Imaging hydrogen interactions with materials at the nanoscale: SIMS-based correlative microscopy

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In-situ isotopic analysis at nanoscale using parallel ion electron spectrometry: a powerful new paradigm for correlative microscopy

Isotopic analysis is of paramount importance across the entire gamut of scientific research. To advance the frontiers of knowledge, a technique for nanoscale isotopic analysis is indispensable. Secondary Ion Mass Spectrometry (SIMS) is a well-established technique for analyzing isotopes, but its spatial-resolution is fundamentally limited. Transmission Electron Microscopy (TEM) is a well-known method for high-resolution imaging down to the atomic scale. However, isotopic analysis in TEM is not possible. Here, we introduce a powerful new paradigm for in-situ correlative microscopy called the Parallel Ion Electron Spectrometry by synergizing SIMS with TEM. We demonstrate this technique by distinguishing lithium carbonate nanoparticles according to the isotopic label of lithium, viz. 6Li and 7Li and imaging them at high-resolution by TEM, adding a new dimension to correlative microscopy

A FIB-SEM Based Correlative Methodology for X-Ray Nanotomography and Secondary Ion Mass Spectrometry: An Application Example in Lithium Batteries Research

Correlative microscopy approaches are attracting considerable interest in several research fields such as materials and battery research. Recent developments regarding X-ray computer tomography have made this technique available in a compact module for scanning electron microscopes (SEMs). Nano-computed tomography (nanoCT) allows morphological analysis of samples in a nondestructive way and to generate 2D and 3D overviews. However, morphological analysis alone is not sufficient for advanced studies, and to draw conclusions beyond morphology, chemical analysis is needed. While conventional SEM-based chemical analysis techniques such as energy-dispersive X-ray spectroscopy (EDS) are adequate in many cases, they are not well suited for the analysis of trace elements and low-Z elements such as hydrogen or lithium. Furthermore, the large information depth in typical SEM-EDS imaging conditions limits the lateral resolution to micrometer length scales. In contrast, secondary ion mass spectrometry (SIMS) can perform elemental mapping with good surface sensitivity, nanoscale lateral resolution, and the possibility to analyze even low-Z elements and isotopes. In this study, we demonstrate the feasibility and compatibility of a novel FIB-SEM-based correlative nanoCT-SIMS imaging approach to correlate morphological and chemical data of the exact same sample volume, using a cathode material of a commercial lithium battery as an example

4D Surface Reconstruction of Micron-Sized Organic Calcite for the Characterization of Chemical Heterogeneity of Chalk Surfaces

Seawater injection into chalk reservoirs is a method for improved oil recovery (IOR) at the Norwegian Continental Shelf (NCS). During the injection of fluids for IOR, complex physicochemical interactions between the injected fluid and the reactive rock surface will take place, such as compaction and alterations of rock properties (e.g., porosity, permeability, wettability). The distribution of noncarbonate mineral phases in the reservoir and on the surface of the chalk will dictate wettability properties. Yet, the identification and quantification of nanometer-sized mineral phases on calcite surfaces have been challenging due to insufficient spatial resolution and sensitivity of the analytical methods used. On-shore chalk was used in this study. Helium ion microscopy (HIM) combined with in situ secondary ion mass spectrometry (SIMS) was used to produce secondary electron images for mapping surface morphology and topography correlated with chemical maps from SIMS. First, a 3D surface model was created from a series of secondary electron images acquired from different perspectives around the coccolith. A chemical image obtained by SIMS was developed on the same region of interest and projected onto the 3D surface model to create a 4D surface reconstruction (3D+1 concept). This includes surface chemistry information on sub-micron-sized noncarbonate phases on calcite grains. The surface distribution of noncarbonate phases added up to a minimum of 6.3%, where no 40Ca had been detected. Moreover, 39.8% of the entire area is characterized by 40Ca and 27Al plus 28Si. Compared with 5 wt % noncarbonate phases identified by whole-rock geochemistry, we identify at least 200–300% higher noncarbonate phase abundance than expected based on bulk geochemistry. This has a significant implication for the modeling of mineral surface charges, the major criteria for wettability calculations. Therefore, HIM-SIMS studies allow nanoscale mapping and mineral phase identification, which will enhance the knowledge of fluid–rock interactions for purposes related to IOR, carbon capture, and storage as well as for hydrogen storage.publishedVersio

Quantitative nanoscale imaging using transmission He ion channelling contrast: Proof-of-concept and application to study isolated crystalline defects

A newly developed microscope prototype, namely npSCOPE, consisting of a Gas Field Ion Source (GFIS) column and a position sensitive Delay-line Detector (DLD) was used to perform Scanning Transmission Ion Microscopy (STIM) using keV He+ ions. One experiment used 25 keV ions and a second experiment used 30 keV ions. STIM imaging of a 50 nm thick free-standing gold membrane exhibited excellent contrast due to ion channelling and revealed rich microstructural features including isolated nanoscale twin bands which matched well with the contrast in the conventional ion-induced Secondary Electron (SE) imaging mode. Transmission Kikuchi Diffraction (TKD) and Backscattered Electron (BSE) imaging were performed on the same areas to correlate and confirm the microstructural features observed in STIM. Monte Carlo simulations of the ion and electron trajectories were performed with parameters similar to the experimental conditions to derive insights related to beam broadening and its effect in the degradation of transmission image resolution. For the experimental conditions used, STIM imaging showed a lateral resolution close to30 nm. Dark twin bands in bright grains as well as bright twin bands in dark grains were observed in STIM. Some of the twin bands were invisible in STIM. For the specific experimental conditions used, the ion transmission efficiency across a particular twin band was found to decrease by a factor of 2.8. Surprisingly, some grains showed contrast reversal when the Field of View (FOV) was changed indicating the sensitivity of the channelling contrast to even small changes in illumination conditions. These observations are discussed using ion channelling conditions and crystallographic orientations of the grains and twin bands. This study demonstrates for the first time the potential of STIM imaging using keV He+ ions to quantitatively investigate channelling in nanoscale structures including isolated crystalline defects

High-Resolution Topographic and Chemical Surface Imaging of Chalk for Oil Recovery Improvement Applications

Chalk is a very fine-grained carbonate and can accommodate high porosity which is a key characteristic for high-quality hydrocarbon reservoirs. A standard procedure within Improved Oil Recovery (IOR) is seawater-injection which repressurizes the reservoir pore pressure. Long-term seawater-injection will influence mineralogical processes as dissolution and precipitation of secondary minerals. These secondary minerals (<1 micrometer) precipitate during flooding experiments mimicking reservoir conditions. Due to their small sizes, analysis from traditional scanning electron microscopy combined with energy dispersive X-ray spectroscopy is not conclusive because of insufficient spatial resolution and detection limit. Therefore, chalk was analyzed with high-resolution imaging by helium ion microscopy (HIM) combined with secondary ion mass spectrometry (SIMS) for the first time. Our aim was to identify mineral phases at sub-micrometer scale and identify locations of brine–rock interactions. In addition, we wanted to test if current understanding of these alteration processes can be improved with the combination of complementary imaging techniques and give new insights to IOR. The HIM-SIMS imaging revealed well-defined crystal boundaries and provided images of excellent lateral resolution, allowing for identification of specific mineral phases. Using this new methodology, we developed chemical identification of clay minerals and could define their exact location on micron-sized coccolith grains. This shows that it is essential to study mineralogical processes at nanometer scale in general, specifically in the research field of applied petroleum geology within IOR.publishedVersio

Quantification of hydrogen in nanostructured hydrogenated passivating contacts for silicon photovoltaics combining SIMS-APT-TEM : A multiscale correlative approach

Multiscale characterization of the hydrogenation process of silicon solar cell contacts based on c-Si/SiOx/nc-SiCx(p) has been performed by combining dynamic secondary ion mass-spectrometry (D-SIMS), atom probe tomography (APT), and transmission electron microscopy (TEM). These contacts are formed by high-temperature firing, which triggers the crystallization of SiCx, followed by a hydrogenation process to passivate remaining interfacial defects. Due to the difficulty of characterizing hydrogen at the nm-scale, the exact hydrogenation mechanisms have remained elusive. Using a correlative TEM-SIMS-APT analysis, we are able to locate hydrogen trap sites and quantify the hydrogen content. Deuterium (D), a heavier isotope of hydrogen, is used to distinguish hydrogen introduced during hydrogenation from its background signal. D-SIMS is used, due to its high sensitivity, to get an accurate deuterium-to-hydrogen ratio, which is then used to correct deuterium profiles extracted from APT reconstructions. This new methodology to quantify the concentration of trapped hydrogen in nm-scale structures sheds new insights on hydrogen distribution in technologically important photovoltaic materials

Patterning enhanced tetragonality in BiFeO3 thin films with effective negative pressure by helium implantation

Helium implantation in epitaxial thin films is a way to control the out-of-plane deformation independentlyfrom the in-plane strain controlled by epitaxy. In particular, implantation by means of a helium microscopeallows for local implantation and patterning down to the nanometer resolution, which is of interest for deviceapplications. We present here a study of bismuth ferrite (BiFeO3) films where strain was patterned locally byhelium implantation. Our combined Raman, x-ray diffraction, and transmission electron microscopy (TEM)study shows that the implantation causes an elongation of the BiFeO3unit cell and ultimately a transition towardsthe so-called supertetragonal polymorph via states with mixed phases. In addition, TEM reveals the onset ofamorphization at a threshold dose that does not seem to impede the overall increase in tetragonality. The phasetransition from the R-like to T-like BiFeO3appears as first-order in character, with regions of phase coexistenceand abrupt changes in lattice parameters

ASIME 2018 White Paper. In-Space Utilisation of Asteroids: Asteroid Composition -- Answers to Questions from the Asteroid Miners

In keeping with the Luxembourg government's initiative to support the future use of space resources, ASIME 2018 was held in Belval, Luxembourg on April 16-17, 2018. The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to focus on asteroid composition for advancing the asteroid in-space resource utilisation domain. What do we know about asteroid composition from remote-sensing observations? What are the potential caveats in the interpretation of Earth-based spectral observations? What are the next steps to improve our knowledge on asteroid composition by means of ground-based and space-based observations and asteroid rendez-vous and sample return missions? How can asteroid mining companies use this knowledge? ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in the context of the engineering needs of space missions with in-space asteroid utilisation. The 21 Questions from the asteroid mining companies were sorted into the four asteroid science themes: 1) Potential Targets, 2) Asteroid-Meteorite Links, 3) In-Situ Measurements and 4) Laboratory Measurements. The Answers to those Questions were provided by the scientists with their conference presentations and collected by A. Graps or edited directly into an open-access collaborative Google document or inserted by A. Graps using additional reference materials. During the ASIME 2018, first day and second day Wrap-Ups, the answers to the questions were discussed further. New readers to the asteroid mining topic may find the Conversation boxes and the Mission Design discussions especially interesting.Comment: Outcome from the ASIME 2018: Asteroid Intersections with Mine Engineering, Luxembourg. April 16-17, 2018. 65 Pages. arXiv admin note: substantial text overlap with arXiv:1612.0070