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Inelastic neutron scattering measurements on vitreous silica have revealed that the contribution from the acoustic-like mode along the position of the first sharp diffraction peak (FSDP) is prominent below the boson peak energy and at low temperatures. Strong coupling between this acoustic-like mode at the FSDP position and the boson peak has also been confirmed, which implies the existence of Ioffe-Regel limits in glasses. We propose that the origin of the excitations along the FSDP position can be attributed to the harmonic vibrations at the surface of void spaces in glasses. We also consider that the FSDP in glasses arises from a quasi-periodicity, which is caused by the continuity of void spaces, corresponding to the lattice spacing of crystalline counterparts.

The role of low-energy dynamics in vitreous silica is discussed from the viewpoint of atomic motion. Coherent inelastic neutron scattering measurements have given the averaged mean-square displacements through an evaluation of Debye-Waller factor. The temperature dependences of the averaged mean-square displacements have been obtained in various types of SiO 2 . The averaged mean-square displacements of vitreous silica are significantly greater than those of other SiO 2 samples at any temperatures. This finding is explained based on the distribution of double-well potentials, whose barriers are significantly small. The anisotropic and flexible atomic motions in vitreous silica should be realized for small barrier potentials, giving rise to an excess density of states around 5 meV. the so-called boson peak.

The neutron quasi-elastic scattering (QES) spectra for YbX (X = N, P, As) show a quite common feature independent of X. The Kondo effect almost completely suppresses the magnetic ordering, which indicates that T K is comparable to T RKKY of about 20 K. The crossover of QES spectra from a Gaussian-like to a Lorentzian-like form occurs with the increase of temperature.

Transition metal-metalloid amorphous systems such as Fe-B and Ni-B are usually applied for the soft magnetic metallic glassy alloys and are counted as one of prominent categories in the field of amorphous alloy technology. Since glass forming ability of these systems correlates closely with the atomic level structure depending on chemical species of metal and metalloid, the local structure analysis for these glassy alloys is strongly required. In order to obtain the reliable structural model for these metal (Fe, Ni)-metalloid (B) amorphous samples, we determined the partial structural functions by combinational use of neutron diffraction (ND) and anomalous X-ray scattering (AXS). The amorphous ribbon samples were produced by the single-roller melt-spinning technique. The AXS measurements at Fe and Ni absorption edges were carried out at BL-7C of Photon Factory, KEK. The ND experiment was performed by using the time-of-flight technique and high intensity total diffractometer, NOVA at MLF, J-PARC. The figure shows the g(r)s for Fe80B20, Ni81B19, and Ni60B40calculated by the interference functions obtained by ND measurements. The dashed lines in the figure indicate the interatomic distances estimated from Goldschmidt atomic radii (Fe: 1.28 Å, Ni: 1.25 Å, B: 0.97 Å). At the nearest neighbor region up to about 3 Å, the first peak could be accounted for a harmony of metal (M)–B and B–B pair correlations and the second peak is mainly contributed by the M-M pair correlation. As for the three dimensional structural modeling of the amorphous samples, reverse Monte Carlo simulation has been performed starting from an initial model of 2,000 atoms with the b.c.c. structure. The present simulation results are found to reproduce the experimental interference functions obtained by the ND, ordinary X-ray diffraction, and AXS measurements. We will present the obtained structural model and local structural units around B including their arrangement.

Reverse Monte Carlo modeling was carried out for Li7P3S11 metastable crystal and (Li2S)70(P2S5)30 glass based on time-of-flight neutron and synchrotron X-ray diffraction data. Polyhedral analysis of three-dimensional structures for Li7P3S11 metastable crystal and (Li2S)70(P2S5)30 glass were gave us not only structural characteristics but also structural origins related to their high ionic conductivity.

Zr63Ni25Al12 bulk metallic glass was investigated using neutron diffraction and anomalous x-ray scattering close to the Zr and Ni K edges. The experimental results were analyzed using reverse Monte Carlo modeling (RMC) to obtain partial structure factors and pair distribution functions. The obtained partial structural results were compared with RMC results when neutron diffraction data are not included in the analysis and the report of Zr60Ni25Al15 by Fukunaga et al. using high-energy x-ray and neutron total scattering data.

We report the current status of software development for chopper spectrometers at Materials and Life Science Facility (MLF), the Japan Proton Accelerator Research Complex (J-PARC). Our software, named “Utsusemi”, has already been utilized in actual users measurements, while we are proceeding with developments for more effective use of high flux neutrons and event-recording methods.

Studies of glass materials are motivated by revealing orders in disorder systems and observations of atomic structure in wide time-space region is essential. Such observation will reveal hierarchal structure, including nano-scale structure, and leads to find out the mechanism of glass transition behavior. At J-PARC, one ideal instrument will realize such observation but it is not so easy to realize the instrument. However, free and accurate combinations of several instruments will be powerful to approach the problems in disordered material.

In order to clarify local structure of 6H-type BaFeO3−δ, an atomic pair distribution function (PDF) was determined by neutron scattering experiments. Though Fe4+ concentration in BaFeO3−δ decreases below 170 K , the PDF pattern does not change at all temperatures. It indicates that the local structure around Fe ion dose not change in the decrease of Fe4+ concentration.

Electrical conductivity, time-of-flight neutron diffraction (TOF-ND), and synchrotron X-ray diffraction (SXRD) measurements were carried out for 7 Li 7 P 3 S 11 metastable crystal and ( 7 Li 2 S) 70 (P 2 S 5 ) 30 glass. Reverse Monte Carlo modeling based on the TOF-ND and SXRD data showed three-dimensional structures of 7 Li 7 P 3 S 11 metastable crystal and ( 7 Li 2 S) 70 (P 2 S 5 ) 30 glass. A detailed polyhedral analysis of the three-dimensional atomic configuration yielded the spatial distribution of [LiS 4 ] tetrahedra ([LiS 4 ] units) and S 4 tetrahedra (without Li + ion; [S 4 ] units) in 7 Li 7 P 3 S 11 metastable crystal and ( 7 Li 2 S) 70 (P 2 S 5 ) 30 glass. When an a c -[S 4 ] unit is recognized as a fully acceptable unit of the Li + ion, the coordination number of a c -[S 4 ] units around a [LiS 4 ] unit for 7 Li 7 P 3 S 11 metastable crystal was estimated to be 3.9 on average, whereas it was 1.9 for ( 7 Li 2 S) 70 (P 2 S 5 ) 30 glass. Such structural characteristics in 7 Li 7 P 3 S 11 metasta...

Synchrotron X-ray and neutron diffraction measurements were carried out for (7Li2S)x(P2S5)100?x glasses and a 7Li7P3Sn11 metastable crystal. The Reverse Monte Carlo (RMC) modeling provided us the three-dimensional structures of (7Li2S)x(P2S5)100?x and 7Li7P3S11, particularly the distribution of Li+ cations.

Hydrogen and deuterium pressure-composition (P-C) isotherm measurements were carried out for Ti0.31Cr0.49V0.20 bcc alloy. As a result, the residual hydrogen-to-metal ratio (H/M)res was almost the same as the residual deuterium-to-metal one (D/M)res; the (H/M)res and (D/M)res were approximately 0.5. Furthermore, the neutron scattering experiments were conducted with Ti0.31Cr0.49V0.20 alloys including the residual hydrogen and/or deuterium. It was found that H atoms absorbed in the first absorption cycle up to H/M = 0.5 are hardly bound in the desorption cycle as the residual hydrogen, whereas D atoms are mainly bound in Ti0.31Cr0.49V0.20 bcc alloy as the residual deuterium when D2 gas is partially used in the H absorption reaction.

A new technique of inelastic neutron scattering measurement utilizing the multiple incident energies is applied to the dynamical study of vitreous silica. A wide variety of extracted information from a series of two-dimensional maps of dynamical structure factor with multiple different incident energies are greatly valuable. The applicability and its expected contribution of new experimental technique into the further progress of scientific activities in solid state ionic materials are discussed. Received: 30 September 2010; Revised: 25 October 2010; Accepted: 26 October 2010

Gas desorption rates for several types of B(4)C resins were investigated using a throughput method. The investigation was particularly focused on determining the out gas composition, effects of dry air, grain size (density) effects on the gas desorption rates. It is found that water is the main component of out gas and that dry air can effectively reduce gas desorption.

Electrical conductivity, X-ray absorption near edge structure (XANES), and synchrotron X-ray diffraction (SXRD) measurements were carried out for (Li2S)x(P2S5)100-x glasses synthesized by a mechanical alloying (MA) technique. It was found that the electrical conductivity of (Li2S)x(P2S5)100-x suddenly increases by more than an order of magnitude in the x region between 25 and 30. Simultaneously, the XANES spectrum also changed drastically. In addition, the Reverse Monte Carlo (RMC) simulation gave us the detailed amorphous structures of (Li2S)20(P2S5)80 and (Li2S)40(P2S5)60, particularly a distribution of Li+ cations in a [PS4] tetrahedron-network was revealed for each sample.

X-ray powder diffraction (XRD) and small-angle neutron scattering (SANS) experiments were carried out for the hydrogenated and duterated Mg2Ni, respectively. According to the results of XRD experiments, both of them coexisted with unhydrogenated (or undeuterated) Mg2Ni in the hydrogen absorbing cycle. Furthermore, in the SANS experiments, a slope of SANS curve, I(Q), was roughly evaluated by using the following power law: I(Q) ∝ Q−m, where Q is the magnitude of the scattering vector, and m can be equated with a fractal dimensionality, DS (= 6 − m). In conclusion, the hydrogenated and duterated Mg2Ni showed DS~ 3 and ~ 2, respectively. The significant difference between DS's can be understood by considering the scattering length densities, ρ, of Mg2Ni, Mg2NiH4, and Mg2NiD4.

DAQ-Middleware is a software framework of network-distributed DAQ system based on Robot Technology Middleware, which is an international standard of Object Management Group (OMG) in Robotics and its implementation was developed by AIST. DAQ-Component is a software unit of DAQ-Middleware. Basic components have been already developed. For examples, Gatherer is a readout component, Logger is a data logging component, Monitor is an analysis component and Dispatcher, which is connected to Gatherer as input of data path and to Logger/Monitor as output of data path. DAQ operator is a special component, which controls those components by using the control/status path. The control/status path and data path as well as XML-based system configuration and XML/HTTP-based system interface are well defined in DAQ-Middleware framework. DAQ-Middleware was adopted by experiments at J-PARC while the commissioning at the first beam had been successfully carried out. The functionality of DAQ-Middleware and the status of DAQ-Middleware at J-PARC are presented.

To reveal hydrogen-metal interaction in metal hydride systems with high hydrogen density, we have constructed the high-pressure device for neutron diffraction at total scattering spectrometer NOVA in J-PARC. The device consists of the Paris-Edinburgh press, the alignment stages, the automatically regulated oil pump system and the temperature control system. By using this device, diffraction data are expected to be taken at pressures above 20 GPa over wide Q-range of 1-40A−1 with the resolution of ΔQ/Q~0.6 %, which enables us to determine hydrogen positions in high hydrogen-density materials in the real-space resolution of 0.16A.

The salt-induced phase separation was, for the first time, directly observed at a molecular level by small-angle neutron scattering (SANS) experiments performed at room temperature on acetonitrile–D2O and acetonitrile–D2O–NaCl mixtures as a function of acetonitrile mole fraction, XAN, and NaCl concentration, respectively. Aggregation or microheterogeneity in the acetonitrile–D2O mixtures was most enhanced at XAN = 0.3–0.4 with Debye correlation lengths LD ∼19 A. In the acetonitrile–D2O–NaCl mixtures at XAN = 0.2 the aggregation increased with NaCl content and reached a plateau of LD ∼20 A.

X-ray diffraction measurement was performed on an Mg50Ni50 amorphous alloy prepared by mechanical alloying under an Ar atmosphere. Reverse Monte Carlo (RMC) simulation based on the X-ray diffraction data was used to construct a three-dimensional atomic arrangement of the amorphous alloy. In addition, the local environments around the Mg and Ni atoms were investigated by using Voronoi polyhedral analysis on the RMC configuration. The results show that isosahedral structures are predominant around the Mg and Ni atoms in Mg50Ni50, although prismatic local structures are present around some of the Ni atoms.

Collective dynamics of metallic glass CuZr2 has been studied in the first pseudo Brillouin zone using high-resolution inelastic X-ray scattering. Acoustic-like longitudinal propagating excitations were observed and the dispersion relation was determined. In addition of longitudinal mode, transverse mode with half excitation energy contributes to medium energy-transfer region.

Structure and lithiation mechanism of the nongraphitizable carbon (hard carbon) fiber were determined by X-ray and neutron diffraction-pattern simulation, neutron small-angle scattering, and neutron total scattering techniques. The structure of the hard carbon is formed by two-dimensional graphene sheets, which are spaced by narrow interlayer space and slightly larger interlayer space, corresponding to the periodically layered region and the interlayer voids, respectively. The shape of these voids on the nanosize was characterized by a combination of ellipsoid and random branching form. The lithiation proceeded by two steps. At a shallow lithiation region, lithium intercalated into the periodically layered region and the interlayer spacing of this region expanded. At the deep lithiation stage, lithium was inserted into the interlayer nanovoid and the void size increased. The coordination numbers of the constituent ions indicated a two-dimensional graphene sheet in the whole structure; this supports the "wave" model for the hard carbon structure. Based on our X-ray and neutron scattering experiments, a new structure model and a lithiation mechanism are proposed.

We have carried out inelastic neutron scattering and total neutron scattering on the typical under-doped superconductor YBa2Cu3O6.6. We have found that the dynamical structure and the local structure showed anomalous behaviors at Tc (=57K) and well above Tc (∼150K), which may be explained by a spin-gap opening.

The crystal structure and phonon dynamics of the spin-Peierls material CuGeO 3 have been studied by neutron scattering. We found a large lattice anomaly in the a-b plane, perpendicular to the one-dimensional antiferromagnetic spin chain, above the transition temperature. The phonon modes at 100 meV, of the chain oxygens, show anomalous behavior, consistent with structural change. We therefore conclude that the structural evolution of the chain oxygens in the a-b plane, which mediates the spin-spin interaction along the c -axis, drives the spin-Peierls transition.

Inelastic neutron scattering studies were performed on a powder and assembly of single crystals of La1.85Sr0.15CuO4. Phonon density of states and the Q-dependence of dynamic structure factor as well as the details of phonon scattering function were investigated as a function of temperature. We found specific phonon modes at the Brillouin zone center and the zone boundary showed an anomalous behavior.

The second workshop on the future neutron source for Japan was held from September 12-13,1999 at KEK. Approximately 90 people were in attendance to hear a report on the present status of the project. After the last meeting, a formal agreement was made on March 18,1999 between KEK and JAERI to proceed jointly with the project. An international review committee reviewed the scientific case of the joint project in April 1999. Then a third party committee reviewed the project at the end of FY 1999 to address concerns regarding the impact the project will have on society and the effects to the national economy, as well as the scientific importance of it. According to this last review, the project should be approved by the government.

Density dependence of low-energy dynamics of vitreous silica was investigated by means of neutron scattering measurements. On densification, the intensity of the boson peak is drastically suppressed at the low-energy region, and eventually its position shifts toward higher energy. From this result we conclude that the origin of the boson peak is not a phonon scattering by local density fluctuations but a soft mode of void space in vitreous silica.

Mixing states for aqueous solutions of water-miscible organic solvents, acetonitrile and 1,4-dioxane, have been investigated at the molecular level by means of small-angle neutron scattering (SANS) and NMR relaxation. It has been shown that the organic solvent and water molecules are inhomogeneously mixed each other at the molecular level, although their mixtures are homogeneous at the macroscopic scale. Thus, both organic solvent clusters and water clusters coexist in the mixtures. The present investigation has also revealed that the microinhomogeneity of acetonitrile-water and 1,4-dioxane-water mixtures is gradually enhanced by cooling or adding salts toward phase separation. Based on the results, the effect of microinhomogeneity for solvent mixtures on chemical reactions was considered.

The dynamical structure factors S (Q, E) of SiO2 glass and of Ni67Zr33 metallic glass were measured by neutron inelastic scattering, over wide momentum hQ-energy E transfer range. The collective character of the excitations, that is whole dispersion relation, is observed for the first time in quasi-Brillouin zones, whose periodicity is defined by the static structure factor S (Q). The dispersions are quite analogous for both systems, but there are large differences. For SiO2 glass, it behaves like an acoustic dispersion, while it becomes optical with a broad feature at larger Q for Ni67Zr33 metallic glass. The difference may be attributed to the difference in the degrees of short-range order. We also confirmed that the dispersion coexists with the low-lying boson peak, strongly localized mode. We suggest a change in common lore, namely that a wave whose wavelength is shorter than the local density fluctuation, that is a high-energy acoustic phonon, cannot go beyond this region and dampens; this i...