SPring-8 Synchrotron Radiation Facility Research Articles

Reconstruction of dendritic growth by fast tomography and phase field filtering

Three dimensional models of dendritic structures during solidification are valuable for building physical models, validating simulated results, estimating some properties such as permeability in the mushy, simulating semisolid deformation and so on. Thus, it is of interest to observe microstructure evolution in situ. Time-resolved tomography combined with X-ray diffraction has allowed us to observe the evolution of dendritic structures and to measure crystallographic orientation in situ. Reconstruction still proves to be difficult for some alloy systems because of the tradeoff between time and spatial resolution. This paper demonstrates the reconstruction of dendritic structures for three different alloy systems (Al-10mass%Cu alloy with a diameter of 4 mm, CrMnFeCoNi alloy with 1 mm, and Zn-4mass%Al alloy with 0.7 mm). The observations were performed in a synchrotron radiation facility SPring-8. A filter using a phase field model was introduced to reconstruct the three-dimensional images. Parameters used in the filtering were consistently determined based on the raw reconstruction images. Evaluation of solid-liquid interface area and curvature was significantly improved by the filter. For the Al-Cu alloy, a three-dimensional model containing approximately 300 million voxels was obtained. For the CrMnFeCoNi alloys, the preferred growth direction <100> was confirmed by tomography and X-ray diffraction. For the Zn-Al alloy, the observed 14 growth directions were not simply defined by the crystallographic orientations, although the directions were consistent with the hexagonal symmetry. This study verifies that time resolved tomography, X-ray diffraction and the filter using a phase field model provide three dimensional models for light metal alloys with rather large diameters and 3d transition-metal alloys with rather large X-ray absorption coefficients. The models are expected to be used for further studies.

白色X線応力測定法の基礎と応用

The X-ray diffraction method has been already established as one of the most effective nondestructive evaluation method of a stress in crystalline materials. Since white X-ray beam has a wide wavelength range, a diffraction angle has to fix during a measurement to obtain a lattice spacing using the Bragg’s low. Therefore, the white X-ray method has some different features from the characteristic X-ray method. For example, the information of lattice spacing of many lattice planes in a material can be obtained simultaneously on the same diffraction angle. Because all equipment are held fixed position during a measurement, it is advantageous to in-situ measurement under the special environment such as high temperature or high pressure. In the present review article, a brief history of development of the white X-ray method is covered and some factors related to the measurement accuracy is explained. Fundamentals of the measurement system using white X-ray and the energy dispersive method are presented. Applications of the method using white X-ray obtained from a rotating target type X-ray generator to the measurement of residual stress of a surface ground material and a coating material are described. Furthermore, applications of the method using high energy white X-ray generated in the synchrotron radiation facility SPring-8 to the measurement of internal strain of a material loaded by four-point bending and strain distribution in the vicinity of crack tip in a material introduced a fatigue crack are also described.

Three-dimensionally visualized rhizoid system of moss, Physcomitrium patens, by refraction-contrast X-ray micro-computed tomography.

Land plants have two types of shoot-supporting systems, root system and rhizoid system, in vascular plants and bryophytes. However, since the evolutionary origin of the systems is different, how much they exploit common systems or distinct systems to architect their structures is largely unknown. To understand the regulatory mechanism of how bryophytes architect the rhizoid system responding to environmental factors, we have developed the methodology to visualize and quantitatively analyze the rhizoid system of the moss, Physcomitrium patens, in 3D. The rhizoids having a diameter of 21.3 µm on the average were visualized by refraction-contrast X-ray micro-computed tomography using coherent X-ray optics available at synchrotron radiation facility SPring-8. Three types of shape (ring-shape, line and black circle) observed in tomographic slices of specimens embedded in paraffin were confirmed to be the rhizoids by optical and electron microscopy. Comprehensive automatic segmentation of the rhizoids, which appeared in three different form types in tomograms, was tested by a method using a Canny edge detector or machine learning. The accuracy of output images was evaluated by comparing with the manually segmented ground truth images using measures such as F1 score and Intersection over Union, revealing that the automatic segmentation using machine learning was more effective than that using the Canny edge detector. Thus, machine learning-based skeletonized 3D model revealed quite dense distribution of rhizoids. We successfully visualized the moss rhizoid system in 3D for the first time.

(Digital Presentation) Accelerated Degradation Mechanism of Ni-Rich Ncm Cathode Materials at High and Low Voltage Range Combined Cycling for Li-Ion Batteries

Lithium-ion batteries are widely used as power sources in electric buses, railways, ferries, and other mass transportation systems. To meet the energy needs of these infrastructure systems, it is important to realize battery control that enables high-energy operation for long periods of time. The high-capacity Ni-rich cathode material NCM811 (LiNi0.8Co0.1Mn0.1O2) has attracted research interest as a candidate high-energy-density cathode material. However, NCM811 has been reported to have some degradation problems, especially when operating at potential above 4.2 V versus Li/Li+1).Furthermore, the safety of NCM811 becomes compromised with time. Therefore, understanding the aging mechanism and predicting battery aging behavior are required for effective battery control. We have found that operating NCM811 cathodes at the combination of the potential higher than 4.2 V and lower potential less than 3.6 V that accelerates aging, leading to substantial capacity loss and increased resistance. However, aging was mitigated when NCM811 batteries were operated at a higher or lower potential range. Electrochemical and chemical analyses were performed to clarify the aging mechanism. We prepared 1-Ah LTO/NCM811 pouch cells. Charge/discharge cycling tests were carried out using various state-of-charge (SOC) ranges (SOC0-100%, SOC20-100%, and SOC0-70%) at a 3C rate at 65°C. When the cell was charged at SOC100% and SOC0%, the cathode potential was set to above 4.2 V and to below 3.6 V. The capacity retention and DC resistance (DCR: SOC50%, 0.2 sec) for these cells are shown in Figure1a. The capacity retention of the cell after 1000 cycles at SOC0-100% cycling test was about 75% for the initial capacity. However, a high capacity retention of 93% was obtained at SOC20-100% cycling, despite the cell was charged at SOC100% of 1000 times. The capacity retention of SOC0-70% cycling was nearly 100%. DCR increased 2.5-times after 1000 cycles at SOC0-100% cycling, which was higher increase than that of SOC20-100% cycling and SOC0-70% cycling. To clarify the mechanism, the cathode was removed from the deteriorated pouch cells and its electrochemical properties were investigated using a three-electrode glass beaker cell. The cell was assembled using the cathode and lithium metal as a counter electrode, and a reference electrode was also prepared. The lithium-diffusion coefficient of NCM811 at the time of preparation and after 1000 cycles was measured using the galvanostatic intermittent titration technique method. In the case of a NCM811 cathode operated at SOC0-100% for 1000 cycles, there was little change for the lithium-diffusion coefficient of x < 0.8 in LixNi0.8Co0.1Mn0.1O2, but that of x > 0.8 decreased to less than 1/10. Changes in the crystal structure of the NCM811 particle surface were analyzed by scanning transmission electron microscopy–electron energy loss spectroscopy (STEM-EELS). The thickness of the surface structural change layer was calculated from the EELS spectrum. Also, the thickness and composition of surface film was analyzed by hard X-ray photoelectron spectroscopy (HAX-PES). This measurement was performed at the SPring-8 synchrotron radiation facility. From the STEM-EELS analyses, in the case of SOC0-100% cycling, the surface crystal structure of NCM811 changed from the layered type to the rock-salt or spinel-layer type. The thickness of this transition layer increased by 7 nm compared from beginning. In the case of SOC0-70% cycling, the thickness increased by only 2 nm. It is expected that the cathode operated above 4.2 V at SOC0-100% cycling. From the HAX-PES analysis, the film thickness increased by 20 nm from the initial condition after SOC0-100% cycling. But, after SOC20-100% cycling and SOC0-70% cycling, the film thickness increased was suppressed than that. Based on the results of these analyses, we proposed the following model. In the first step, the structure change of NCM811 was accelerated at high potential. As the rock-salt layer disturbed lithium diffusion, the diffusional resistance increased and the capacity during discharge decreased. In the second step, when NCM811 subjected to a higher potential was discharged to a lower potential, the lithium can’t be intercalated smoothly at the surface x > 0.8 in LixNi0.8Co0.1Mn0.1O2. As a result, the lithium near the surface reacts with electrolyte, forming a film on the NCM811 surface. As the lithium was consumed by the film-growth reaction, the cathode operating potential increased, which accelerated the first step mechanism. The combination of the first and second steps accelerated aging. But this aging can be minimized by controlling the operating voltage. Understanding of the aging mechanism will enable accurate prediction of deterioration.[1]F. Friedrich, B. Strehle, etc, Journal of The Electrochemical Society, 166, A3760-A3774 (2019) Figure 1

Early Days of SACLA XFEL

The SACLA (SPring-8 Angstrom compact laser) was designed to significantly downsize the SASE (self-amplified spontaneous emission) type XFEL (X-ray free-electron laser), in order to generate coherent light in the wavelength region of 0.1 nm by adopting an in-vacuum undulator that can shorten the magnetic field period length. In addition, a SASE XFEL facility with a total length of 700 m has become a reality by using a C-band RF accelerating tube that enables a high acceleration gradient. Although progress was initially slow, the small-scale, low-cost SACLA was smoothly constructed, and it became the second light source to lase in the 0.1 nm wavelength region, following the LCLS (linac coherent light source) in the United States. In this paper, we look back on the history leading up to SACLA. and describe the SCSS (SPring-8 compact SASE source) project as a preparatory stage and a part of the construction/commissioning of SACLA. Since March 2012, SACLA has been operating as a shared user facility. Just a few of the upgrade activities of the facility and advanced research conducted are introduced. Finally, we will discuss the future development of the SPring-8 site, which has co-located the third-generation synchrotron radiation facility SPring-8 and the X-ray free-electron laser facility SACLA.

Crystal orientation and residual stress in TiN film by synchrotron radiation

Abstract The residual stress in a TiN film, the thickness of which is less than 1 µm, deposited by arc ion plating was measured using the SPring-8 synchrotron radiation facility installed at Japan Synchrotron Radiation Research Institute (JASRI). Films thicker than 300 nm have a {111} texture, whereas those with a thickness of 100 nm have a relatively random orientation. Instead of the conventional laboratory X-ray equipment, ultrabright synchrotron radiation can be used to precisely measure the residual stress in thin films with a thickness of 100 to 800 nm. The residual stress in thicker TiN films is about 7 GPa in compression and it is not affected by the film thickness. The slightly small compressive stress in a film of 100 nm in thickness may be due to the different crystal orientations in the film.

Chemical species of iodine during sorption by activated carbon -Effects of original chemical species and fulvic acids

ABSTRACT Radioactive iodine is one of the mobile radionuclides contained in the contaminated water generated by cooling of the fuel debris at Fukushima Daiichi nuclear power plant (FDNPP). It is reported that chemical species of iodine transform between iodate, iodide, and organo-I in the environments. In FDNPP, the contaminated water is merged with ground water containing fulvic acids and then passed through a series of treatment columns to remove radionuclides. The objective of this study was to determine if iodide or iodate speciation changed after it was sorbed by activated carbon (AC), a potential adsorbent at the FDNPP for waste water treatment. Chemical species of the sorbed iodine was determined by X-ray absorption near edge spectroscopy (XANES) at the SPring-8 Synchrotron Radiation Facility. Sorption experiments of iodate and iodide showed systematic decreases of the distribution coefficients with increasing pH of the solution. Additionally, greater sorption of iodate than iodide was measured. The novelty of these results includes that the chemical species of iodate and iodide on the AC did not change during sorption; however, the presence of fulvic acids promoted the transformation of iodate to the less strongly bound species, iodide, during sorption to AC. The results from this study have important implications on the long-term effectiveness and eventual disposal of used AC from the FDNPP facility.

Multilateral surface analysis of the CeB6 electron-gun cathode used at SACLA XFEL.

The CeB6(001) single crystal used as a cathode in a low-emittance electron gun and operated at the free-electron laser facility SACLA was investigated using cathode lens electron microscopy combined with X-ray spectroscopy at SPring-8 synchrotron radiation facility. Multilateral analysis using thermionic emission electron microscopy, low-energy electron microscopy, ultraviolet and X-ray photoemission electron microscopy and hard X-ray photoemission spectroscopy revealed that the thermionic electrons are emitted strongly and evenly from the CeB6 surface after pre-activation treatment (annealing at 1500°C for >1 h) and that the thermionic emission intensity as well as elemental composition vary between the central area and the edge of the old CeB6 surface.

Visualization of Arabidopsis root system architecture in 3D by refraction-contrast X-ray micro-computed tomography.

Plant roots change their morphological traits in order to adapt themselves to different environmental conditions, resulting in the alteration of the root system architecture. To understand this mechanism, it is essential to visualize the morphology of the entire root system. To reveal effects of long-term alteration of gravity environment on root system development, we have performed an experiment in the International Space Station using Arabidopsis plants and obtained dried root systems grown in rockwool slabs. The X-ray computed tomography (CT) technique using industrial X-ray scanners has been introduced to visualize the root system architecture of crop species grown in soil in 3D non-invasively. In the case of the present study, however, the root system of Arabidopsis is composed of finer roots compared with typical crop plants and rockwool is also composed of fibers having similar dimension to that of the roots. A higher spatial resolution imaging method is required for distinguishing roots from rockwool. Therefore, in the present study, we tested refraction-contrast X-ray micro-CT using coherent X-ray optics available at the beamline of the synchrotron radiation facility SPring-8 for bio-imaging. We have found that a wide field of view but with low resolution obtained at the experimental Hutch 3 of this beamline provided an overview map of the root systems, while a narrow field of view but with high resolution obtained at the experimental Hutch 1 provided an extended architecture of the secondary roots, by a clear distinction between roots and individual rockwool fibers, resulting in the successful tracing of these roots from their basal regions.

Effect of Cobalt Content on Charge Compensation Mechanism of LiNixMnyCozO2 Cathode for Lithium Ion Battery

LiCoO2 (LCO) is commonly used as a cathode for Li-ion batteries (LiBs) owing to its excellent intercalation nature, high voltage, and cyclic performance [1, 2]. However, LCO has issues due to the potential risk of future price increases of Co [3, 4]. Many efforts have been made to reduce the amount of Co in the cathode by replacing it with Ni and/or Mn, and LiNixMnyCozO2 (NMC) has been developed. NMC622, which contains 60 mol % of Ni in the transition metal composition, is now adopted in the majority of the electric vehicle battery chemistry. Although Ni-rich NMC is a promising alternative to low-Co cathodes, it is not clear whether the amount of Co can be further reduced from the present NMC622 without degrading cyclic stability. To further reduce the amount of Co, it is necessary to clarify the role of Co in the charge compensation mechanism and replace it with alternative elements with functions similar to those of Co.In this study, we conducted XAFS, XRD and first-principles calculations for the NMC cathode with various transition metal composition ratios to clarify that the roles of Co, Ni, Mn, and O in the charge compensation mechanism. Synchrotron X-ray experiments were performed at SPring-8 and NewSUBARU synchrotron radiation facility in Japan. The first-principles calculations were carried out with Vienna Ab-initio Simulation Package (VASP) [5, 6], which uses plane-wave basis sets.Fig. 1 shows the oxygen K-edge XANES spectra collected by the partial fluorescence yield (PFY) method at different states of charge (SOCs). As for the LCO, the peak intensity around 528 eV changed along with the SOC, suggesting that oxygen contributes to the charge compensation. Similar spectral changes were also observed with NMC111, NMC622, and slightly with NMC 811. In contrast, the white line energy in the Co L3-edge absorption hardly changed at any transition metal composition. Although there are various theories about the role of Co and oxygen in the charge compensation [7], our results show that there is no obvious change in the charge state of Co and oxygen contributes the most to the charge compensation in the LCO system. Detailed analysis including first-principles calculations will be discussed at the meeting.[1] K. Mizushima et al., Mater. Res. Bull. 15, 783 (1980).[2] A. Du Pasquier et al., J. Power Sources 115, 171 (2003).[3] P.A. Nelson et al., Modeling the Performance and Cost of Lithium-Ion Batteries for Electric-Drive Vehicles, Argonne National Laboratory, 2012.[4] Elsa A. Olivetti e t al., Joule 1, 229 (2017).[5] P. E. Blöch, Phys. Rev. B 50, 17953 (1994).[6] G. Kresse et al., Phys. Rev. B 59, 1758 (1999).[7] B. Li et al., Adv. Mater. 29, 1701054 (2017) Figure 1

In Situ Synchrotron Radiation XRD and XAFS Measurements of Multilayer All-Solid-State Lithium-Ion Batteries Using Li2CoP2O7 as a Positive Electrode Material

All-solid-state lithium-ion batteries are expected as next-generation batteries due to their safety and high volumetric energy density. We reported Li2CoP2O7 (LCPO) as a positive electrode material with charge/discharge reactions over 5 V. [1–3] In this study, the structural and valence change of LCPO in multilayer all-solid-state lithium-ion batteries during charge/discharge was investigated using in situ synchrotron radiation X-ray diffraction (XRD) and X-ray Absorption Fine Structure (XAFS) measurements.In multilayer all-solid-state lithium-ion batteries, LCPO was the positive electrode active material, Ti-based oxide was the negative electrode active material, and NASICON-type solid electrolyte was used as the solid electrolyte. Each material for the positive and negative electrodes and the solid electrolyte was made into a paste. They were laminated using a screen printing method and integrally sintered to produce multilayer all-solid-state batteries. Synchrotron radiation XRD and XAFS measurements were performed at the large synchrotron radiation facility SPring-8. In situ XRD was measured in a transmission mode using 30 keV X-rays for a multilayer all-solid-state battery. The X-ray beam had to pass through the center of the multilayer all-solid-state battery during the first charge/discharge reactions. In situ XAFS experiments were measured using a fluorescence method. XAFS scans covering the Co K edge peak were taken during the first charge/discharge reactions.Figure 1 shows the XRD patterns of the multilayer all-solid-state battery during the first cycle in the charge/discharge process. The main diffraction peaks of LCPO are located at around 13.0°, 14.4°, and 16.7°. The diffraction peak position at 16.7° gradually shifts to the lower degree side from its uncharged state and the peak intensity decreases during the charging process. In addition, the peak shift returns to the same position at the uncharged state during the discharging process. However, that is not completely. The diffraction peak intensity at 14.4° decreases. In the XAFS measurement results, the Co K edge spectrum shifts to the higher energy side compared to the uncharged state during the charging process. The Co K edge spectrum returns to the same energy position in the uncharged state during the discharging process. These results show that the valence of Co changes from 2+ to 3+ upon charging and returns from 3+ to 2+ upon discharging. We observed how the Co of the LCPO operates while the multilayer all-solid-state battery was charging and discharging.[1] A. Kato, The 395th Committee Of Battery Technology, (2019)[2] M. Kobayashi, et al., The 60th Battery Symposium, 2F19, (2019)[3] C. Yamamoto, et al., The 87th ECSJ Spring Meeting, (2020) Figure 1

Calculation of total scattering from a crystalline structural model based on experimental optics parameters.

Total scattering measurements enable understanding of the structural disorder in crystalline materials by Fourier transformation of the total structure factor, S(Q), where Q is the magnitude of the scattering vector. In this work, the direct calculation of total scattering from a crystalline structural model is proposed. To calculate the total scattering intensity, a suitable Q-broadening function for the diffraction profile is needed because the intensity and the width depend on the optical parameters of the diffraction apparatus, such as the X-ray energy resolution and divergence, and the intrinsic parameters. X-ray total scattering measurements for CeO2 powder were performed at beamline BL04B2 of the SPring-8 synchrotron radiation facility in Japan for comparison with the calculated S(Q) under various optical conditions. The evaluated Q-broadening function was comparable to the full width at half-maximum of the Bragg peaks in the experimental total scattering pattern. The proposed calculation method correctly accounts for parameters with Q dependence such as the atomic form factor and resolution function, enables estimation of the total scattering factor, and facilitates determination of the reduced pair distribution function for both crystalline and amorphous materials.

Visualization and quantification of the atrioventricular conduction axis in hearts with ventricular septal defect using phase contrast computed tomography

ObjectiveTo visualize and quantify the atrioventricular conduction axis in the setting of ventricular septal defect using phase contrast computed tomography. MethodsWe used the SPring-8 synchrotron radiation facility in Hyogo prefecture in Japan, processing and reconstructing the data with 3-dimensional software. ResultsWe studied 8 hearts obtained from patients known to have had ventricular septal defects, aged from 6 to 150 days, with a median of 24.5 days. None of the individuals, however, had undergone corrective surgery. The penetrating bundle was found at a median of 1.43 mm from the septal crest, with a range of 0.99 to 1.54 mm. The distance to the nonbranching bundle to the right ventricular endocardium was 1.10 mm, with a range from 0.49 to 2.49 mm, to the origin of the left bundle branch was 2.46 mm, with a range from 1.7 to 3.18 mm, and to the origin of the right bundle branch was 2.34 mm, with a range from 0.50 to 2.59 mm. The median distance from the edge of the caudal limb of the septomarginal trabeculation to the right bundle branch was 1.04 mm, with a range from 0.81 to 1.16 mm. ConclusionsWe were able to show the precise location of the axis, with our findings suggesting that longitudinal sutures placed along the posteroinferior rim should be effective in avoiding iatrogenic injury, but sutures should not be placed in the valley between the limbs of the septomarginal trabeculation.

Reassessment of the Location of the Conduction System in Atrioventricular Septal Defect Using Phase-Contrast Computed Tomography

The location of the atrioventricular conduction axis in the setting of atrioventricular septal defect has previously been shown by histology and intraoperative recordings. We have now reassessed the arrangement using phase-contrast computed tomography, aiming to provide precise measurements so as to optimize future surgical repairs. We used the system based on an X-ray Talbot grating interferometer using the beamline BL20B2 in a SPring-8 synchrotron radiation facility available in Japan. We analyzed 18 specimens. The atrioventricular node was found within a nodal triangle 1.7 mm from the coronary sinus, with 95% confidence intervals from 1.45 to 2.0 millimeters. The depth of the node from the right atrial endocardium was 1.0 mm, with 95% confidence intervals from 0.73 to 1.34 mm. The overall length of the scooped-out ventricular septum was 30.8 mm, with 95% confidence intervals from 27.5 to 34.1 millimeters. The length from the inferior atrioventricular junction to the take-off of the right bundle branch was 12.8 mm, with 95% confidence intervals from 11.12 to 14.38 mm, giving a ratio of 0.43 for the extent of the axis along the inferior septum, with 95% confidence intervals of 0.38-0.48. The length of the non-branching bundle was 6.6 mm, with 95% confidence intervals from 5.57 to 7.7 mm. The proportion of septum occupied by the non-branching bundle was 0.22, with 95% confidence intervals from 0.18 to 0.26. Our findings confirm previous histological studies, extending them by providing precise measurements to guide placement of sutures during surgical repair.

In Situ Synchrotron X-ray Diffraction Reciprocal Space Mapping Measurements in the RF-MBE Growth of GaInN on GaN and InN

In this work, in situ synchrotron X-ray diffraction reciprocal space mapping (RSM) measurements were carried out for the radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE) growth of GaInN on GaN and InN layers, which were also grown by RF-MBE on commercialized GaN/c-sapphire templates. In situ XRD RSM measurements were performed using an MBE apparatus directly coupled to an X-ray diffractometer at the beamline of the synchrotron radiation facility SPring-8. It was observed in situ that both lattice relaxation and compositional pulling occurred during the initial growth stage, reducing the strain of GaInN on GaN and InN. Different initial growth behaviors of GaInN on GaN and InN were also observed from the results of the evolution of GaInN integrated peak intensities.

Interfacial Behavior of Magnesium Ions at Electrode/Electrolyte Interface during Magnesium Deposition Reaction

Introduction Magnesium has large theoretical volumetric capacity and high negative, also much cheaper than metal lithium on price and simple process for handle. Due to the higher safety compared with lithium batteries. rechargeable magnesium batteries with magnesium as the anode has become a hot spot of the study. Electrolyte for magnesium rechargeable batteries has been developed by Aurbach and co-worker [1,2], in which Grinard reagents are contained. The anodic stability and chemical stability of the Grignard reagents-based electrolyte is not satisfied with practical application. [3]. For the development of rechargeable magnesium batteries, it is necessary to elucidate the reaction mechanism at electrolyte/magnesium metal interface. The key factor that predominates the reaction mechanism is considered to be the coordination structures of magnesium ions in the bulk electrolyte solution and at the negative electrode surface. In this study, we examined the mechanism of magnesium deposition/dissolution reactions in the magnesium bis(trifluoromethanesulfonyl)amide Mg(TFSA)2/triglyme electrolyte, and compared them with those in Mg(AlCl2EtBu)2/tetrahydrofuran (THF) and Mg(TFSA)2/2-methyltetrahydrofuran (2-MeTHF)). The bulk structures of the electrolytes were examined by Raman spectroscopy and the theoretical calculation. And then, we applied operando soft X-ray absorption spectroscopy(XAS) to examine the electronic and local structure of magnesium ions at negative electrode/electrolyte interface during magnesium deposition. Experiments Electrochemical properties of the electrolyte were investigated by cyclic voltammetry with the three-electrode cell. The deposition after electrochemical measurement was characterized by XRD and SEM. The operando XAS spectra for Mg K-edge of the electrolytes were measured by the partial fluorescence yield method at the SPring-8 synchrotron radiation facility (BL27SU) in Hyogo, Japan [4]. Results and discussion In cyclic voltammetry, the currents attributed to magnesium deposition/dissolution reactions occurred in Mg(TFSA)2/triglyme and Mg(AlCl2EtBu)2/THF were observed. The currents were not observed in Mg(TFSA)2/2-MeTHF. operando XAS measurements supported that valence of magnesium ions did not change and local structure distortion around magnesium ions increased in Mg(TFSA)2/triglyme and Mg(TFSA)2/2-MeTHF at the magnesium electrode | electrolyte interface during cathodic polarization. These results indicate that the difference of the behavior of magnesium deposition should be affected by the difference of coordinate structure of [TFSA]- in both electrolytes. Our DFT calculation results indicate that the [TFSA]- strongly bound to magnesium ion in Mg(TFSA)2/2-MeTHF electrolyte undergoes reduction decomposition easily instead deposition of magnesium metal, which makes the electrolyte inactive electrochemically. On the other hand, because the [TFSA]- weakly bound to magnesium ion in Mg(TFSA)2/triglyme, the reduction decomposition occurs relatively slowly, which allows magnesium deposition in the electrolyte. We conclude that controlling the interaction between Mg2+ and [TFSA]- and suppressing reduction decomposition of [TFSA]- is crucial to achieve successful magnesium deposition.

Characterization of dendritic growth in Fe–C system using time-resolved X-ray tomography and physics-based filtering

Time-resolved in situ tomography of dendritic growth in Fe–0.45 mass% C carbon steel was performed using synchrotron radiation X-rays at SPring-8 synchrotron radiation facility (Japan) with improvement of the image quality using a physics-based filter. The voxel size of the reconstructed image was approximately 6.5 μm × 6.5 μm × 6.5 μm, and the time resolution (duration of 360° rotation) was 4 s (0.25 rps). Three-dimensional images of the dendrites were reconstructed even without image processing; however, the low contrast resolution in Fe–C alloys led to poor image quality. Consequently, it was impossible to precisely track the solid/liquid interface or evaluate the average curvature. To improve the image quality, a physics-based filter (a PF filter) was developed using a phase-field model. In the PF filter, images were retrieved in terms of interface curvature. The PF filter significantly improved the computed tomography image quality. As a result, dendritic growth was clearly observed even in Fe–C alloys. Moreover, the average curvature of the solid/liquid interface was evaluated as a function of solidification time (solid fraction). The ability to systematically characterize growing dendrites will be beneficial for modeling and simulation of solidification phenomena.

X-ray ring-focusing mirror

Mirrors used in synchrotron radiation facilities can reflect X-ray beams ideally owing to recent advancements in ultraprecise fabrication technologies. Flat mirrors can change the direction of an X-ray beam without distorting its wavefront. Elliptically figured mirrors can focus X-rays onto a spot with nanometer dimensions. The intensity distribution of a reflected X-ray beam is determined, and thus can be controlled, by the shape of the employed mirror. This study proposes, fabricates, and evaluates a ring-focusing mirror that can produce an X-ray beam with a ring-shaped intensity profile. This ring-shaped X-ray beam could be created and observed at the soft X-ray beamline BL25SU at the SPring-8 synchrotron radiation facility, Japan. The increase in the freedom of X-ray mirror shapes will lead to the development of various analytical methods and optical systems in the X-ray region.

SPring-8 BL36XU: Synchrotron Radiation X-Ray-Based Multi-Analytical Beamline for Polymer Electrolyte Fuel Cells under Operating Conditions.

We designed and constructed a beamline BL36XU at the 8 GeV synchrotron radiation facility SPring-8 to provide information required for the development of next-generation polymer electrolyte fuel cells (PEFCs) by clarifying the dynamic aspects of structures and electronic states of cathode catalysts under PEFC operating conditions and in the deterioration processes by accelerated durability test protcols. To investigate the mechanism and degradation process for the cathode electrocatalysis in practical PEFCs, we developed advanced time- and spatially-resolved in-situ/operando X-ray absorption fine structure measurement systems and complementary analytical systems (X-ray emission spectroscopy (XES), X-ray diffraction (XRD), X-ray computer tomography (CT) and hard X-ray photoelectron spectroscopy (HAXPES)) and combined them to develop multi-analytical systems at BL36XU. Multi-analytical systems are very powerful for observing spatial-temporal features of the transient processes occurring in complex systems such as PEFCs. This account describes the design, performance, and research results of the BL36XU and multi-analytical in-situ/operando systems.

Deep core photoionization of iodine in CH3I and CF3I molecules: how deep down does the chemical shift reach?

Hard X-ray electron spectroscopic study of iodine 1s and 2s photoionization of iodomethane (CH3I) and trifluoroiodomethane (CF3I) molecules is presented. The experiment was carried out at the SPring-8 synchrotron radiation facility in Japan. The results are analyzed with the aid of relativistic molecular and atomic calculations. It is shown that charge redistribution within the molecule is experimentally observable even for very deep levels and is a function of the number of electron vacancies. We also show that the analysis of Auger spectra subsequent to hard X-ray photoionization can be used to provide insight into charge distribution in molecules and highlight the necessity of quantum electrodynamics corrections in the prediction of core shell binding energies in molecules that contain heavy atoms.