Synchrotron Rad Research Articles

In situ beamline analysis and correction of activeoptics. Erratum.

A correction to one of the equations in the paper by Sutter et al. (2012). [J.Synchrotron Rad. 19, 960-968] is made.

Effective aperture of X-ray compound refractive lenses.

A new definition of the effective aperture of the X-ray compound refractive lens (CRL) is proposed. Both linear (one-dimensional) and circular (two-dimensional) CRLs are considered. It is shown that for a strongly absorbing CRL the real aperture does not influence the focusing properties and the effective aperture is determined by absorption. However, there are three ways to determine the effective aperture in terms of transparent CRLs. In the papers by Kohn [(2002). JETP Lett. 76, 600-603; (2003). J. Exp. Theor. Phys. 97, 204-215; (2009). J. Surface Investig. 3, 358-364; (2012). J. Synchrotron Rad. 19, 84-92; Kohn et al. (2003). Opt. Commun. 216, 247-260; (2003). J. Phys. IV Fr, 104, 217-220], the FWHM of the X-ray beam intensity just behind the CRL was used. In the papers by Lengeler et al. [(1999). J. Synchrotron Rad. 6, 1153-1167; (1998). J.Appl. Phys. 84, 5855-5861], the maximum intensity value at the focus was used. Numerically, these two definitions differ by 50%. The new definition is based on the integral intensity of the beam behind the CRL over the real aperture. The integral intensity is the most physical value and is independent of distance. The new definition gives a value that is greater than that of the Kohn definition by 6% and less than that of the Lengeler definition by 41%. A new approximation for the aperture function of a two-dimensional CRL is proposed which allows one to calculate the two-dimensional CRL through the one-dimensional CRL and to obtain an analytical solution for a complex system of many CRLs.

Study on the reflectivity properties of spherically bent analyser crystals. Corrigendum.

Corrections to the paper by Honkanen et al. (2014). [J. Synchrotron Rad. 21, 104-110] are made.

Site-Selective and Element-Selective Analysis of Nickel Substituted Li-Rich Layered Material Using By X-Ray Diffraction and Absorption Spectroscopy

1. Introduction Li-rich type (manganese) oxides are one of the most featured cathodes for lithium ion batteries in recent years, owing to their high capacity and cyclability. In these cathodes, partial substitution of manganese by other transition metals such as Ni and Co has been proposed and shown to be effective in improving the performance, [1] however, the role of such metals in the battery performance has not been clarified in detail.We have synthesized Ni ion substituted Li excess manganese oxides (Li2Mn1-xNixO3) as a simple model of Li2MeO3 phase in solid solution cathode to understand the effect of introduced Ni by using the combination of in situ X-ray absorption spectroscopy (XAS) and X-ray diffraction spectroscopy (XDS) analysis. Diffraction anomalous fine structure (DAFS) spectra are achieved by XDS analysis, that there were quantitatively showed potential-dependent transbilayer migration of nickel and manganese and their reversibility. 2. Experimental procedure The active material of nickel substituted Li2MnO3 (Li2Mn1-x NixO3, x = 0 ~ 0.25) was prepared from solid phase calcination at 1173 K for 12 h in air. The working electrode consisted of active material (80 wt.%), acetylene black (10 wt.%) and polyvinylidene difluoride (PVdF) binder (10 wt.%), coated on aluminum current foil.The electrochemical measurements of the electrode were employed using aluminum pouch type cells, metallic lithium as counter and reference electrodes, 1 mol dm-3 LiPF6 in a 3:7 mixture of EC/DMC, and a polyolefin film as a separator. The electrochemical charge and discharge tests were performed at room temperature and the potential range was between 2.0 and 4.8 V.XAS measurements were performed by the three-electrode cell with charging and discharging processes (in Operando). The XAS measurements of the Ni-K and Mn-K edge region were performed using a solid-state detector at beamlines BL28XU in SPring-8 (Hyogo, Japan).The XDS measurements were conducted at beamline BL28XU, SPring-8, Japan. A two-dimensional Pilatus detector (Dectris Co., Ltd.) was mounted onto an arm of a multi-axis goniometer and was used to measure the diffraction profile, and two ionization chamber was used for the absorption correction of the DAFS spectra. 3. Results and Discussion The obtained X-ray absorption near edge structure (XANES) region spectra at N-K energy region of Li2Mn1-x NixO3 (x = 0.25) in the 1st charging and discharging processes are shown in Fig. 1. The edge energy was shifted to high energy, which is suggested that Ni element function as a charge compensation species. However the end of charging region around 4.7 V to 4.8 V was shifted to low energy as seen in previous XAS report [2], which means the reduction of nickel on average in this region.As our group have published before,[3] XANES-like spectra only from selected sites (i.e. DAFS spectra) can be extracted from the XDS analysis. Fig. 2 shows the DAFS spectra of initial sample. The Ni-K edge XANES-like spectra shows that there was cation mixing in the lithium layer of the pristine material. In contrast, Mn-K edge XANES-like spectra shows that manganese mostly occupied in transition metal layer. XDS analysis of the fully charged sample indicated that Ni element further migrated to the lithium layer.These analytical approaches are important to understand the metal migration behavior as a function of operation potential together with the charge compensation mechanism during electrochemical charging and discharging.

Low-temperature powder X-ray diffraction measurements in vacuum: analysis of the thermal displacement of copper

A serious limitation of the all-in-vacuum diffractometer reported by Straasø, Dippel, Becker & Als-Nielsen [J. Synchrotron Rad.(2014),21, 119–126] has so far been the inability to cool samples to near-cryogenic temperatures during measurement. The problem is solved by placing the sample in a jet of helium gas cooled by liquid nitrogen. The resulting temperature change is quantified by determining the change in unit-cell parameter and atomic displacement parameter of copper. The cooling proved successful, with a resulting temperature of ∼95 (3) K. The measured powder X-ray diffraction data are of superb quality and high resolution [up to sinθ/λ = 2.2 Å−1], permitting an extensive modelling of the thermal displacement. The anharmonic displacement of copper was modelled by a Gram–Charlier expansion of the temperature factor. As expected, the corresponding probability distribution function shows an increased probability away from neighbouring atoms and a decreased probability towards them.

Characterization of Cracks and their Effects on the Effective Transport Pathways in Ni-YSZ Anodes after Reoxidation Using X-Ray Nanotomography

Reduction-oxidation (redox) cycling of Ni-based electrodes for solid oxide fuel/electrolysis cell irreversibly alters their microstructure and can cause the fracture of the electrolyte. Non-destructive 3-D imaging techniques enable tracking the microstructural changes that occur during the cycling [1]. Despite the recent advances, the understanding of how local 3-D geometrical features in the heterogeneous electrode material contribute to the material degradation remains incomplete. Absorption contrast X-ray nanotomography (XNT) of a same Ni(O)-yttria-stabilized zirconia (YSZ) sample was performed at the NiO K-edge white-line peak (8348 eV), before and after exposure to air at 800°C during 45 minutes. A complimentary XNT at 8376 eV confirmed a degree of oxidation in the range of 98%. The morphology of the Ni(O) phase was as expected completely different after re-oxidation. The spatial resolution in the range of 20 nm [2] further enabled the detection of cracks in the brittle YSZ phase. 3-D local curvature measurements were first performed to identify and characterize the crack initiation sites. Then, the capabilities of simple fracture mechanics models combined with curvature measurements were tested in the view of rapidly pinpointing the locations vulnerable to redox cycling. Finally, the detrimental effects of the cracks on the effective 3-D transport pathways in the Ni-YSZ anode under polarization was investigated using a skeleton-based discrete representation of the imaged volume and an analytical electrochemical fin model [3]. Topological properties, effective ionic conductivity and polarization resistance were calculated before and after oxidation. For the latter estimate, the effect of cracked YSZ network was considered first alone; that of the spatial re-distribution of triple-phase boundaries induced by re-oxidation will be included in the future. [1] A. M. Kiss, W. M. Harris, S. Wang, J. Vila-Comamala, A. Deriy and W. K. S. Chiu, Applied Physics Letters 102 (2013) 053902. [2] J. Vila-Comamala, Y. Pan, J. J. Lombardo, W. M. Harris, W. K. S. Chiu, C. David, Y. Wang, J. Synchrotron Rad. 19 (2012), 705–709. [3] G. J. Nelson, A. Nakajo, B. N. Cassenti, M. B. DeGostin, K. R. Bagshaw, A A. Peracchio, G. Xiao, S. Wang, F. Chen, W. K. S. Chiu, Journal of Power Sources 246 (2014) 322-334.

Analysis of multicrystal pump-probe data sets. I. Expressions for the RATIO model.

The RATIO method in time-resolved crystallography [Coppens et al. (2009). J. Synchrotron Rad. 16, 226-230] was developed for use with Laue pump-probe diffraction data to avoid complex corrections due to wavelength dependence of the intensities. The application of the RATIO method in processing/analysis prior to structure refinement requires an appropriate ratio model for modeling the light response. The assessment of the accuracy of pump-probe time-resolved structure refinements based on the observed ratios was discussed in a previous paper. In the current paper, a detailed ratio model is discussed, taking into account both geometric and thermal light-induced changes.

In Situ XANES Analysis of Olivine-Type Cathode Materials to Study Kinetically Preferred State

Introduction Yao et al. invented "relaxation analysis" to make transition of electrode materials from kinetically preferred state to equilibrium state clear. Olivine-type cathode materials are included in it1-3. These materials are promising, having both large theoretical capacity and fine stability4. Previously, Park et al. found that the amount of LiFePO4 decreased and that of FePO4 increased at the relaxation process after the termination of lithium insertion by use of relaxation analysis2. They considered that the LiFePO4 including lithium defects preferable for Li diffusion formed during lithium insertion process and that the defective LiFePO4 separated to LiFePO4 without defects and FePO4 at the relaxation process. Synchrotron X-ray absorption near edge structure (XANES) method is a powerful tool to investigate the structural/electronic properties. XANES enable to measure the kinetically-preferred state directly during a reaction. In this study, we measured the in situ Fe K-edge XANES of LiFePO4 cathode during lithium insertion for the purpose of investigating the kinetically-preferred structure and comparing the result with that of relaxation analysis obtained by using the XRD-Rietveld method2. Experimental Cathode was prepared by mixing LiFePO4, carbon black, and polyvinylidenefluoride with a weight ratio of 70:15:15 in N-methlpyrrolidone solution. The slurry was spread onto aluminum foil current collector and dried in a 120°C vacuum oven. The cathode and lithium metal anode were separated by a polypropylene membrane separator. LiPF6 (1 M) in ethylene carbonate/diethyl carbonate (EC/DEC) (3:7 v/v) was used as the electrolyte. The 2032-type coin cell with X-Ray window was assembled in an argon-filled glove box. We first charged the cell to 4.0 V at a rate of 0.19 C and took 12 minutes for rest when the voltage got to 4.0 V. We subsequently discharged the cells at a rate of 0.32 C to 2.65 V. In situ Fe K-edge XANES measurement was performed in transmission mode at beamline 5S1 of Aichi Synchrotron Radiation Center. We took 3 minutes measurement and 1 minute interval per scan; the scan range was 150 eV before the Fe K absorption edge and 1000 eV after that. We merged three continuous patterns into one pattern to decrease noise and to improve the analysis precision. The composition x in Li(1-x)FePO4 of each merged pattern was calculated by integrating the current. We carried out a two-components analysis based on the linear combination of the last merged pattern, called Li-rich phase hereafter, and the merged pattern during the rest time before lithium insertion, called Li-lean phase hereafter, for either end by using Athena5program. Results and Discussion The composition of Li-lean phase and Li-rich phase were calculated as Li0.09FePO4 and Li0.85FePO4 respectively by using the integrating current. Figure 1 shows an example of two-components analysis for the composition of x = 0.28 in Li(1-x)FePO4 . The XANES pattern was well fitted with a low χ2value of 0.15%. It was found that the relative amount of Li-rich phase from two components analysis, 89.6%, was larger than the amount, 82.9%, calculated from the composition x in Li(1-x)FePO4. The large amount of Li-rich phase out of linear relationship may indicate that Li-rich phase with lithium defects formed in large amount during lithium insertion process. This is consistent with the result of the "Relaxation Analysis"2using the XRD-Rietveld method. [1] S. Park, M. Oda and T. Yao, Solid State Ionics 203(2011) 29-32.[2] S. Park, K. Kameyama and T. Yao, Electrochem. solid-state lett. 15(2012) A49-A52[3] Y. Satou, S. Komine, S. Park and T. Yao, Solid State Ionics, In Press[4] A. K. Padhi, K. S. Nanjundaswamy and J. B. Goodenough, J. Electrchem. Soc. 144(1997) 1188-1194[5] B. Ravel and M. Newville, J. Synchrotron Rad. 12(2005) 537-541

Improving the energy resolution of bent crystal X-ray spectrometers with position-sensitive detectors.

Wavelength-dispersive high-resolution X-ray spectrometers often employ elastically bent crystals for the wavelength analysis. In a preceding paper [Honkanen et al. (2014). J. Synchrotron Rad. 21, 104-110] a theory for quantifying the internal stress of a macroscopically large spherically curved analyser crystal was presented. Here the theory is applied to compensate for the corresponding decrease of the energy resolution. The technique is demonstrated with a Johann-type spectrometer using a spherically bent Si(660) analyser in near-backscattering geometry, where an improvement in the energy resolution from 1.0 eV down to 0.5 eV at 9.7 keV incident photon energy was observed.

Compton Scattering Imaging for in-Situ and Operando Analyses of Working Batteries

An ever-increasing demand for high-performance batteries has spurred a research activity in search of proven, in-situ and operando techniques for monitoring the electrochemical reactions and structural changes that occur inside a working battery. Here we propose an X-ray imaging technique based on synchrotron X-ray Compton scattering and demonstrate its application to batteries. The technique uses monochromatic X-rays as the probe, and detects Compton scattered X-rays from a certain volume element inside a battery. Both X-rays are higher than 100 keV with high penetration power into materials and X-ray Compton scattering is sensitive to the constituent elements [1], which enables the electrochemical and structural analyses under the in-situ and operando condition. In this paper, we present the outline of Compton scattering imaging (CSI), its application to a commercial coin battery and the future direction of this technique.The CSI technique provides three-dimensional images of the electron density distribution of an object without the need of observations from all surrounding directions [2, 3]. Because of high sensitivity to low-Z element materials, the technique with a conventional X-ray source or gamma-ray source has been used in the medical field and in the food and agricultural industries. The drawbacks of the technique were the relatively low counting rate and large probing volume element, but these have been overcome by the use of synchrotron X-rays and related focusing X-ray optics [4]. Synchrotron radiation based CSI (SR-CSI) has now been developed to such that it can provide the dynamic images of the electron density distribution inside a working battery.As a demonstration, we have measured the intensity of Compton scattered X-rays from the discharging coin cell (CR2032) as a function of one-dimensional position inside the cell and discharging time (see Figure). The position-time intensity map captures the migration of lithium ions in the positive electrode and reveals the change in position of the separator due to the volume expansion of the electrode. The experiment was performed at the BL08W beamline of SPring-8, Japan. The incident 115 keV X-ray beams with a size of 20μm(v)x500μm(h) were guided to the coin cell and Compton scattered X-rays from a volume element inside the cell were collected with a Ge solid state detector at a scattering angle of 90 degrees. Placing a slit with a width of 500μm in front of the detector, the volume element at each position was 20μmx500μmx500μm. This demonstration is a critical step for further development.We are developing the SR-CSI technique for larger Li batteries such as those mounted in plug-in hybrid electric vehicles or in electric vehicles. The challenges are to reduce the probing volume element and to enhance the detection efficiency. We will present the future direction along this line. This work is supported by the Development of Systems and Technology for Advanced Measurement and Analysis program under Japan Science and Technology Agency.[1] M. J. Cooper, Rep. Prog. Phys. 48 (1985) 415-481.[2] J. M. Sharaf, Applied Radiation and Isotopes, 54(2001) 801-809.[3] G. Harding and E. Harding, Applied Radiation and Isotpes, 68(2010) 993-1005.[4] A. Andrejczuk, M. Nagamine, Y. Sakurai and M. Itou, J. Synchrotron Rad. 21(2014)57-60.

Evolution of Chemical and Morphological Changes of High Capacity Electrode Materials Across Multiple Lengths Scales

Understanding and quantifying the changes in chemical composition as well as morphology of battery materials under electrochemical cycling is fundamental to their long cycle life and safety1-2. This is particularly true for high energy density lithium-manganese rich cathodes which transitions from a high voltage layered–layered phase to a defect type spinel phase under constant electrochemical cycling. In this study we combine the full-field transmission X-ray microscopy (TXM) and the X-ray absorption near edge structure (XANES) to spatially resolve and map the accompanying chemical phase change and morphology of a high voltage lithium-ion cathode composition, Li1.2Mn0.525Ni0.175Co0.1O2, (LMR-NMC)3 at a resolution down to 30 nm over a fields-of-view of several tens of microns. 2D TXM-XANES imaging was conducted on a series of samples recovered at different stages of the battery cycling, showing that the material experiences phase segregation of various transition metal species from the particle bulk to surface4. Energy-resolved 3D morphology and quantification analysis with elemental information suggested that the distribution of three transition metal is heterogeneous and the surface of material particle constantly evolves with electrochemical cycling with varied average concentration of Mn, Co and Ni compared to particle internal.These results will be compared with results obtained from confocal ex-situ Raman mapping for pristine and cycled LMR-NMC composite cathodes. Raman results provide important information regarding the chemical homogeneity of the electrodes with respect to active material, binder and carbon additive distribution and their changes under high voltage electrochemical cycling. Florian Meirer, Jordi Cabana, Yijin Liu, Apurva Mehta, Joy C. Andrews and Piero Pianetta, J. Synchrotron Rad,. 18, 773 (2011).Wen-Chin Chen, Yen-Fang Song, Chun-Chieh Wang, Yijin Liu, Darius T. Morris,Piero A. Pianetta, Joy C. Andrews, Hung-Chun Wud and Nae-Lih Wu, J. Mater. Chem. A 1, 10847. (2013).Surendra K. Martha, Jagjit Nanda, Gabriel Veith Nancy J. Dudney, J Power Sources 199, 220 (2012)Fei fei Yang et al. Under preparation (2014)

Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling. Erratum

Corrections to the article by Mayeret al.[J. Synchrotron Rad.(2013),20, 433–440] are given.

ANKAphase: software for single-distance phase retrieval from inline X-ray phase-contrast radiographs. Erratum

An equation in the paper by Weitkampet al.[(2011),J. Synchrotron Rad.18, 617–629] is corrected.

Novel energy resolving x-ray pinhole camera on Alcator C-Mod

A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of ≈1 cm, an energy resolution of ≈1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009)] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

On the calculation of the gauge volume size for energy-dispersive X-ray diffraction. Erratum

An equation in the paper by Rowles [(2011),J. Synchrotron Rad.18, 938–941] is corrected.

Two-dimensional approach to fluorescence yield XANES measurement using a silicon drift detector. Erratum

An error in the paper by Tamenoriet al.[(2011),J. Synchrotron Rad.18, 747–752] is corrected.

Calcifications in human osteoarthritic articular cartilage:ex vivoassessment of calcium compounds using XANES spectroscopy. Addendum

An acknowledgment is published for the paper by Nguyenet al.[(2011),J. Synchrotron Rad.18, 475–480].

Blueprint XAS: aMatlab-based toolbox for the fitting and analysis of XAS spectra

Blueprint XAS is a new Matlab-based program developed to fit and analyse X-ray absorption spectroscopy (XAS) data, most specifically in the near-edge region of the spectrum. The program is based on a methodology that introduces a novel background model into the complete fit model and that is capable of generating any number of independent fits with minimal introduction of user bias [Delgado-Jaime & Kennepohl (2010), J. Synchrotron Rad. 17, 119-128]. The functions and settings on the five panels of its graphical user interface are designed to suit the needs of near-edge XAS data analyzers. A batch function allows for the setting of multiple jobs to be run with Matlab in the background. A unique statistics panel allows the user to analyse a family of independent fits, to evaluate fit models and to draw statistically supported conclusions. The version introduced here (v0.2) is currently a toolbox for Matlab. Future stand-alone versions of the program will also incorporate several other new features to create a full package of tools for XAS data processing.

Development and exploration of a new methodology for the fitting and analysis of XAS data

A new data analysis methodology for X-ray absorption near-edge spectroscopy (XANES) is introduced and tested using several examples. The methodology has been implemented within the context of a new Matlab-based program discussed in a companion related article [Delgado-Jaime et al. (2010), J. Synchrotron Rad. 17, 132-137]. The approach makes use of a Monte Carlo search method to seek appropriate starting points for a fit model, allowing for the generation of a large number of independent fits with minimal user-induced bias. The applicability of this methodology is tested using various data sets on the Cl K-edge XAS data for tetragonal CuCl(4)(2-), a common reference compound used for calibration and covalency estimation in M-Cl bonds. A new background model function that effectively blends together background profiles with spectral features is an important component of the discussed methodology. The development of a robust evaluation function to fit multiple-edge data is discussed and the implications regarding standard approaches to data analysis are discussed and explored within these examples.

PILATUS: A single photon counting pixel detector for X-ray applications

The hybrid pixel technology combines silicon sensors with CMOS-processing chips by a 2D micro bump-bonding interconnection technology developed at Paul Scherrer Institute [C. Broennimann, E.F. Eikenberry, B. Henrich, R. Horisberger, G. Huelsen, E. Pohl, B. Schmitt, C. Schulze-Briese, M. Suzuki, T. Tomizaki, H. Toyokawa, A. Wagner. J. Synchrotron Rad. 13 (2005) 120 [1]; T. Rohe, C. Broennimann, F. Glaus, J. Gobrecht, S. Heising, M. Horisberger, R. Horisberger, H.C. Kaestl, J. Lehmann, S. Streuli, Nucl. Instr. and Meth. Phys. Res. A 565 (2006) 303 [2]]. PILATUS hybrid pixel detectors like other instruments [X. Llopart, M. Campell, R. Dinapoli, D. San Segundo, E. Pernigotti. IEEE Trans. Nucl. Sci. 49 (2002) 2279 [3]; N. Boudet, J.-F. Berar, L. Blanquart, P. Breugon, B. Caillot, J.-C. Clemens, I. Koudobine, P. Delpierre, C. Mouget, R. Potheau, I. Valin, Nucl. Instr. and Meth. Phys. Res. A 510 (2003) 41 [4]] are operating in the so-called “single photon counting mode”: Every X-ray quantum is directly converted into an electrical signal and counted by the detector system. Several prototype detectors in various geometries were produced, tested and established at different synchrotron beamlines worldwide. We explain the technology and present some recent highlights from various fields of applications.