A5041487572- Phase-change materials and chalcogenides
- Glass properties and applications
- Material Dynamics and Properties
- X-ray Diffraction in Crystallography
- Crystallography and Radiation Phenomena
- Chalcogenide Semiconductor Thin Films
- High-pressure geophysics and materials
- Crystal Structures and Properties
- Advanced X-ray Imaging Techniques
- Metallic Glasses and Amorphous Alloys
- Thermodynamic and Structural Properties of Metals and Alloys
- Crystallization and Solubility Studies
- Solid-state spectroscopy and crystallography
- Chemical Thermodynamics and Molecular Structure
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Electron Microscopy Techniques and Applications
- Spectroscopy and Quantum Chemical Studies
- Nuclear materials and radiation effects
- Topological Materials and Phenomena
- Advanced Chemical Physics Studies
- Theoretical and Computational Physics
- Nonlinear Optical Materials Studies
- Mineralogy and Gemology Studies
- Phase Equilibria and Thermodynamics
- Microstructure and mechanical properties
Kumamoto Industrial Research Institute
2021-2025
Kumamoto University
2016-2025
University of Shimane
2025
Shimane University
2025
Philipps University of Marburg
2012-2023
Kitasato University
2019-2020
Interface (United Kingdom)
2018
John Wiley & Sons (United States)
2018
Hiroshima City University
2016
Nagoya Institute of Technology
2016
The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga the Q range above 9 nm(-1) although is mostly described a hard-sphere liquid. An ab initio molecular dynamics simulation clearly supports this finding. From detailed analysis for S(Q,omega) spectra with good statistic quality, lifetime of 0.5 ps and propagating length 0.4-0.5 nm can be estimated phonon modes, which may correspond to size cages formed instantaneously Ga.
Transverse acoustic (TA) excitation modes were observed in inelastic x-ray scattering (IXS) spectra of liquid Sn. The energies and widths the TA are good agreement with results an ab initio molecular dynamics simulation. By comparing current correlation between experimental theoretical quantitatively, we have concluded that can be detected experimentally through quasi-TA branches longitudinal spectra. lifetime propagation length determined to ~0.7 ps 0.8-1.0 nm, respectively, corresponding...
Transverse acoustic (TA) excitation modes were observed in inelastic x-ray scattering spectra of liquid Fe, Cu and Zn. From the analysis current correlation functions, we concluded that TA can experimentally be detected through quasi-TA branches longitudinal these metals. The microscopic elastic constants are estimated a characteristic difference from macroscopic polycrystalline value was found Poisson's ratio which shows an extremely softer ∼0.38 compared with ∼0.275. lifetime determined to...
The measurements of the extended X-ray absorption fine structure and photoacoustic spectroscopy have been carried out for Se chains confined in channels synthetic mordenite with about 6.7 A diameter. first-nearest Se–Se distance is 2.32 A, shorter than that crystalline Se. edge adsorbed lies at wavelength amorphous This suggests covalent bonds along chain become stronger when coupling between adjacent reduced. It found isolated are strongly photo-sensitive.
Mn $K\ensuremath{\alpha}$ x-ray fluorescence holography (XFH) measurements were performed on a single crystal of ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}{\mathrm{Mn}}_{0.1}$ topological insulator at 100 and 300 K to search for the impurity sites atoms in this functional crystal. The three-dimensional atomic images reconstructed using an ${L}_{1}$-regularized linear regression. X-ray absorption fine-structure (XAFS) experiments also carried out 30--300 obtain additional structural information....
An energy-dispersive x-ray diffraction technique for fluid materials under high pressure, up to 2000 bar, and temperature, 1650 °C, has been developed using an source with energy 70 keV, a high-pressure vessel Be windows pressurized He gas, new sample cell made of single crystal sapphire. Using this one can overcome several difficulties intrinsic measurements fluids, such as vapor pressure absorption constant samples, scattering by cells, vessels. In order show excellent potential the...
In order to bridge experimental results for the atomic structure in mixed crystals between x-ray diffraction showing a Vegard's law and absorption fine spectroscopy indicating preservations of each Pauling's bond length, an fluorescence holography (XFH) experiment was carried out on ${\text{Zn}}_{0.4}{\text{Mn}}_{0.6}\text{Te}$ single crystal drawing three-dimensional image around Zn atom. The XFH intensities Te atoms with respect reference ZnTe are almost constant beyond five chemical bonds...
To evaluate local atomic structures around Co in high temperature diluted ferromagnetic semiconductor Co-doped TiO2, x-ray fluorescence holography and absorption fine structure experiments were carried out on rutile paramagnetic Ti0.99Co0.01O2 Ti0.95Co0.05O2 films. The atoms the simply substituted for Ti sites structure, whereas a suboxidic arrangement of CoO2Ti4 formed A theoretical investigation based series first-principles calculations indicated stability aggregated clusters supporting...
The local structures around Nb and Pb in the prototypical relaxor ferroelectric Pb(Mg${}_{1/3}$Nb${}_{2/3}$)O${}_{3}$ (PMN) were investigated by x-ray fluorescence holography. separate atomic images of nearest revealed acute obtuse rhombohedral crystal unit cells. Pb-Pb correlated showed a structure body-center-like $2{a}_{0}\ifmmode\times\else\texttimes\fi{}2{a}_{0}\ifmmode\times\else\texttimes\fi{}2{a}_{0}$ superlattice, proving rigid three-dimensional network structural model combining...
Atomic-resolution holography makes it possible to obtain the three-dimensional (3D) structure around a target atomic site. Translational symmetry of arrangement sample is not necessary, and 3D image can be measured when local site oriented. Therefore, structures such as dopants adsorbates are observable. Here, atomic-resolution comprising photoelectron holography, X-ray fluorescence neutron their inverse modes treated. Although measurement methods different, they handled with unified theory....
To clarify lattice distortions induced by adding Ga atoms in the InSb crystal, $K\ensuremath{\alpha}$ x-ray fluorescence holography (XFH) experiments were carried out on an In${}_{0.995}$Ga${}_{0.005}$Sb diluted mixed single and three-dimensional atomic images around reconstructed. Although are located almost at ideal positions of some differences can be observed for only first- second-neighboring atoms. By combining them with absorption fine structure data, large spatial fluctuations...
The structure of a ZnSnAs2 thin film epitaxially grown on an InP substrate was evaluated using x-ray fluorescence holography. reconstructed three-dimensional atomic images clearly show that the crystal is mainly sphalerite type, in contrast to bulk form. A large disordering As layers observed, whereas positions Zn/Sn atoms are relatively stable. analysis data indicates serve as buffer and relax strain caused by random occupation Zn Sn atoms. These results provide further understanding means...
Abstract The X‐ray diffraction measurements for fluid Se have been carried out in the temperature and pressure range up to 1500°C 815 bar. We developed a new type of high‐pressure vessel sample cell made single‐crystal sapphire using energy‐dispersive method. obtained structure factor pair distribution function as functions pressure. From detailed analysis we conclude that twofold coordinated is largely preserved region where optical gap disappears progressive increase conductivity becomes...
The dynamic structure factor $S(Q,\ensuremath{\omega})$ of liquid Fe was measured at $1570\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ near the melting point $1535\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ by using a high-resolution inelastic x-ray scattering (IXS). IXS spectra obtained show well-defined collective excitations, which is in contrast to predictions based on macroscopic thermodynamics. From detailed analysis both...
Anomalous x-ray scattering experiments on glassy Ge${}_{x}$Se${}_{1\ensuremath{-}x}$ were carried out at energies close to the Ge and Se $K$ absorption edges concentrations between $x=0.15$ $0.333$ in order explore correlation atomic structures short intermediate ranges stiffness transition which appears approximately $x=0.20$ this system. The partial structure factors ${S}_{ij}(Q)$ corresponding pair-distribution functions ${g}_{ij}(r)$ obtained using reverse Monte Carlo modeling. Although...
Local structures of ${\mathrm{Pd}}_{40}{\mathrm{Ni}}_{40}{\mathrm{P}}_{20}$ bulk metallic glass were investigated by combining anomalous x-ray scattering close to the Pd and Ni $K$ absorption edges, diffraction, neutron reverse Monte Carlo modeling, from which partial structure factors ${S}_{ij}(Q)$ pair distribution functions ${g}_{ij}(r)$ as well three-dimensional atomic configurations carefully obtained around constituent elements. A disagreement is found in local with an ab initio...
The energy-dispersive x-ray-diffraction measurements for expanded fluid Hg were carried out in the density region from 13.55 to 6.6 ${\mathrm{g}\mathrm{}\mathrm{cm}}^{\ensuremath{-}3}$ including metal-nonmetal $(M\ensuremath{-}\mathrm{NM})$ transition region. We developed a new type of high-pressure vessel and sample cell made single-crystal sapphire x-ray diffraction under high temperature pressure up 1530 \ifmmode^\circ\else\textdegree\fi{}C 1980 bars using method. obtained interference...
The authors have measured EXAFS spectra of liquid(1-)Se, Te, Se-Te mixtures and vapour (v-)Se for the first time. It is clearly observed that two-fold coordinated chain structure largely preserved in l-Se intrachain covalent bond contracts on melting. l-Te can be reproduced well by assuming a with shorter longer bonds within chain. In order to obtain partial structure-parameters liquid mixtures, are taken both Se Te K edges. Se-Se elongates increasing concentration. number Te-Te increases...
In this paper, we show experimentally that the sound velocity of nanometer wavelength exceeds millimeter for a Pd-based metallic glass completely frozen far below transition temperature. This indicates nanoscale elastically harder regions exist in matrix and, hence, softer are also present so as to realize macroscopic elasticity.
X-ray absorption fine structure (XAFS), x-ray fluorescence holography (XFH), and inelastic scattering (IXS) techniques were applied to an ${\mathrm{Fe}}_{2}({\mathrm{V}}_{0.95}{\mathrm{Ta}}_{0.05}$)Al Heusler-type thermoelectric material investigate the doping effect of Ta on local atomic dynamics. The XAFS XFH results show that positional correlation between surrounding Fe atoms is much more rigid than V Fe. In IXS results, we observed a broad dispersionless mode in energy range acoustic...