Kyushu Synchrotron Light Research Center

Tosu, Japan

Kyushu Synchrotron Light Research Center

Tosu, Japan
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Okajima T.,Kyushu Synchrotron Light Research Center | Okajima T.,Kyushu University | Yasukawa K.,Kyocera Corporation | Umesaki N.,Japan Synchrotron Radiation Research Institute
Journal of Electron Spectroscopy and Related Phenomena | Year: 2010

The local environment of Ca dopants in barium titanate, BaTiO3, is investigated by Ca K-edge X-ray absorption near-edge structure (XANES) spectroscopy. In conjunction with experiments, first-principles calculations by two methods are systematically made. The projector-augmented wave (PAW) method is used to optimize the local structure and obtain the formation energy. The augmented plane wave plus local orbitalsmethodis adopted to obtain theoreticalXANESspectra.Acomparison between experimental and theoretical XANES spectra shows that Ca dopants are located at the Ba2+ sites forming Ca2+. Formation energy calculations of Ca doped BaTiO3 by the PAW method also give the same results. The Ca atom in BaTiO3 is off-centering in comparison with the Ba site in BaTiO3. The off-centering of Ca atom is newly revealed by the combination of XANES spectroscopy and first-principles DFT calculations. © 2010 Elsevier B.V. All rights reserved.

Han D.,Kyoto University | Uda T.,Kyoto University | Nose Y.,Kyoto University | Okajima T.,Kyushu Synchrotron Light Research Center | And 3 more authors.
Advanced Materials | Year: 2012

The existence of tetravalent dysprosium in perovskite-type oxide barium zirconate is confirmed in this work. This discovery will stimulate many researchers in diverse fields such as catalysts, solid state ionics, sensors, and fluorescent materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kobayashi E.,Kyushu Synchrotron Light Research Center | Okudaira K.K.,Chiba University | Okajima T.,Kyushu Synchrotron Light Research Center
Surface and Interface Analysis | Year: 2012

The effects of annealing on the molecular orientation in polytetrafluoroethylene (PTFE) thin films evaporated on copper and silicon plates were studied using F K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The intensity of the F 1 s → σ*(C-F) transition in the NEXAFS spectrum from a non-annealed PTFE thin film on a copper plate at a glancing X-ray incidence angle was stronger than that at the normal incidence angle. For a thin film annealed at ∼250 °C in a nitrogen atmosphere, the σ*(C-F) peak intensity at the glancing angle was weaker than that at a normal angle. The F K-edge NEXAFS spectra of a thin film annealed at ∼350 °C showed a weakening dependence on the X-ray incidence angle. This result indicates that the molecules in a PTFE thin film are increasingly oriented normal to the substrate surface with increasing annealing temperature and are oriented randomly. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

Mizukoshi Y.,Tohoku University | Okajima T.,Kyushu Synchrotron Light Research Center | Masahashi N.,Tohoku University
Applied Catalysis B: Environmental | Year: 2015

Anodization of Ti-6Al-4V alloy in acetic acid aqueous solution resulted in the formation of amorphous oxide on its surface; the amorphous oxide transformed into crystalline oxide primarily consisting of anatase TiO2 by annealing. The annealed anodic oxide, especially those anodized in 1-2molL-1 acetic acid aqueous solution, could photocatalytically decompose acetaldehyde under visible light illumination. X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray absorption near-edge structure spectroscopy analyses showed that the vanadium is pentavalent and exists in an oxygen-tetragonal structure composed of VO43- units. When the vanadate absorbs visible light, the excited electrons move into the conduction band of anatase TiO2 so that recombination with holes was restricted. As a result, the anodic oxide exhibited superior photocatalytic activity under visible light illumination. © 2014 Elsevier B.V.

Shigemasa E.,Japan Institute for Molecular Science | Kaneyasu T.,Japan Institute for Molecular Science | Kaneyasu T.,Kyushu Synchrotron Light Research Center | Matsushita T.,Japan Synchrotron Radiation Research Institute | And 3 more authors.
New Journal of Physics | Year: 2010

The autoionization of atomic fragments after core-to-Rydberg excitations in N2 has been studied using high-resolution electron spectroscopy. Doppler profiles are clearly observed on atomic autoionization peaks and show dependence on the symmetries of the excited states. It is demonstrated that information on the femtosecond dissociation dynamics after the Rydberg excitations can be gained through an analysis of the Doppler profiles. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Magome E.,Kyushu Synchrotron Light Research Center | Moriyoshi C.,Hiroshima University | Kuroiwa Y.,Hiroshima University | Masuno A.,University of Tokyo | Inoue H.,University of Tokyo
Japanese Journal of Applied Physics | Year: 2010

The crystal structure of metastable LuFeO3 synthesized by containerless processing has been revealed to be a non-centrosymmetric structure (space group P63cm) by analyzing the high-energy synchrotron-radiation powder-diffraction data using the maximum entropy method (MEM)/Rietveld method. The structural characteristics are found in the FeO 5 trigonal bipyramid distorted and tilted from the c-axis, which is cause by the hybridization of atomic orbitals between the O atom constituent of the polyhedron and the neighboring Lu atom. The spontaneous polarization expected from the polar structure is estimated at about 5μC/cm2. © 2010 The Japan Society of Applied Physics.

Yoneyama A.,Hitachi Ltd. | Baba R.,Hitachi Ltd. | Sumitani K.,Kyushu Synchrotron Light Research Center | Hirai Y.,Kyushu Synchrotron Light Research Center
Applied Physics Letters | Year: 2015

A high-spatial resolution X-ray computed tomography (CT) adopting a sub-pixel shift method has been developed. By calculating sectional images, using plural CT datasets obtained by scanning the X-ray imager, the spatial resolution can be reduced relative to the sub-pixel size of an X-ray imager. Feasibility observations of a biomedical sample were performed using 12-keV monochromatic synchrotron radiation and a photon-counting X-ray imager 174-μm pixels in size. Four CT measurements were performed to obtain datasets at different positions of the X-ray imager. Fine sectional images were obtained successfully, and the spatial resolution was estimated as 80-μm, which corresponds to just under half the pixel size of the imager. In addition, a fine 3D image was also obtained by scanning the imager two-dimensionally. © 2015 AIP Publishing LLC.

Ishiji K.,Kyushu Synchrotron Light Research Center | Kawado S.,Kyushu Synchrotron Light Research Center | Hirai Y.,Kyushu Synchrotron Light Research Center | Nagamachi S.,Nagamachi Science Laboratory Co.
Materials Science Forum | Year: 2016

The warpage structure of 4°-off-axis (0001) 4H-SiC samples after implantation and annealing processes was investigated using white light interferometry (WLI) and X-ray rocking curve (XRC) measurements. The WLI images showed that the surface warpage of the 300 °C-implanted/annealed SiC sample was small and almost the same as that of the un-implanted SiC sample, but the 30 and 150 °C-implanted/annealed SiC samples had a typically saddle-like warpage. The XRCs of the 0008-reflection were measured using monochromatic X-rays with different energies to change the X-ray penetration depth. The subtracted XRCs were reconstructed, and then the depth-dependence of the curvature radius of the 0008-reflection was evaluated. The results indicated that the saddle-like warpage of the 30 and 150 °C-implanted/annealed samples relaxed with increasing depth. © 2016 Trans Tech Publications, Switzerland.

Ishiji K.,Kyushu Synchrotron Light Research Center | Kawado S.,Kyushu Synchrotron Light Research Center | Hirai Y.,Kyushu Synchrotron Light Research Center
Physica Status Solidi (A) Applications and Materials Science | Year: 2011

We developed a compact synchrotron X-ray topography system equipped with a demountable Si channel-cut crystal monochromator with an energy range of 5-20keV at beamline 09A in SAGA Light Source (SAGA-LS) to enable switching between a white X-ray beam and a monochromatic X-ray beam. The position of incidence of the X-ray beam on the sample is kept constant because the beam-path difference, which is caused by inserting the monochromator and by tuning the X-ray energy, is adjusted automatically. Two possible applications of this system are proposed: (1) the observation of dislocations in a thick Si rod by white X-ray topography, and (2) a comparative study of X-ray images of defects and strain in a 4H-SiC wafer captured using white and monochromatic X-ray beams. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hirai Y.,Kyushu Synchrotron Light Research Center | Kamitsubo H.,Kyushu Synchrotron Light Research Center
Synchrotron Radiation News | Year: 2014

A progressive approach to industrial use of synchrotron radiation (SR) in Japan was initiated in the mid-1980s at the Photon Factory of KEK with the installation of the first dedicated beamlines by several leading electronic companies. Their original goals were to promote R&D of X-ray lithography technology as a candidate for next-generation lithography and to characterize semiconductor materials. Unfortunately, X-ray lithography has not been able to replace photolithography. On the other hand, discoveries of high-temperature superconductors, giant magneto-resistive materials, carbon nanotubes, fullerene compounds, etc., have given further impetus to the goal of utilizing SR in material characterization. Copyright Taylor & Francis.

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