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In situ gas-loading sample holders for two-dimensionally arranged detectors in time-of-flight neutron total scattering experiments have been developed to investigate atomic arrangements during deuterium absorption using time and real-space resolution. A single-crystal sapphire container was developed that allows conditions of 473 K and 10 MPa hydrogen gas pressure. High-resolution transient measurements detected deuterium absorption by palladium that proceeded within a few seconds. A double-layered container with thick- and thin-walled vanadium allowed conditions of 423 K and 10 MPa hydrogen gas pressure. The deuterium occupation sites of a lanthanum–nickel–aluminium alloy are discussed in detail on the basis of real-space high-resolution data obtained from in situ neutron scattering measurements and reverse Monte Carlo structural modeling.

YMgNi4-based alloys exhibit reversible hydrogen absorption and desorption reactions at near room temperature. Here, we report that Co-substituted YMgNi4-based alloys exhibited higher hydrogen contents and lower hydrogen absorption and desorption reaction pressures than unsubstituted alloys. The effects of Co-substitution viewed from atomic arrangements were particularly clarified by synchrotron radiation powder X-ray diffraction, neutron diffraction, and inelastic neutron scattering. Powder neutron diffraction of the Co-substituted alloy at 5 MPa of D-2 pressure suggested the formation of gamma-phase deuteride (higher deuterium content) from beta-phase deuteride (lower deuterium content). However, no gamma-phase deuteride was observed in the unsubstituted alloys at 5 MPa. Therefore, the gamma-phase deuteride formation of the Co-substituted alloy at lower pressure led to higher hydrogen contents than the unsubstituted alloys. The combined results of powder neutron diffraction and inelastic neutron scattering suggested that the gamma-phase hydride of the Co-substituted alloy was continuously generated due to additional H atoms at the H atom sites in the beta-phase hydride because of the disordered H atomic arrangement involving H-H interactions. As a result, hydrogen absorption and desorption reaction pressures for the gamma-phase deuteride formation with higher hydrogen storage capacity were lowered.

We report on the high-pressure synthesis, crystal structure, and magnetic properties of four novel transition-metal oxyhydrides─Ba

Scattering angle dependence has been experimentally examined for inelasticity effect on the intramolecular interference term observed from the time-of-flight neutron diffraction method. Internuclea...

Experimental evidence has been obtained for the structure-spectra relationship of hydrogen bonds in aqueous solutions. Intramolecular O-D distance, rOD, has been determined by the least-squares fitting analysis of the neutron interference term in the high-Q region observed for pure D2O and concentrated aqueous solutions. The average O-D stretching frequency, νOD, has been obtained from the position of the center of gravity of the observed ATR-IR O-D stretching band. The linear relationship between rOD and νOD has been confirmed in the liquid state. The slope of dνOD/drOD is evaluated to be -21 000 ± 1000 cm-1 A-1.

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X-ray photoelectron spectroscopy (XPS) is among the most powerful techniques to analyse structures of nitrogen-doped carbon materials. However, reported assignments of (1) graphitic nitrogen (N)/substitutional N, quaternary N (Q–N), or tertiary amine (T–N) and (2) pyrrolic N/secondary amine or T–N are questionable. Most reports assign peaks at ca. 401 eV as Q–N or graphitic N, whereas raw materials in most of those works contain neither counter anion nor halogen. Besides, the peak at ca. 400 eV has been assigned as pyrrolic N, but the presence of N–H is generally not confirmed. In this work, it was clarified that one of the reasons for the prevailing ambiguous assignments is the presence of N in heptagonal and pentagonal rings. The peaks at 400.1–401.2 eV were determined to be T–N, but not Q–N by analyzing graphitized polyimide (with the oxygen content of 0.01 at% or lower and the hydrogen content of 0 at%) using Raman spectroscopy, XPS, X-ray diffraction, total neutron scattering, elemental analysis, and molecular dynamics simulation. Besides, it was revealed that the peak at 400.1 eV originated from T–N on 5-membered rings or 7- and 5-membered rings, but not pyrrolic N because graphite including no hydrogen was used for analysis.

It has been reported that aqueous lithium ion batteries (ALIBs) can operate beyond the electrochemical window of water by using a superconcentrated electrolyte aqueous solution. The liquid structure, particularly the local structure of the Li+, which is rather different from conventional dilute solution, plays a crucial role in realizing the ALIB. To reveal the local structure around Li+, the superconcentrated LiTFSA (TFSA: bis(trifluoromethylsulfonil)amide) aqueous solutions were investigated by means of Raman spectroscopic experiments, high-energy X-ray total scattering measurements, and the neutron diffraction technique with different isotopic composition ratios of 6Li/7Li and H/D. The Li+ local structure changes with the increase of the LiTFSA concentration; the oligomer ([Lip(TFSA)q](p-q)+ (q > 2) forms at the molar fraction of LiTFSA (xLiTFSA) > 0.25. The average structure can be determined in which two water molecules and two oxygen atoms of TFSA anion(s) coordinate to the Li+ in the superconcentrated LiTFSA aqueous solution (LiTFSA)0.25(H2O)0.75. In addition, the intermolecular interaction between the neighboring water molecules was not found, and the hydrogen-bonded interaction in the solution should be significantly weak. According to the coordination number of the oxygen atom (TFSA or H2O), a variety of TFSA- and H2O coordination manners would exist in this solution; in particular, the oligomer is formed in which the monodentate TFSA cross-links Li+.

Anion-excess fluorite is a unique structure type of inorganic crystals and is well known as an appropriate crystal structure for fast anion conduction. In particular, the introduction of excess ani...

To achieve high-performance proton-exchange membranes (PEMs), understanding of the polymer structure/property relationship is crucial. In particular, the structure of water clusters (number, size, ...

Neutron diffraction measurements on 6Li/7Li isotopically substituted 10 and 33 mol % *LiTFSA (lithium bis(trifluoromethylsulfonyl)amide)-AN-d3 (acetonitrile-d3) and 10 and 33 mol % *LiTFSA-DMF-d7(N,N-dimethylformamide-d7) solutions have been carried out in order to obtain structural insights on the first solvation shell of Li+ in highly concentrated organic solutions. Structural parameters concerning the local structure around Li+ have been determined from the least squares fitting analysis of the first-order difference function derived from the difference between carefully normalized scattering cross sections observed for 6Li-enriched and natural abundance solutions. In 10 mol % LiTFSA-AN-d3 solution, 3.25 ± 0.04 AN molecules are coordinated to Li+ with a intermolecular Li+···N(AN) distance of 2.051 ± 0.007 A. It has been revealed that 1.67 ± 0.07 AN molecules and 2.00 ± 0.01 TFSA- are involved in the first solvation shell of Li+ in the 33 mol % LiTFSA-AN solution. The nearest neighbor Li+···NAN and Li+···OTFSA- distances are obtained to be r(Li+···N) = 2.09 ± 0.01 A and r(Li+···O) = 1.88 ± 0.01 A, respectively. The first solvation shell of Li+ in the 10 mol % LiTFSA-DMF-d7 solutions contains 3.4 ± 0.1 DMF molecules with an intermolecular Li+···ODMF distance of 1.95 ± 0.02 A. In highly concentrated 33 mol % LiTFSA-DMF-d7 solutions, there are 1.3 ± 0.2 DMF molecules and 3.2 ± 0.2 TFSA- in the first solvation shell of Li+ with intermolecular distances of r(Li+···ODMF) = 1.90 ± 0.02 A and r(Li+···OTFSA-) = 2.01 ± 0.01 A, respectively. The Li+···TFSA- contact ion pair stably exists in highly concentrated 33 mol % LiTFSA-AN and -DMF solutions.

The hydrogen storage properties and crystal structures of YMgNi4-based alloys, which were synthesized from (2 - x)YNi2 and xMgNi(2) (0.6

All-solid-state fluoride shuttle batteries (FSBs) present endless possibilities for next-generation rechargeable batteries. However, no standard choice for solid electrolytes and electrodes in FSBs...

Using a high-pressure synthesis method, we prepared the layered oxychalcogenide Ba2CoO2Ag2Te2 (space group: I4/mmm) with alternating stacks of CoO2 and Ag2Te2 layers, separated by Ba atoms. The CoO...

We present the high-pressure synthesis and crystal structure of a novel titanium hydride complex, BaCa2Ti2H14, with 9-fold coordination. It comprises a unique dinuclear [Ti2H14]6– complex that cons...

All-solid-state fluoride shuttle batteries (FSBs) have the potential to become the next generation of rechargeable batteries. However, there are gaps in the fundamentals of developing all-solid-sta...

Neutron diffraction, X-ray diffraction, and empirical potential structure refinement modeling were employed to study the structure of alkaline aqueous NaBD4 solutions at different NaBD4 concentrati...

We investigated the multiscale characters of the crystal structure of the oxynitride perovskite LaTiO2N. While X-ray diffraction results identified the average structure as being centrosymmetric, we detected a signature of unknown structural deformation. By viewing the local structure, we unveiled the formation of a polar structure at the nanoscale.

Among the various functionalities of hydrides, their use in hydrogen storage has been the most intensively studied because hydrides can store hydrogen compactly and safely. Thus, hydrides are key materials for the hydrogen economy. Here, the hydrogen storage material Al3FeH3.9 has been synthesized from cost-effective earth-abundant metals, Fe and Al. Hydrides consisting of Al and transition metals with low hydrogen affinities are rare because such alloys are unstable. However, it is expected that appropriate mixing of the chemical states of hydrogen atoms would allow synthesis of Al-Fe hydrides. The experimentally determined crystal structure of Al3FeD3.9 suggests realization of the mixing of the chemical state of hydrogen. Al3FeH3.9 is more thermodynamically stable than AlH3, and it is likely that the mixing of the chemical state of hydrogen atoms is the source of increased stability. The results of this study confirm that by controlling the chemical states of hydrogen, it is possible to tune the thermodynamic stability of hydrides and thus realize novel functional hydrides.

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.

In order to improve the reaction efficiency of fuel cells, the structure of carbon and ionomer affecting electronic and proton conduction and the distribution of voids affecting oxygen diffusion and drainage have been studied to find the guideline for the optimum structure of the catalyst layer. In this study we are developing a method to evaluate the dispersed structure of carbon and ionomer and the thickness of the ionomer layer by using the small and wide angle neutron scattering instrument, TAIKAN at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The dependence of ionomer-to-carbon weight ratio of small-angle neutron scattering (SANS) cross section of the solid carbon catalyst layer and the hollow carbon catalyst layer was evaluated comparatively. Furthermore, the relative humidity dependence of SANS cross section of the solid carbon catalyst layer and the hollow carbon catalyst layer was also evaluated by using the contrast variation method. This presentation is based on results obtained from a project, JPNP20003, subsidized by a New Energy and Industrial Technology Development Organization (NEDO).

Due to their accessible lattice oxygen redox (l-OR) at high voltages, Li-rich layered transition metal (TM) oxides have shown promising potential as candidate cathodes for high-energy-density Li-ion batteries. However, this l-OR process is also associated with unusual electrochemical issues such as voltage hysteresis and long-term voltage decay. The structure response mechanism to the l-OR behavior also remains unclear, hindering rational structure optimizations that would enable practical Li-rich cathodes. Here, this study reveals a strong coupling between l-OR and structure dynamic evolutions, as well as their effects on the electrochemical properties. Using the technique of neutron total scattering with pair distribution function analysis and small-angle neutron scattering, this study quantifies the local TM migration and formation of nanopores that accompany the l-OR. These experiments demonstrate the causal relationships among l-OR, the local/nanostructure evolutions, and the unusual electrochemistry. The TM migration triggered by the l-OR can change local oxygen coordination environments, which results in voltage hysteresis. Coupled with formed oxygen vacancies, it will accelerate the formation of nanopores, inducing a phase transition, and leading to irreversible capacity and long-cycling voltage fade.

It has been reported that aqueous lithium ion batteries (ALIBs) can operate beyond the electrochemical window of water by using a superconcentrated electrolyte aqueous solution. The liquid structure, particularly the local structure of the Li

Recently, SnSe has been found to possess a remarkable thermoelectric performance. As an isostructural compound to SnSe, SnS contains a more environmentally compatible and earth abundant element, which enables SnS a promising thermoelectric material for commercial application. In this work, we have performed systematic studies of the crystal structures and the lattice vibrations by means of neutron total scattering, Raman scattering measurements, and first-principle calculations. A structural transition has been observed by both temperature dependent neutron diffraction and pressure dependent Raman scattering. The lattice anharmonicity has been revealed by the local distortion induced by the Sn $5{s}^{2}$ lone pair and is also evidenced from the temperature dependent atomic displacement parameter of the Sn atom. By separating the intrinsic anharmonicity and lattice thermal expansion effects, we found that the former plays the primary role in the softening of the Raman active modes. Such anharmonicity has also been observed experimentally by the linewidth broadening of the high-energy optical modes and confirmed by frozen phonon calculations. Furthermore, our frozen phonon calculation reveals the presence of the quartic anharmonicity potential of those high-energy optical modes vibrating along the $b$ axis. Our data will contribute to a better understanding of the thermal conduction in SnS, which will be beneficial for the enhancement of the thermoelectric performance of this material.

A face-centered-cubic (FCC) YH3 phase is known to be stable only under high pressure (HP) of more than gigapascal order, and it reverts to the hexagonal YH3 ambient-pressure phase when the pressure is released. We previously found that the FCC YH3 can be stabilized even at ambient pressure by substituting Y for 10 mol % Li (LiH-stabilized YH3, LSY). The LSY was synthesized by heat treatment under gigapascal HP, but this process is unfavorable for mass production; that is, only a few tens of milligrams of a sample can be obtained in a single batch. In this study, we overcame this problem by applying a ball milling (BM) process for synthesizing the LSY phase, and the yield by the BM process reached on the order of grams. We confirmed that the structure of the BM sample was the same as that of the HP sample by X-ray diffractometry, Raman spectroscopy, and neutron total scattering pair distribution function analyses. The crystallinity of the BM sample, however, was lower than that of the HP sample. The difference in the crystallinity affects the thermal stability of the LSY. The BM sample with a lower crystallinity released hydrogen at a lower temperature. The BM sample was found to reversibly desorb/absorb hydrogen maintaining its initial FCC structure when the rehydrogenation temperature was at 423 K. However, when the rehydrogenation temperature of BM sample was more than 573 K, the FCC structure changed to the hexagonal ambient pressure phase due to thermal instability of FCC phase for the BM sample.