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Abstract: Understanding the degradation of large format lithium-ion pouch cells – critical for electric vehicle applications – is vital to extend their lifetime and allow potential second-life application. Here, the impact on capacity fade and material degradation in two end-of-life cells, which were additionally subjected to accelerated aging to mimic extended use in second-life applications, were examined using powder synchrotron X-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy, complemented by detailed post mortem analyses. The dominant mechanism of capacity loss under these conditions was found to be lithium inventory depletion, driven by processes such as electrolyte decomposition, lithium plating and solid electrolyte interphase growth. Structural changes in the graphite anode, including amorphization and reduced active material, were more pronounced under severe overcharging conditions. The blended cathode showed lithium inventory loss in both phases, but 92–94% capacity recovery was observed on subsequent cycling in half cells vs Li, illustrating its robustness, with little structural degradation observed. The finding that electrolyte degradation/loss in these cells was a more critical contributor to cell degradation toward the knee-point than electrode active material degradation/loss indicates that increasing – or replenishing – the electrolyte content could be a strategy to extend the usable life of such cells.

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Abstract: Non-destructive testing using X-ray computer tomography (XCT) has been used to assess the applicability of visualising ceramic kernels held within a dissimilar ceramic matrix. Simulations were performed to ascertain the feasibility of CT scans of such samples, and optimise the scanning parameters offline. Corresponding experiments were carried out to assess the defects in the structure that exist as a result of manufacturing methods in zirconium diboride (ZrB2) kernels held within a zirconium dioxide (ZrO2) matrix material. Ceramic–ceramic matrix composites are garnering a great deal of interest in a number of applications, including as nuclear fuels for high temperature gas reactors and the methodology presented has potential to be of use in assessing the position and state of pellets incorporated into a ceramic matrix, whilst being able to detect features such as cracks, porosity and interfaces between kernels and the matrix. Computer modelling of the composites supports the experimental observations and has been used to assess the plausibility of assessing a higher density of kernels held within a ceramic matrix that will support ongoing work, whilst highlighting a valid method for periodical assessment of fuel manufacturing processes.

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Abstract: Single crystal Ni-base superalloys, like many materials containing an A1 structured phase, demonstrate additional forbidden reflections in diffraction experiments. These additional reflections are most commonly attributed to the presence of chemical short-range order, or to thin foil effects in transmission electron microscopy. In this study, transmission electron diffraction and synchrotron X-ray diffraction were used to interrogate the deformation mechanics in a single crystal Ni-base superalloy at room temperature. Additional reflections were observed around those from the A1 phase in both diffraction experiments, arising from relrods along . These relrods were linked to the formation of extensive intrinsic stacking faults (ISFs) within the A1 phase, giving rise to local disorder and a relaxation of the Bragg condition. This study represents the first use of single crystal X-ray diffraction to characterise forbidden reflections in A1 structures from bulk specimens, thereby discounting thin foil effects completely.

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Abstract: A challenge in sample return missions to restricted bodies such as Mars, Europa, and Enceladus is enabling mineralogical and geochemical analyses whilst maintaining cleanliness and containment. Notably, due to the potential for back-contamination of Earth from possible extant life on these bodies, strict contamination control measures must be taken for the purposes of planetary protection [1]. These measures restrict how analyses can be performed on the samples until they have been sterilised or judged safe. As the first step of scientific analysis for Mars Sample Return (MSR), for example, sealed samples would undergo a set of measurements called Pre-Basic Characterisation, or Pre-BC [2]. These data would be used to inform tube opening and decide experimental plans for subsequent multi-instrument analyses. Pre-BC includes X-ray CT and magnetic measurements but X-ray Diffraction (XRD) for identification and quantification of crystalline mineral phases is currently only planned for a later phase, due to the need for sample powdering to achieve sufficient diffraction signal using a conventional laboratory diffractometer.XRD using a synchrotron source enables sampling of sealed MSR sample tubes, but tubes must be kept in containment throughout transport and measurements. We have developed a prototype container at Space Park Leicester that can be used to take unopened drill tubes in a Sample Receiving Facility to a synchrotron beamline such as Diamond Light Source's I12 and perform XRD analysis whilst maintaining containment.Figure 1: MSR sample tube container for synchrotron XRD.MethodThe sample container used stainless steel construction in accordance with the permissible materials list for MSR samples. Remotely operated, low-offgassing motorised stages were used to position the sample tube and rotate it for spatial averaging. The windows were made out of fused silica, with a 30 mm diameter, 1 mm thick inlet window, and 100 mm diameter, 2 mm thick outlet.Synchrotron powder XRD measurements were taken at the I12-JEEP beamline at Diamond Light Source. The diffraction methodology was similar to our previous study [3] at I12 in which a basaltic sediment from Þórisjökull, Iceland collected as an MSR analogue through the SAND-E program [4] in just a Ti sample tube analogue was analysed as a feasibility test. The only differences were a 56.59 keV X-ray energy and a 1224.7 mm sample-to-detector distance. Four samples were measured: a solid basalt core from Skye, UK; an Old Red Sandstone core from Pembrokeshire, UK; the Icelandic regolith analogue mentioned previously; and mudstone fragments from Watchet, UK. The last two are official Jezero Crater Mars analogues. Sample analogues inside sample tubes were placed inside the container and diffraction measurements were performed through the windows. An empty tube was also measured as reference.Semi-quantitative analysis was used to identify the mineral phases present and roughly estimate their quantity, shown for the Icelandic sediment in Fig. 2. Diffraction patterns had the window and tube background subtracted after intensity scaling to enable this analysis as in Adam et al. [3], though this method is imperfect. Rietveld refinement is in progress for more accurate phase quantification.ResultsThe expected three constituent minerals, plagioclase, pyroxene, olivine, could still be identified, though with differences in atomic site occupancy for two of the phases (andesine, diopside, and larnite compared to the expected anorthite, diopside, and forsterite). The Figure of Merit of the phase matches was reduced: from 0.792, 0.783, and 0.764 for plagioclase, pyroxene, and olivine respectively, to 0.710, 0.670, and 0.705. Estimated quantity also changed from 42.3%, 34.5% and 23.2%, to 34.5%, 25.9% and 39.6%, respectively, though precise quantification is not expected from this semi-quantitative approach and will come from Rietveld refinement.

Open Access

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Abstract: The preservation of archaeological bone is of great importance for both archaeological and conservation science studies. Traditional methods of preservation assessment, such as attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), are minimally invasive and destructive. Neutron and X-ray tomography offer a totally non-invasive novel analysis method for the state of preservation of archaeological bones. Seven archaeological animal bones were selected for analysis based on animal maturity, species, visual factors, and ATR-FTIR analysis results. Archaeological bone is a hierarchical composite material constructed from both organic and mineral components; therefore, neutron tomography and synchrotron X-ray tomography have been combined in this novel approach to assess the state of preservation of animal archaeological bone. The neutron data demonstrated that the organic distribution along the diaphysis of archaeological bones varied significantly both within bones and between different animal bones. There is minimal consistency between the samples, emphasizing the inhomogeneity in archaeological bone collections. X-ray tomography revealed unseen physical details, including cracks and substantial damage. The collection of this information via non-invasive methods is highly valuable for cultural heritage, providing a deeper understanding of the observed inhomogeneity in ATR-FTIR analysis data and revealing obscured physical details.