Advanced X-ray techniques to study the alteration of pigments in paintings

In situ X-ray absorption and diffraction studies of carbon coated LiFe 1/4Mn 1/4Co 1/4Ni 1/4PO 4 cathode during first charge

The aim of this work is to study the structural phase of (1-x)Bi0.5(Na0.74K0.16Li0.10)0.5TiO3–xBaZr0.05Ti0.95O3 ((1-x)BNKLT-xBZT) ceramics with various x content between 0.025 and 0.150 mol% synthesized via the combustion method. The X-ray diffraction (XRD), Raman spectroscopy and X-ray absorption spectroscopy (XAS), including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), were used to investigate the structural phases of all samples. The XRD pattern and Raman spectra revealed coexisting phases of rhombohedral (R) and tetragonal (T) in all compositions. As the BZT content increased, the phase formation in these samples exhibited higher tetragonality. The quantity of each phase in (1-x)BNKLT-xBZT ceramics can be determined by the XAS technique with Ti K-edge measurements. Increasing the BZT content from 0 to 0.15 mol% caused the R phase to suddenly deceased from 60.9% to 20% while the T phase rapidly increased from 39.1% to 80%. The phase of the structural was determined by several alternative strategies including XRD, Raman and XAS techniques.

Rechargeable battery research often involves improving electrodes to electrolyte materials with new chemistry with the end goals to lower cost, extend cycle life, higher energy densities and better safety. Advancements in battery and fuel cell research require the understanding of the complex interplay of several components and factors in a battery ecosystem. It calls for an integrated and multimodality approach involving several new analytical techniques which have to be capable of probing the batteries electrochemistry, structures and composition at different length and time scales, several of which have to be performed non destructively (ex-situ, in situ and in operando). Because of the need to study these in operando or at higher resolution or sensitivity, conventional lab based x-ray techniques are often inadequate. Most of this research is currently performed through synchrotron X-ray techniques. These include: X-ray Absorption Spectroscopy (XAS) to probe changes in oxidation states, bond lengths and coordination numbers of electrochemistry during charge-discharge cycles. XAS comprise XANES (X-ray absorption near edge spectroscopy) & EXAFS (Extended X-ray Absorption Fine Structure). They provide information on element-specific changes in oxidation state and local atomic structure. Such microscopic descriptors are crucial for elucidating charge transfer and structural changes associated with bonding or site mixing, two key factors in evaluating state of charge and modes of cell failure or catalytic efficiency. Another major technique is synchrotron X-ray Imaging at multiple lengthscales, from micrometers to 10s of nanometers through 3D X-ray Microscopy (XRM) to determine structural changes and degradation over time of the complex system, from the electrodes, separators, current collectors to binders. Trace level elemental composition at the ppm or sub-ppm level can be studied through high sensitivity synchrotron X-ray fluorescence spectroscopy (s-XRF)- to track the migration of metallic ions from cathode to anode during charge-discharge cycle or to investigate cross contamination during manufacturing.Unfortunately, many of these X-ray techniques such as XAS has to be performed almost exclusively at synchrotron X-ray light sources, where beamtime is infrequent and experiment time-frames are limited. As a consequence, high level battery, fuel cell or catalyst research in many research institutions have been largely curtailed. In this talk, we will discuss the advancements made in high flux, tunable lab x-ray sources and high efficiency optics for enabling novel synchrotron-equivalent XAS, XRM and XRF techniques in the laboratory. Breakthrough correlative applications through these suite of tools in the field of battery research and catalysts are now feasible in your own laboratory 24/7, without the constraint of limited access nor the research continuity challenges at synchrotron beamlines. Measurements results (including in operando) will be illustrated for conventional NMC batteries to novel solid-state lithium air batteries and next generation battery materials.

Development and recent progress of a depth-resolved X-ray absorption spectroscopy (XAS) technique are presented, together with future prospects. The technique has been developed by controlling the probing depth of the electron-yield XAS data, which depends on the electron emission angle. This novel technique enables us to achieve depth profiling of the magnetic structure of thin films with a sub-nm depth resolution by using X-ray magnetic circular dichroism (XMCD) in X-ray absorption, which provides quantitative information on the element-specific spin and orbital magnetic moments. The chemical state and electronic structure at the surface and interface are also investigated by depth-resolved XAS analysis. As for future prospects, a three-dimensional micro XAS technique is being developed by combining an X-ray microbeam with depth-resolved XAS. Moreover, it is expected to manipulate magnetic anisotropy by using element-specific and depth-resolved magnetic anisotropy energies obtained from the depth-resolved XMCD to design thin films and multilayers with proper elements and proper thicknesses. The observation of the spin dynamics at the interface will be also possible in future by adopting the pump-probe method.

The structure of the Zr atomic environment in a CaO–ZrO2–SiO2glass ceramic as a function of thermal treatments has been studied, combining X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) and anomalous XRD (a-XRD) techniques. The analysis of XRD patterns demonstrates that the devitrification process proceeds through the partial segregation of Zr-depleted phases (wollastonite-like) and Zr-rich phases (Zr oxides). The XAS and a-XRD measurements at the ZrK-edge have been exploited in order to obtain a closer insight into the atomic structure around the Zr atoms. In the as-quenched glass the Zr atom is sixfold coordinated to O atoms in an amorphous environment rich in Ca and Si. Thermal treatment firstly (T= 1273–1323 K) causes partial segregation of Zr in the form of an oxide with a tetragonal zirconia (t-ZrO2) crystalline structure. Raising the temperature (T= 1373 K) causes the formation of ZrO2crystallites in the monoclinic crystallographic phase (baddeleyite, m-ZrO2). Analysis of the XAS data shows that a considerable amount of Zr remains in an amorphous calcium silicate phase.

Unveiling scale differences in the two-phase transformation of [formula omitted][formula omitted][formula omitted] via operando X-ray absorption and diffraction studies

The potential of operando X-ray techniques for following the structure, fate, and active site of single-atom catalysts (SACs) is highlighted with emphasis on a synergetic approach of both topics. X-ray absorption spectroscopy (XAS) and related X-ray techniques have become fascinating tools to characterize solids and they can be applied to almost all the transition metals deriving information about the symmetry, oxidation state, local coordination, and many more structural and electronic properties. SACs, a newly coined concept, recently gained much attention in the field of heterogeneous catalysis. In this way, one can achieve a minimum use of the metal, theoretically highest efficiency, and the design of only one active site-so-called single site catalysts. While single sites are not easy to characterize especially under operating conditions, XAS as local probe together with complementary methods (infrared spectroscopy, electron microscopy) is ideal in this research area to prove the structure of these sites and the dynamic changes during reaction. In this review, starting from their fundamentals, various techniques related to conventional XAS and X-ray photon in/out techniques applied to single sites are discussed with detailed mechanistic and in situ/operando studies. We systematically summarize the design strategies of SACs and outline their exploration with XAS supported by density functional theory (DFT) calculations and recent machine learning tools.

The CARNAÚBA beamline is the tender-to-hard X-ray (2 – 15 keV) scanning nanoprobe planned for the 4th generation storage ring SIRIUS at the LNLS. CARNAÚBA uses an undulator source with vertical linear polarization in a low-beta straight section and grazing incidence-focusing mirrors to create a nanoprobe at 143 m from the source. The beamline optic is based on KB mirrors and provides high brilliance at an achromatic focal spot down to the diffraction limit diameter of ∼30 nm with a working distance of ∼6 cm. These characteristics are crucial for studying nanometric samples in experiments involving complex stages and environments. The CARNAÚBA beamline aims to perform raster scans using x-ray fluorescence, x-ray absorption spectroscopy, x-ray diffraction and coherent x-ray imaging techniques. Computed tomography will extend these methods to three dimensions.

The PdO-Pd phase transformation in a 4 wt% Pd/Al2O3 catalyst has been investigated using in situ X-ray absorption spectroscopy (XAS) and in situ X-ray total scattering (also known as high-energy X-ray diffraction) techniques. Both the partial and total pair distribution functions (PDF) from these respective techniques have been analysed in depth. New information from PDF analysis of total scattering data has been garnered using the differential PDF (d-PDF) approach where only correlations orginating from PdO and metallic Pd are extracted. This method circumvents problems encountered in characerising the catalytically active components due to the diffuse scattering from the disordered γ-Al2O3 support phase. Quantitative analysis of the palladium components within the catalyst allowed for the phase composition to be established at various temperatures. Above 850 °C it was found that PdO had converted to metallic Pd, however, the extent of reduction was of the order ca. 70% Pd metal and 30% PdO. Complementary in situ XANES and EXAFS were performed, with heating to high temperature and subsequent cooling in air, and the results of the analyses support the observations, that residual PdO is detected at elevated temperatures. Hysteresis in the transformation upon cooling is confirmed from XAS studies where reoxidation occurs below 680 °C.

Oxidation controlled phase composition of FeCo(Zr) nanoparticles in CaF2 matrix

Structural study of LiFePO4–LiNiPO4 solid solutions

X-ray absorption spectroscopy (XAS) is a popular technique for determining chemical states, such as oxidation states by XANES (x-ray absorption near edge structure) or interatomic distances and coordination numbers by EXAFS (extended x-ray absorption fine structure). These techniques are widely utilized by electrochemical researchers in synchrotron facilities worldwide, addressing a range of studies: for example, XANES can help to probe the oxidation states of battery electrode materials at various stages in their operational lifetime, EXAFS can elucidate the dynamics of conversion reactions in operando, thus capturing transients that may otherwise be lost in ex situ studies, and XAS experiments encompassing both XANES and EXAFS have shown unique promise for examining the behavior of sulfur in electrodes for Li-S batteries. The popularity of these techniques in tandem with the 3D microstructural information from X-ray tomography (XCT) and the compositional information available through other types of spectroscopy (e.g., XRF, EDS, and Raman) has grown substantially over the past two decades, as more synchrotron beamlines have become available for these experiments and the true power of the techniques have been demonstrated. In spite of the excitement generated by the various XAS experiments documented in the literature and the growing number of synchrotron facilities worldwide, access to suitable instrumentation remains challenging. This is due largely to the general popularity of synchrotron radiation for studying a variety of materials across a range of disciplines, leading to high levels of competition for limited amounts of available beam time. Efforts have been made in the past to migrate the XAS techniques to laboratory instrumentation, but such efforts have been met with many challenges. Often the exposure times are very long, resulting in multi-day measurements for a single experiment, or the energy resolution is too crude to provide sufficient sensitivity for precise quantification. Thus, a need remains for expanded access to XAS techniques within the electrochemical energy storage and conversion community, which has, so far, not been adequately addressed. Here, we present a novel, compact, laboratory-based XAS system operating in the 4.5-12 keV energy range with a powerful range of capabilities. This instrument provides sub-eV energy resolution over a fairly large energy range, short data collection times (seconds to minutes), and high spatial resolutions (~10 micrometers) for small spot analysis or mapping. The performance of the system is achieved in part with a patented high brightness x-ray source, a novel system design, and the use of the latest x-ray crystal analyzers and spatially resolved detector. Through the unique capabilities of this laboratory instrumentation, many experiments traditionally reserved for the synchrotron can now be accomplished in the laboratory. In this presentation, we will briefly review the spectrum of studies where XAS can provide insight into battery electrode materials and proceed to demonstrate how this laboratory XAS setup can address both routine and more specialized needs for electrochemical characterization. We will also discuss the relationship of this technique to other laboratory approaches, providing some perspectives on both the present and future of non-destructive characterization.

X-ray absorption spectroscopy (XAS) is a powerful experimental technique used to study the electronic structure and local environment of atoms in a material. It provides valuable insights into the chemical bonding, oxidation states, and coordination geometry of elements. XAS has been widely applied in various fields of electrochemistry, including popular topics like the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and CO2 reduction reaction (CO2RR).Despite the growing recognition of the practical importance of XAS techniques, correlating experimental spectroscopy with the working mechanisms and deciphering the structure of the electrochemical interface under reaction conditions remains challenging. In the case of CO2RR, we utilized operando XAS to investigate multiple Cu-based catalysts in different cell configurations. Our findings revealed that altering the reaction environment can induce an alternative pathway for catalyst structural changes. Moreover, operando XAS demonstrated that the reduction of Cu oxide catalysts is not solely governed by applied potentials but is also influenced by mass transport and other parameters. For ORR, in situ XAS not only provides information about the local environment changes of Pt-based catalysts but also unveils surface properties through △μ-X-ray adsorption near-edge spectroscopy (△μ-XANES). This further aids in the discovery of degradation mechanisms in proton exchange membrane fuel cells (PEMFCs). In the case of HER, in situ XAS enables characterization beyond catalysts and extends to the electrochemical interface.Overall, XAS techniques play a crucial role in understanding the electronic structure and local environment of atoms in electrochemical systems, shedding light on reaction mechanisms and catalyst performance under realistic conditions Acknowledgement The authors thank the funding source from Liquid Sunlight Alliance under the U.S. DOE, Office of Science, Office of Basic Energy Sciences, Fuels Award Number DE-SC0021266 and the Laboratory Directed Research and Development Program of the Lawrence Berkeley National Laboratory under the U.S. DOE Contract No. DE-AC02-05CH11231.

Teaching of statistics should focus more on practical data science, with a special emphasis on data wrangling: Preparing the data for the analyses, looking at the data via clever visualizations, and learning the principles and practices of open science and reproducible research. The statistics curriculum should be updated and the term “data science” used as a synonym to statistics. In all possible fields, there is a huge need to have more data scientists. To engage everyone with “open data science” (open data, open science, and data science), we have created a new course, where students from all levels and fields work together and share their ideas with openly available data sets and freely available state-of-the-art software tools, such as RStudio, R Markdown, and GitHub. The new course has been quite successful in engaging extremely heterogeneous groups of students to challenge themselves to a “next level” by learning new skills of open data science.

Synchrotron-based X-ray absorption spectroscopy (XAS), in the context of X-ray florescence (XRF) maps, is a powerful analytical tool that can define element speciation and characterize the local atomic structure of a suitable sample. While this type of analysis is regularly used to provide advances in a variety of scientific fields, including but not limited to material sciences, molecular physics, and medical sciences, it remains an underutilized tool in the (paleo)geosciences.  Here, we show that XAS can advance our knowledge of the Critical Zone in deep time. For this study, we used the X-ray fluorescence microprobe (XFM) beamline above the uranium (U) LIII-edge to create detailed XRF elemental maps. Based on these maps, we used X-ray absorption near edge spectroscopy (XANES) to probe U and Manganese (Mn) speciation of pedogenic carbonate nodules collected from Late Cretaceous paleosols from Big Bend National Park, Texas, USA.Pedogenic carbonate nodules are derived from soil waters that are oversaturated with respect to calcite. Accumulation of pedogenic calcite primarily occurs in semi-arid environments with mean annual precipitation ranging from 500-1200 mm/yr. Nodules are commonly used for uranium/thorium (U/Th) dating, atmospheric CO2 concentration(pCO2) reconstruction, and weathering intensity reconstruction using major and trace element concentrations. As prevalent as nodule research is in these various geological applications, little is known about the compositional variation on a microscale. We present and elucidate the texture, grainsize, and redox-sensitive elemental heterogeneity found within and between carbonate nodules. Preliminary results from U LIII-edge and Mn K-edge XANES showed primarily oxidized U and Mn.  XRF mapping of the samples indicate element discrimination between different carbonate fabrics as well as element zoning. The methods utilized in this study enable us to understand not only the microscale geochemistry of pedogenic carbonate nodules, but to provide an example of how XAS can be beneficial and useful for the paleoclimate and petrography community.