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The hydrogen desorption and absorption reactions of the complex metal hydride NaAlH4 are disproportionation processes, and the kinetics can be improved by adding a few mol% of Ti compounds, although the catalytic mechanism, including the location and state of Ti, remains unknown. In this study, we aimed to reveal the generating mechanism of catalytic Al–Ti alloy in NaAlH4 with TiCl3 using quantum multiprobe techniques such as neutron diffraction (ND), synchrotron X-ray diffraction (XRD), anomalous X-ray scattering (AXS), and X-ray absorption fine structure (XAFS). Rietveld refinements of the ND and XRD, profiles before the first desorption of NaAlD(H)4–0.02TiCl3 showed that Al in NaAlD(H)4 was partially substituted by Ti. On the other hand, Ti was not present in NaAlH4, and Al–Ti nanoparticles were detected in the XRD profile after the first re-absorption. This was consistent with the AXS and XAFS results. It is suggested that the substitution promotes the formation of a highly dispersed nanosized Al–Ti alloy during the first desorption process and that the effectiveness of TiCl3 as an additive can be attributed to the dispersion of Ti.

Ice polymorphs show extraordinary structural diversity depending on pressure and temperature. The behavior of hydrogen-bond disorder not only is a key ingredient for their structural diversity but also controls their physical properties. However, it has been a challenge to determine the details of the disordered structure in ice polymorphs under pressure, because of the limited observable reciprocal space and inaccuracies related to high-pressure techniques. Here, we present an elucidation of the disordered structure of ice VII, the dominant high-pressure form of water, at 2.2 GPa and 298 K, from both single-crystal and powder neutron-diffraction techniques. We reveal the three-dimensional atomic distributions from the maximum entropy method and unexpectedly find a ring-like distribution of hydrogen in contrast to the commonly accepted discrete sites. In addition, total scattering analysis at 274 K clarified the difference in the intermolecular structure from ice VIII, the ordered counterpart of ice VII, despite an identical molecular geometry. Our complementary structure analyses robustly demonstrate the unique disordered structure of ice VII. Furthermore, these findings are related to proton dynamics, which drastically vary with pressure, and will contribute to an understanding of the structural origin of anomalous physical properties of ice VII under pressures. [ABSTRACT FROM AUTHOR]

To process ingots of FeGa alloy single crystals into wafers, Fe17% Ga alloy crystals were cut using multi-wire sawing or electric discharging and rolling. Further, their properties of magnetization and magnetostriction were analyzed using electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). It was observed that the magnetization and magnetostriction curves changed with increasing rolling reduction. Although magnetization was negligibly affected by deformation, the shape of the magnetostriction curve of the as-grown crystal could be modified by a slight reduction in rolling or a slight plastic deformation. EBSD results show that rolling introduced dislocations to form heterogeneous dislocation cell walls and decreased the surface roughness of the wafers. The pole figures obtained by XRD indicate that the samples were single crystals; however, the crystal orientation was different from the ideal orientation after rolling. Residual stress measurements using the cos ¡ method revealed that compressive and tensile stresses remained in the polycrystalline surface layers of the samples cut by multiwire sawing and electric discharging, respectively. Moreover, the stresses were affected by the tensile strains or magnetic fields when the residual stresses were relatively small in the sample. Although the magnetization and magnetostriction of a single crystal are affected by rolling, they are not significantly reduced by small rolling reductions. [ABSTRACT FROM AUTHOR]

Acquiring the quantitative state-of-charge (SOC) distribution of a lithium-ion battery cathode is important to improve the performance of lithium-ion batteries for the application to large-scale devices. The conventional method to obtain SOC distribution, i.e., X-ray absorption spectroscopy (XAS), requires a synchrotron radiation facility, references that are difficult to prepare, and an investigation of the XAS spectra of the references. Herein, we demonstrate that laser-induced breakdown spectroscopy (LIBS) can acquire a quantitative SOC of a charged lithium-ion battery cathode with high accuracy by comparing the SOC values of charged cathodes containing Li2NaV2(PO4)3 as an active material determined by LIBS, XAS, and a charge-discharge curve. We perform LIBS measurements in a reduced argon atmosphere of 1000 Pa and use a calibration curve obtained by measuring the emission intensities at 610.4 nm of the pristine cathode. The SOCs of the charged cathodes agree well with the average SOCs estimated from the charge-discharge curves, whereas those determined by XAS do not. Therefore, LIBS is more suitable to acquire a quantitative SOC distribution of a lithium-ion battery cathode than XAS because LIBS is a laboratory-scale measurement and requires a single simple reference in addition to its high accuracy. [ABSTRACT FROM AUTHOR]

Recent developments in the field of vibration-based power generators have highlighted the advantages of using Fe–Ga alloys; these are excellent-magnetostrictive materials having good mechanical properties, which makes them well suited for use as magnetostrictive elements. A rectangular Fe–Ga element oriented along the 〈100〉 direction in a U-shaped unimorph device produces a higher power generation efficiency than samples with other orientations such as 〈110〉 and 〈111〉. The crystal growth direction of the ingots and plane orientation of the elements have a minimal effect on the power-generation efficiency. The observations of the magnetic domain and elastic properties suggest that the anisotropy in power generation is attributable to the anisotropic magnetic and elastic properties of the Fe–Ga alloy. Thus, a high-performance, vibration-based power generator using the Fe–Ga alloy should be fabricated using elements with a 〈100〉 orientation, cut from a single-crystal Fe–Ga ingot. [ABSTRACT FROM AUTHOR]