures with standard equipment and software can successfully be applied to three-dimensional crystal structure determination of a macromolecule, even at these very short wavelengths. For the first time, a high-quality three-dimensional molecular structure is reported from SAD phasing with ultra-high-energy X-rays. The quality of the crystallographic data and the experimental electron density maps meet current standards. The 2.7% anomalous signal from three Ho atoms, at the Ho K edge, was sufficient to obtain a remarkable electron density and build the first lanthanide structure for HEWL in its entirety. [ABSTRACT FROM AUTHOR]

At the High Energy Beamline ID15A at the European Synchrotron Radiation Facility we have developed a fast three-dimensional x-ray microtomography system, which acquires a complete dataset in typically less than 10 s. This unprecedented speed is achieved by combining a high efficiency phosphor screen, a reflecting microscope objective and a fast charge coupled device detector with the very intense high-energy white beam radiation provided by a wiggler source. The achieved spatial resolution is 2 μm. The available x-ray energy spectrum spans from 20 to 250 keV and can therefore be used for low and high Z materials. The spectrum can be modified by inserting different filters into the x-ray beam in order to optimize the signal-to-noise ratio and to avoid beam-hardening artifacts. Different phosphors with different energy sensitivity can be used. The very high speed allows in situ studies of systems evolving on the time scale of a few seconds or minutes. Three examples are given on sintering of metallic powders, solidification of binary alloys and liquid front propagation in granular materials. [ABSTRACT FROM AUTHOR]

The article presents a study which crystallizes CO dissociation and transient carbon storage by Pd nanoparticles through combining diffuse resistance infrared spectroscopy (DRIFTS) and time-resolved hard X-ray diffraction (HRXD). It states that the method allows specification of Al2O3-supported Pd nanoparticles actively participating in de-NOx chemistry. It mentions that method also helped in the discovery of the fundamental events in nanoparticulate catalysis.

The Extremely Brilliant Source (EBS) is the experimental implementation of the novel Hybrid Multi Bend Achromat (HMBA) storage ring magnetic lattice concept, which has been realised at European Synchrotron Radiation Facility. We present its successful commissioning and first operation. We highlight the strengths of the HMBA design and compare them to the previous designs, on which most operational synchrotron X-ray sources are based. We report on the EBS storage ring's significantly improved horizontal electron beam emittance and other key beam parameters. EBS extends the reach of synchrotron X-ray science confirming the HMBA concept for future facility upgrades and new constructions. X-ray science at modern Synchrotrons and X-ray Free Electron Laser facilities are enabling the study of subtle structural changes of matter from the single atom to the macroscopic scale. This paper reviews new concepts in synchrotron storage rings design and reports on the successful commissioning and operation of the new X-ray storage ring of the European Synchrotron Radiation Facility (ESRF) in Grenoble. [ABSTRACT FROM AUTHOR]

Lateral chromatic aberration in microscopy based on refractive optics may be reduced significantly by adjustments to the illumination scheme. By taking advantage of a broadened bandwidth illumination, the proposed scheme could open for x-ray microscopy with spatial resolution in the range 150-200 nm at millisecond frame rates. The scheme is readily implemented and is achievable using only standard refractive x-ray lenses, which has the advantage of high efficiency. It also maximizes the transmission and removes the spatial filtering effects associated with absorption in x-ray lenses. [ABSTRACT FROM AUTHOR]

High-pressure high-temperature syntheses that involve volatile-bearing aqueous fluids are typically accomplished by enclosing the samples in gas-tight welded shut noble-metal capsules, from which the bulk volatile content must be extracted to be analyzed with mass spectroscopy, hence making the analysis non-replicable. Here we describe a novel non-destructive method that ensures the identification and the quantitative estimate of the volatiles directly in the sealed capsule, focusing on fluid H2O–CO2 mixtures equilibrated with graphite at conditions of geological interest (1 GPa, 800 °C). We used a high-energy (77 keV) synchrotron X-ray radiation combined with a cryostat to produce X-ray diffraction patterns and X-ray diffraction microtomographic cross-sections of the volatile-bearing samples down to –180 °C, thus encompassing the conditions at which crystalline phases-solid CO2 and clathrate (CO2 hydrate)-form. The uncertainty of the method is < 15 mol%, which reflects the difference between the volatile proportion estimated by both Rietveld refinement of the diffraction data and by image analysis of the microtomograms, and the reference value measured by quadrupole mass spectrometry. Therefore, our method can be reliably applied to the analysis of frozen H2O–CO2 mixtures and, moreover, has the potential to be extended to experimental fluids of geological interest containing other volatiles, such as CH4, SO2 and H2S. [ABSTRACT FROM AUTHOR]

Some mollusc shells are formed from an amorphous calcium carbonate (ACC) compound, which further transforms into a crystalline material. The transformation mechanism is not fully understood but is however crucial to develop bioinspired synthetic biomineralization strategies or accurate marine biomineral proxies for geoscience. The difficulty arises from the simultaneous presence of crystalline and amorphous compounds in the shell, which complicates the selective experimental characterization of the amorphous fraction. Here, we use nanobeam X-ray total scattering together with an approach to separate crystalline and amorphous scattering contributions to obtain the spatially resolved atomic pair distribution function (PDF). We resolve three distinct amorphous calcium carbonate compounds, present in the shell of Pinctada margaritifera and attributed to: interprismatic periostracum, young mineralizing units, and mature mineralizing units. From this, we extract accurate bond parameters by reverse Monte Carlo (RMC) modeling of the PDF. This shows that the three amorphous compounds differ mostly in their Ca–O nearest-neighbor atom pair distance. Further characterization with conventional spectroscopic techniques unveils the presence of Mg in the shell and shows Mg–calcite in the final, crystallized shell. In line with recent literature, we propose that the amorphous-to-crystal transition is mediated by the presence of Mg. The transition occurs through the decomposition of the initial Mg-rich precursor into a second Mg-poor ACC compound before forming a crystal. [ABSTRACT FROM AUTHOR]

Millimetre-sized primordial rock fragments originating from asteroid Ryugu were investigated using high energy X-ray fluorescence spectroscopy, providing 2D and 3D elemental distribution and quantitative composition information on the microscopic level. Samples were collected in two phases from two sites on asteroid Ryugu and safely returned to Earth by JAXA's asteroid explorer Hayabusa2, during which time the collected material was stored and maintained free from terrestrial influences, including exposure to Earth's atmosphere. Several grains of interest were identified and further characterised to obtain quantitative information on the rare earth element (REE) content within said grains, following a reference-based and computed-tomography-assisted fundamental parameters quantification approach. Several orders of magnitude REE enrichments compared to the mean CI chondrite composition were found within grains that could be identified as apatite phase. Small enrichment of LREE was found for dolomite grains and slight enrichment or depletion for the general matrices within the Ryugu rock fragments A0055 and C0076, respectively. [ABSTRACT FROM AUTHOR]

An X-ray diffraction computed tomography data-collection strategy that allows, post experiment, a choice between temporal and spatial resolution is reported. This strategy enables time-resolved studies on comparatively short timescales, or alternatively allows for improved spatial resolution if the system under study, or components within it, appear to be unchanging. The application of the method for studying an Mn-Na-W/SiO2 fixed-bed reactor in situ is demonstrated. Additionally, the opportunities to improve the data-collection strategy further, enabling post-collection tuning between statistical, temporal and spatial resolutions, are discussed. In principle, the interlaced scanning approach can also be applied to other pencil-beam tomographic techniques, like X-ray fluorescence computed tomography, X-ray absorption fine structure computed tomography, pair distribution function computed tomography and tomographic scanning transmission X-ray microscopy. [ABSTRACT FROM AUTHOR]

This article reports the creation of tomographic reconstructions giving three-dimensional data on the distribution of various structural features for SAPO-34 zeolite catalyst beds used in the commercially important methanol to olefin conversion process. The data were processed using parametric Rietveld refinement to treat entire slices of the tomograph as single refined data sets, allowing extraction of real structural parameters from all voxels of the reconstruction. This has the advantage over more traditional methods of X-ray diffraction computed tomography using peak intensities, that the structural parameters are independent of the intensity, meaning that information can still be extracted from poor data sets: an example is shown where part of the sample was no longer in the beam during data collection. Reconstructions using several structural parameters are presented and the results compared. Analysis of the variation of the catalyst c axis (linked to the degree of deactivation in earlier work) shows small but significant three-dimensional variations in the degree of deactivation with patterns which depend on the silicon content of the catalyst. Average data for the tomographic slices compare well with the results of earlier operando two-dimensional reactor scanning experiments. [ABSTRACT FROM AUTHOR]

This paper reports a simple but effective filtering approach to deal with single-crystal artefacts in X-ray diffraction computed tomography (XRD-CT). In XRD-CT, large crystallites can produce spots on top of the powder diffraction rings, which, after azimuthal integration and tomographic reconstruction, lead to line/streak artefacts in the tomograms. In the simple approach presented here, the polar transform is taken of collected two-dimensional diffraction patterns followed by directional median/mean filtering prior to integration. Reconstruction of one-dimensional diffraction projection data sets treated in such a way leads to a very significant improvement in reconstructed image quality for systems that exhibit powder spottiness arising from large crystallites. This approach is not computationally heavy which is an important consideration with big data sets such as is the case with XRD-CT. The method should have application to two-dimensional X-ray diffraction data in general where such spottiness arises. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) is typically silent towards information on low loadings of precious metals on solid catalysts because of their finely dispersed nature. When combined with a concentration modulation approach, time-resolved high-energy XRD is able to provide the detailed redox dynamics of palladium nanoparticles with a diameter of 2 nm in 2 wt % Pd/CZ (CZ=ceria-zirconia), which is a difficult sample for extended X-ray absorption fine structure (EXAFS) measurements because of the cerium component. The temporal evolution of the Pd(111) and Ce(111) reflections together with surface information from synchronous diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements reveals that Ce maintains Pd oxidized in the CO pulse, whereas reduction is detected at the beginning of the O2 pulse. Oxygen is likely transferred from Pd to Ce3+ before the onset of Pd re-oxidation. In this context, adsorbed carbonates appear to be the rate-limiting species for re-oxidation. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) is typically silent towards information on low loadings of precious metals on solid catalysts because of their finely dispersed nature. When combined with a concentration modulation approach, time-resolved high-energy XRD is able to provide the detailed redox dynamics of palladium nanoparticles with a diameter of 2 nm in 2 wt % Pd/CZ (CZ=ceria-zirconia), which is a difficult sample for extended X-ray absorption fine structure (EXAFS) measurements because of the cerium component. The temporal evolution of the Pd(111) and Ce(111) reflections together with surface information from synchronous diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements reveals that Ce maintains Pd oxidized in the CO pulse, whereas reduction is detected at the beginning of the O2 pulse. Oxygen is likely transferred from Pd to Ce3+ before the onset of Pd re-oxidation. In this context, adsorbed carbonates appear to be the rate-limiting species for re-oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Computed X-ray diffraction tomography applied to shaped zeolite catalyst extrudates. • Operando monitoring of coking within a single extrudate during methanol conversion. • A strong radial gradient in the coke deposition and incomplete catalyst utilization is observed. • Operando data collection provide the basis for kinetic/diffusion simulation models. We have used operando X-ray diffraction computed tomography (XRD-CT) analysed by rigorous crystallographic methods to reveal the behaviour of a zeolite/alumina based catalyst extrudate in the methanol-to-hydrocarbon reaction under working conditions (T reaction = 440 °C; ambient total pressure; WHSV = 12 g MeOH g extrudate −1 h−1). By doing so, we demonstrate that it is possible to precisely monitor how the cylindrical extrudate is deactivated during the process by gradual filling with coke from the outer surface towards the core. The operando data thus collected are simulated by a model taking both the reaction kinetics and the diffusion within the extrudate into account, and this analysis provides the tools required for future optimization of the degree of utilization of the catalyst. Both the operando experiment and post mortem XRD-CT of fully deactivated extrudates from a test reactor show clearly that the core of the catalyst body, around 1/3 of its volume, remains completely untouched by the reaction, even when the reactor output indicates zero activity. [ABSTRACT FROM AUTHOR]

Synchrotron X-ray tomography enables the examination of the internal structure of materials at submicron spatial resolution and subsecond temporal resolution. Unavoidable experimental constraints can impose dose and time limits on the measurements, introducing noise in the reconstructed images. Convolutional neural networks (CNNs) have emerged as a powerful tool to remove noise from reconstructed images. However, their training typically requires collecting a dataset of paired noisy and high-quality measurements, which is a major obstacle to their use in practice. To circumvent this problem, methods for CNN-based denoising have recently been proposed that require no separate training data beyond the already available noisy reconstructions. Among these, the Noise2Inverse method is specifically designed for tomography and related inverse problems. To date, applications of Noise2Inverse have only taken into account 2D spatial information. In this paper, we expand the application of Noise2Inverse in space, time, and spectrum-like domains. This development enhances applications to static and dynamic micro-tomography as well as X-ray diffraction tomography. Results on real-world datasets establish that Noise2Inverse is capable of accurate denoising and enables a substantial reduction in acquisition time while maintaining image quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synchrotron X-ray diffraction computed tomography applied to three packed bed catalytic membrane reactors. • The solid-state evolution of catalysts and membranes is tracked under operating conditions. • A new crystal structure model of BaCo 0.4 Fe 0.4 Zr 0.2 O 3- δ (BCFZ) is suggested and used for the diffraction data analysis. Catalytic membrane reactors have the potential to render the process of oxidative coupling of methane economically viable. Here, the results from operando XRD-CT studies of three different catalytic membrane reactors, employing BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ (BCFZ) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) perovskite membranes with Mn-Na-W/SiO 2 and La-promoted Mn-Na-W/SiO 2 catalysts, are presented. It is shown that synchrotron X-ray tomographic diffraction imaging allows the extraction of spatially-resolved diffraction information from the interior of these working catalytic membrane reactors and makes it possible to capture the evolving solid-state chemistry of their components under various operating conditions (i.e. temperature and chemical environment). [ABSTRACT FROM AUTHOR]

Alloy melts can solidify into metallic glasses if cooled fast enough to avoid crystallization. Glass-forming ability (GFA), a measure of the ease of vitrification, is vital for the fundamental understanding of glass formation, and is also crucial for the application of metallic glasses. Previous studies of GFA mainly focused on the undercooled liquid phase, while the influence of the evolution of the stable melts on GFA is rarely addressed. Here we show that the Pd 42.5 Ni 42.5 P 15 glass-forming liquid, in which a first-order liquid-liquid transition (LLT) takes place at T LL = 1063 K high above its liquidus temperature, shows significantly different GFA when quenched from the temperature above or below T LL. Moreover, the pathway and kinetics of crystallization of the melt are strongly related to the kinetics of the LLT. Our work provides new insights into the vitrification process and the kinetics of crystallization, and contributes to designing more stable metallic glasses. Image, graphical abstract [ABSTRACT FROM AUTHOR]

While a detailed knowledge of the hierarchical structure and morphology of the extracellular matrix is considered crucial for understanding the physiological and mechanical properties of bone and cartilage, the orientation of collagen fibres and carbonated hydroxyapatite (HA) crystallites remains a debated topic. Conventional microscopy techniques for orientational imaging require destructive sample sectioning, which both precludes further studies of the intact sample and potentially changes the microstructure. In this work, we use X-ray diffraction tensor tomography to image non-destructively in 3D the HA orientation in a medial femoral condyle of a piglet. By exploiting the anisotropic HA diffraction signal, 3D maps showing systematic local variations of the HA crystallite orientation in the growing subchondral bone and in the adjacent mineralized growth cartilage are obtained. Orientation maps of HA crystallites over a large field of view (~ 3 × 3 × 3 mm3) close to the ossification (bone-growth) front are compared with high-resolution X-ray propagation phase-contrast computed tomography images. The HA crystallites are found to predominantly orient with their crystallite c-axis directed towards the ossification front. Distinct patterns of HA preferred orientation are found in the vicinity of cartilage canals protruding from the subchondral bone. The demonstrated ability of retrieving 3D orientation maps of bone-cartilage structures is expected to give a better understanding of the physiological properties of bones, including their propensity for bone-cartilage diseases. [ABSTRACT FROM AUTHOR]

• X-ray tomographic chemical imaging of working catalysts. • Improving the chemical stability of Mn-Na-W/SiO 2 catalyst with La. • Insight into the multiple roles of the La-promoter. • Capturing the state of the active catalysts. In this work, we present the results from multi-length-scale studies of a Mn-Na-W/SiO 2 and a La-promoted Mn-Na-W/SiO 2 catalyst during the oxidative coupling of methane reaction. The catalysts were investigated from the reactor level (mm scale) down to the single catalyst particle level (μm scale) with different synchrotron X-ray chemical computed tomography techniques (multi-modal chemical CT experiments). These operando spatially-resolved studies performed with XRD-CT (catalytic reactor) and multi-modal μ-XRF/XRD/absorption CT (single catalyst particle) revealed the multiple roles of the La promoter and how it provides the enhancement in catalyst performance. It is also shown that non-crystalline Mn species are part of the active catalyst component rather than crystalline Mn 2 O 3 /Mn 7 SiO 12 or MnWO 4. [ABSTRACT FROM AUTHOR]

ID15A is a newly refurbished beamline at the ESRF devoted to operando and time‐resolved diffraction and imaging, total scattering and diffraction computed tomography. The beamline is optimized for rapid alternation between the different techniques during a single operando experiment in order to collect complementary data on working systems. The high available energy (up to 120 keV) means that even bulky and highly absorbing systems may be studied. The beamline is equipped with optimized focusing optics and a photon‐counting CdTe pixel detector, allowing for both unprecedented data quality at high energy and for very rapid triggered experiments. A large choice of imaging detectors and ancillary probes and sample environments is also available. [ABSTRACT FROM AUTHOR]

We report the first cocrystal as an intermediate in a solid-state organic reaction wherein molecules of barbituric acid and vanillin assume a favorable orientation for the subsequent Knoevenagel condensation. [ABSTRACT FROM AUTHOR]

Mechanochemical milling of equimolar mixtures of salicylic acid with three hydroxy derivatives of pyridine provided three new phases. With 2-hydroxypyridine, which is in fact present as 2-pyridone, a discrete cocrystal supramolecular assembly is formed. 3-hydroxypyridine and salicylic acid formed a salt and an extended network of hydrogen bonds while the product of the reaction of 4-hydroxypyridine (present as 4- pyridone) and salicylic acid remained structurally uncharacterized. All three hydroxypyridines retain the tautomeric form as in their respective pure phases upon cocrystal formation. Where possible, reaction profiles have been extracted from in situ monitoring via Rietveld refinement to show direct product formation which could be well described using the first-order reaction rate law. [ABSTRACT FROM AUTHOR]

Residual stresses are considered to be the driving forces for the in-service failure of TBCs. The residual stress distribution through an APS TBC has been experimentally measured by high energy synchrotron X-ray diffraction (XRD) showing two distinct features. Firstly a discontinuity or ‘jump’ in the residual stress trend at a depth of approximately 100 μm from the interface. Secondly we observed a much larger stress gradient than that theoretically predicted. To understand these observations the measured residual stress was compared with analytical and finite element models based on the real 2D and 3D microstructure of the coating visualized by scanning electron microscopy (SEM) and high energy X-ray micro-computed tomography (μ-CT). The effect of the pores in the coating and the rumpled interface between the top coat and the bond coat on the residual stress distribution was studied by image based modelling. It was found that the pores did not have an obvious effect on the overall residual stress distribution. The rumpled interface however was primarily responsible for the jump in the trend. This feature was observed to be located at a depth of approximately 120 μm from the surface with an overall magnitude of approximately 200 MPa. The relaxation of the coating upon in-plane compression was investigated by mechanical testing coupled with DIC. These results are in good agreement with the much larger gradients in the measured residual stress distribution. [ABSTRACT FROM AUTHOR]

Linear parabolic diamond refractive lenses are presented, designed to withstand high thermal and radiation loads coming from upgraded accelerator X-ray sources. Lenses were manufactured by picosecond laser treatment of a high-quality single-crystal synthetic diamond. Twelve lenses with radius of curvature at parabola apex R = 200 µm, geometrical aperture A = 900 µm and length L = 1.5 mm were stacked as a compound refractive lens and tested at the ESRF ID06 beamline. A focal spot of size 2.2 µm and a gain of 20 were measured at 8 keV. The lens profile and surface quality were estimated by grating interferometry and X-ray radiography. In addition, the influence of X-ray glitches on the focusing properties of the compound refractive lens were studied. [ABSTRACT FROM AUTHOR]

In the microelectronics industry the flip-chip (FC) technology is broadly used to enhance the packaging density. However, the small size and the unique geometry of the FC solder joints induce the electromigration (EM) reliability issue. In this study, a pair of lead-free solder joints (SAC1205) was EM tested by a current of 7.5 × 10 3 A/cm 2 . During the tests, X-ray laminography was applied to observe the microstructure evolution in-situ . Laminography enables the non-destructive observation of the bump microstructure and allows for a quantitative three-dimensional (3D) analysis. After EM testing for 650 h, a new EM failure mechanism was found, differing from the two well-known models, the pancake void propagation and the under-bump-metallization dissolution. Here, a few pre-existing small voids grew and simultaneously many new voids formed and grew over the entire EM testing period. Most of the nucleating voids were distributed in the current crowding region, a few also located in the low-current-density region. As the testing time increased, voids increasingly coalesced with each other, forming a porous network which occupied a large part of the interface area and caused the EM failure. A finite-element (FE) method was then applied to analyze the interplay between the microstructure evolution and current density redistribution. A series of 3D FE models was built based on the laminography images for the different testing stages. The current density distribution from the FE analysis indicates that the formation of discrete voids did not affect the global current density distribution until a major coalescence of the voids occurred. The relieving of the global current crowding in the pancake void model was not found in this new EM failure mechanism. It was the local current crowding around individual void found in the new mechanism that is held responsible for the EM retardation. [ABSTRACT FROM AUTHOR]

Semiconducting indium sulfide (In2S3) has recently attracted considerable attention as a buffer material in the field of thin film photovoltaics. Compared with this growing interest, however, detailed characterizations of the crystal structure of this material are rather scarce and controversial. In order to close this gap, we have carried out a reinvestigation of the crystal structure of this material with an in situ X-ray diffraction study as a function of temperature using monochromatic synchrotron radiation. For the purpose of this study, high quality polycrystalline In2S3 material with nominally stoichiometric composition was synthesized at high temperatures. We found three modifications of In2S3 in the temperature range between 300 and 1300 K, with structural phase transitions at temperatures of 717 K and above 1049 K. By Rietveld refinement we extracted the crystal structure data and the temperature coefficients of the lattice constants for all three phases, including a high-temperature trigonal γ-In2S3 modification. [ABSTRACT FROM AUTHOR]

Tracking the dynamic morphology of active materials during operation of lithium batteries is essential for identifying causes of performance loss. Digital volume correlation (DVC) is applied to high‐speed operando synchrotron X‐ray computed tomography of a commercial Li/MnO2 primary battery during discharge. Real‐time electrode material displacement is captured in 3D allowing degradation mechanisms such as delamination of the electrode from the current collector and electrode crack formation to be identified. Continuum DVC of consecutive images during discharge is used to quantify local displacements and strains in 3D throughout discharge, facilitating tracking of the progression of swelling due to lithiation within the electrode material in a commercial, spiral‐wound battery during normal operation. Displacement of the rigid current collector and cell materials contribute to severe electrode detachment and crack formation during discharge, which is monitored by a separate DVC approach. Use of time‐lapse X‐ray computed tomography coupled with DVC is thus demonstrated as an effective diagnostic technique to identify causes of performance loss within commercial lithium batteries; this novel approach is expected to guide the development of more effective commercial cell designs. [ABSTRACT FROM AUTHOR]

In recent times there has been much progress in the imaging of functional materials under the process conditions typically used in a real industrial process. In this article the progress made in diffraction imaging in terms of both acquisition methodology (i.e. using white beam or monochromatic sources, tomography or imaging) and their application to tackle real problems in the field of industrial heterogeneous catalysis are discussed. The exemplar studies also illustrate the recent developments in sample environment that, when considered alongside the developments in diffraction imaging, allows us to propose that the information extracted from these studies are far more inclusive (conclusive?) in terms of the type (including physicochemical insight) and amount of information they yield. With the current and protracted developments in source, infrastructure, detector and software technologies it is not unreasonable to assume that such approaches will supersede the more traditional ‘single point’ in situ methods for studying industrial processes. Diffraction imaging methods in their various guises may also eventually replace the established technique of X-ray Absorption μ-CT currently applied intensively across research and diagnostic fields including biomaterials, geology, environmental science, palaeontology, cultural heritage and health. [ABSTRACT FROM AUTHOR]

In-situ synchrotron x-ray experiments have been used to follow the evolution of the diffraction peaks for crystalline dendrites embedded in a bulk metallic glass matrix subjected to a compressive loading-unloading cycle. We observe irreversible diffraction-peak splitting even though the load does not go beyond half of the bulk yield strength. The chemical analysis coupled with the transmission electron microscopy mapping suggests that the observed peak splitting originates from the chemical heterogeneity between the core (major peak) and the stiffer shell (minor peak) of the dendrites. A molecular dynamics model has been developed to compare the hkl-dependent microyielding of the bulk metallic-glass matrix composite. The complementary diffraction measurements and the simulation results suggest that the interface, as Maxwell damper, between the amorphous matrix and the (211) crystalline planes relax under prolonged load that causes a delay in the reload curve which ultimately catches up with the original path. [ABSTRACT FROM AUTHOR]

Different solutions have been proposed over the years to optimize control of the temperature and atmosphere over a catalyst in order to reach an ideal reactor behavior. Here, a new innovative solution which aims to minimize temperature gradients along the catalyst bed is demonstrated. This was attained by focusing the infrared radiation generated from the heating elements onto the catalyst bed with the aid of an aluminium shield. This method yields a ∼0.13 K mm−1 axial temperature gradient ranging from 960 to 1173 K. With the selection of appropriate capillaries, pressures of 20 bar (2 MPa) can be attained. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The evolution of time-resolved experiments, covering a multipurpose surface and bulk characterization of catalytic solids, during their preparation process and under reaction conditions, is presented. Particular emphasis is given to recent studies that attempt to unveil contemporary unresolved questions concerning the control of physicochemical properties of nanosolids, as well as the evolution of such solid materials under reactive atmospheres. To reach this goal, representative in situ and in operando works, using either modern (mostly synchrotron radiation based) approaches or multi-technique methods (mainly, although not exclusively, X-ray-vibrational coupling), and considering experiments in liquid and gas phase, as well as with amorphous, nanocrystalline and surface-deposited materials, are reviewed. [ABSTRACT FROM AUTHOR]

Ultrafast synchrotron microtomography has been used to study in situ and in real time the initial stages of silicate glass melt formation from crystalline granular raw materials. Significant and unexpected rearrangements of grains occur below the nominal eutectic temperature, and several drastically different solid-state reactions are observed to take place at different types of intergranular contacts. These reactions have a profound influence on the formation and composition of the liquids produced, and control the formation of heterogeneities. [ABSTRACT FROM AUTHOR]

A combination of time-resolved X-ray absorption spectroscopy (XAS), hard X-ray diffraction (HXRD), diffuse reflectance infrared spectroscopy (DRIFTS), and mass spectrometry (MS) reveals a series of size-dependent phenomena at Pd nanoparticles upon CO/(NO+O2) cycling conditions. The multitechnique approach and analysis show that such size-dependent phenomena are critical for understanding Pd CO elimination behavior and, particularly, that different Pd(I) and Pd(0) centers act as active species for a size estimated by XAS to be, respectively, below and above ca. 3 nm. The relative catalytic performance of these two noble metal species indicates the intrinsic higher activity of the Pd(I) species. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the working principles of heterogeneous catalysts represents one of the great challenges in the field of materials science today. Ex situ bulk and surface science techniques provide information on such systems; however it is difficult to know whether any observed change in the physicochemical state of the catalyst would occur under the real working conditions. To counter this operando gap, the last decade has witnessed research efforts pushing towards more operando-like experimental setups to investigate ‘catalysis in action’. The advances in this field have been considerable so that it is now feasible to observe catalytic materials using a variety of techniques (sometimes combined into a single experiment) under conditions approaching those used for commercial operation. There still remain, however, some key differences between the conditions under which the experiments and the measurements are performed and with those required to fully understand a catalyst material in an industrial setting. In this paper we aim to show how multiple high energy techniques can be employed to further close the operando gap and meet the relevant criteria of replicating industrially relevant conditions and gleaning useful high quality data, whilst minimizing sample effects. For this purpose, a new high energy source experimental setup is described. We present results from high energy X-ray experiments on a simple model parent oxide, molybdenum oxide (MoO3) used for the selective oxidation of methanol as well as a new characterization study on the more complex iron molybdate (Fe2(MoO4)3) catalyst. The advantages and limitations of high energy X-ray experiments will be discussed. [ABSTRACT FROM AUTHOR]

Abstract: The behaviour of Pd/Al2O3 supported catalysts with metal loading in the 0.5–4wt.% interval has been examined during cycling CO/NO conditions in an attempt to interpret the size-dependence of the metal chemical activity within a dynamic redox situation. To this end, a synchronous, multitechnique approach using X-ray absorption (XAS) or hard X-ray diffraction (HXRD) in tandem with diffuse reflectance infrared spectroscopy (DRIFTS) and mass spectrometry (MS) was used to establish the size-dependence of chemically significant steps in formation of N2 and CO2. During cycling, EXAFS and HXRD reveal the existence of a reversible Pd morphology and phase change (PdC x formation and removal) phenomena in response to the gas atmosphere reducing/oxidizing nature. This is observed for Pd particles having dispersion values going from ca. 1–0.4. Using EXAFS Pd–Pd coordination numbers, we dynamically normalized the DRIFTS and MS signals obtained during cycling conditions and find that metal size/phase-effects appear of importance in CO2 formation but can be essentially neglected in N2 formation. Such (size-dependent) metal behaviour appears far from expectations coming from studies using non-cycling gas mixtures. The chemical relevance of NO, CO activation, dissociation and coupling steps are discussed in relation to the product formation and their size-dependence or independence. [Copyright &y& Elsevier]

This work analyses the microstructure changes of various copper-based powder systems during sintering from 3D images provided by in situ synchrotron microtomography. The investigated systems include a copper powder with a wide particle size distribution of 0-63 µm poured into a quartz capillary, a pre-sintered copper compact with artificially created large pores and a mixture of copper and alumina particles. The experiments were carried out at the European Synchrotron in Grenoble, France. Powders were sintered up to 1060°C under reducing atmosphere in a furnace located between the X-ray source and the detector. During each experiment, 3D images were taken at various times of the thermal cycle. We have obtained images with a resolution of 1.5 µm and the time of acquisition of every image was ∼1 min. Quantitative analysis of these images allowed the changes of various important parameters to be followed. Such parameters characterise the sintering process at the particle length scale: interparticle coordination, pore size distribution and particle centre-to-centre distance. Moreover, by tracking the displacement of each particle centre and comparing it to the displacement predicted by classical mean field assumption, we have been able to assess the magnitude of particle rearrangement occurring during sintering. From these data, the sintering behaviour of heterogeneous powder systems is discussed with particular emphasis of collective particle phenomena. [ABSTRACT FROM AUTHOR]

Collective particle behavior such as interparticle coordination and particle rearrangement plays a significant role in the sintering of heterogeneous powder systems. Those phenomena have been investigated by in situ X-ray microtomography and discrete element simulation (DEM). In situ 3D images of sintering copper-based systems have been obtained at the European Synchrotron Research Facilities. The sintered systems comprise a dense packing of atomized copper powder with a size range of 0–63 μm and the same powder including artificial pores. Quantitative analysis of these images provided valuable data on local strain, coordination number, and particle movement. The sintering of the same systems has been simulated with the discrete element code dp3D. From this set of information, the importance of collective behavior on densification and microstructural evolution is assessed and the relevance of DEM to describe it is discussed. [ABSTRACT FROM AUTHOR]