Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 225

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Local disorder in proton conductor BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ analyzed by neutron diffraction/ atomic pair distribution function

Igawa, Naoki; Kodama, Katsuaki; Taguchi, Tomitsugu*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Hoshikawa, Akinori*; Ishigaki, Toru*

Transactions of the Materials Research Society of Japan, 43(6), p.329 - 332, 2018/12

For the understanding of the crystal structural effect on the electrical properties, the local disorder in BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ which is one of the excellent proton conductors for solid oxide fuel cells was estimated by using the Atomic Pair Distribution Function (PDF) analysis method with the neutron diffraction. The local structure is almost the same as the average structure which was estimated by the Rietveld analysis using the cubic crystal structure (space group, $${it Pm}$$$$overline{3}$$$${it m}$$) in the atomic distance range of ${it r}$ $$>$$ 6${AA}$. The PDF profile was fitted better using the tetragonal crystal structure with the space group of ${it P}$4/${it mmm}$ than those with $${it Pm}$$$$overline{3}$$$${it m}$$ in the range ${it r}$ $$<$$ 6${AA}$. Those results indicate the presence of the local disorder in the lattice. In this work, the relationship between the average and local structures of BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ will be discussed.

Journal Articles

Strain measurement in Ti layers of CFRP/Ti laminates by synchrotron X-ray diffraction

Akita, Koichi; Nakatani, Hayato*; Ogihara, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Igawa, Naoki; Shimojo, Yutaka

SPring-8/SACLA Riyo Kenkyu Seikashu (Research Report) (Internet), 6(1), p.105 - 108, 2018/01

no abstracts in English

Journal Articles

Inter atomic force constants of $$beta$$-PbF$$_{2}$$ from diffuse neutron scattering measurement

Xianglian*; Bao, W.*; Guo, T.*; Li, P.*; Sakuma, Takashi*; Igawa, Naoki

International Journal of Innovation in Science and Mathematics, 5(6), p.165 - 167, 2017/11

Diffuse neutron scattering measurements were performed on powder $$beta$$-PbF$$_{2}$$ at 633 K. Oscillatory diffuse scattering intensities were observed and the observed diffuse scattering intensities were explained by including the correlation effects among thermal displacements of atoms. The force constants among first- and second-nearest-neighboring atoms in $$beta$$-PbF$$_{2}$$ calculated from the values of correlation effects and Debye-Waller temperature parameters were determined as 0.36 eV/ $AA $^{2}$$ at ${it r}$ = 2.599 ${AA}$ and 0.21 eV/ $AA $^{2}$$ at ${it r}$ = 3.001 AA, respectively.

Journal Articles

2016 Professional Engineer (PE) test preparation course; Nuclear and radiation technical disciplines

Takahashi, Naoki; Suzuki, Soju; Saito, Hiroto; Ueno, Takashi; Abe, Sadayoshi; Yamanaka, Atsushi; Tanigawa, Masafumi; Nakamura, Daishi; Sasaki, Shunichi; Mine, Tadaharu

Nippon Genshiryoku Gakkai Homu Peji (Internet), 20 Pages, 2017/05

no abstracts in English

Journal Articles

Feasibility study of technology for Pu solution monitoring including FP; Composition research of high active liquid waste and radiation measurement results on the surface of cell

Matsuki, Takuya; Masui, Kenji; Sekine, Megumi; Tanigawa, Masafumi; Yasuda, Takeshi; Tsutagi, Koichi; Ishiyama, Koichi; Nishida, Naoki; Horigome, Kazushi; Mukai, Yasunobu; et al.

Proceedings of INMM 57th Annual Meeting (Internet), 9 Pages, 2016/07

The International Atomic Energy Agency (IAEA) has proposed in its long-term research and development (R&D) plan, development of a real-time measurement technology to monitor and verify nuclear material movement continuously as part of an advanced approach to effectively and efficiently conduct safeguards for reprocessing facilities. Since the Tokai Reprocessing Plant (TRP) has solutions containing both Pu and fission products (FP), a new detector development project to monitor Pu with FP is being carried out from 2015 to 2017. This project is mainly conducted in the High Active Liquid Waste Storage (HALWS) in the TRP. For the first step of this project, as the confirmation of composition of high active liquid waste (HALW) to evaluate neutron/$$gamma$$-ray emitted from solution in the selected HALW tank which has the most amount of Pu in HALW tanks at the TRP, we took HALW sample and conducted $$gamma$$-ray spectrum measurement for HALW. As a study of detector setting location, to survey the available neutron/$$gamma$$-ray (i.e. intensity) at the outside surface of the cell where HALW tank is located, we implemented continuous measurement by neutron/$$gamma$$-ray detector. In this paper, we report three $$gamma$$-ray peaks related with $$^{238}$$Pu and $$^{239}$$Pu measured in the composition research of HALW, which is needed to identify Pu amount by the new detector that we are developing and the result of radiation measurement on the surface of the cell.

Journal Articles

Crystal structures and magnetic properties of nickel chain compounds PbM$$_2$$Ni$$_6$$Te$$_3$$O$$_{18}$$ (M = Mn, Cd)

Doi, Yoshihiro*; Suzuki, Ryo*; Hinatsu, Yukio*; Kodama, Katsuaki; Igawa, Naoki

Inorganic Chemistry, 54(22), p.10725 - 10731, 2015/11

 Times Cited Count:1 Percentile:93.54(Chemistry, Inorganic & Nuclear)

Journal Articles

Neutron diffraction study of 1D quantum spin system Li$$_{2}$$ZrCuO$$_{4}$$ with incommensurate magnetic structure

Yasui, Yukio*; Igawa, Naoki; Kakurai, Kazuhisa

JPS Conference Proceedings (Internet), 8, p.034012_1 - 034012_6, 2015/09

Magnetic structure has been studied by using neutron diffraction for quasi one-dimensional quantum spin system Li$$_{2}$$ZrCuO$$_{4}$$ with CuO$$_{2}$$ ribbon chains. The CuO$$_{2}$$ ribbon system Li$$_{2}$$ZrCuO$$_{4}$$ exhibits the antiferromagnetic transition at T$$_{N}$$ $$sim$$ 7 K, however, the magnetic transition is not accompanied with ferroelectricity. At 3K, we observed magnetic superlattice reflections at Q = (0, k, l$$pm$$$$delta$$) and (h, 0, l$$pm$$$$delta$$) (h, k and l = even) with $$delta$$$$sim$$ 0.488 by the powder neutron diffraction. By the combined studies of neutron diffraction and magnetization data, the magnetic structure of Li$$_{2}$$ZrCuO$$_{4}$$ is proposed. On the bases of the obtained data, reasons for absence of ferroelectricity in Li$$_{2}$$ZrCuO$$_{4}$$ are discussed.

Journal Articles

Local lattice distortion caused by short-range charge ordering in transition metal oxides

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*

JPS Conference Proceedings (Internet), 8, p.034002_1 - 034002_6, 2015/09

Journal Articles

Crystal structure and electron density distribution analyses of Nd$$_{x}$$Ce$$_{1-x}$$O$$_{2-delta}$$ for electrolyte by Rietveld/ maximum entropy method

Taguchi, Tomitsugu; Igawa, Naoki; Birumachi, Atsushi; Asaoka, Hidehito; Miwa, Shuhei; Osaka, Masahiko

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.339 - 342, 2015/06

Rare-earth doped ceria exhibits both ionic and electronic conductions, and those ceria with higher ratio of ionic conduction against electronic conduction is used as a solid electrolyte for solid oxide fuel cells. The electron density distributions in crystals are closely related to the electron diffusing pathway which affects the electronic conduction. In this study, we investigated the electron density distribution of doped ceria as a function of the content of Nd$$_{2}$$O$$_{3}$$-dopant to deduce the ratio of the electronic to ionic conduction. The crystal structure was refined with the space group, ${it Fm}$-3${it m}$, which is the same as undoped ceria. Ce and Nd ions randomly occupied the 4${it a}$ site and O ion the 8${it c}$ site. The electron conduction pathway was distributed through the 4${it a}$-8${it c}$ and 8${it c}$-8${it c}$ sites. The relationship between crystal structural change and electron density distribution as a function of the content of Nd$$_{2}$$O$$_{3}$$ dopant will be discussed.

Journal Articles

Study of annealing effect on crystal and local structures of doped zirconia using multi probe

Ito, Takanori*; Mori, Masashi*; Inukai, Manabu*; Nitani, Hiroaki*; Yamamoto, Takashi*; Miyanaga, Takashi*; Igawa, Naoki; Kitamura, Naoto*; Ishida, Naoya*; Idemoto, Yasushi*

Photon Factory News, 33(1), p.18 - 24, 2015/05

The effect of the annealing on the crystal and local structures of doped zirconia was investigated by multi-probe technique using synchrotron X-ray and neutron diffraction, and first principles calculation. It was revealed that the annealing process enhances the periodic distortion of some zirconia compounds by Rietveld/ maximum entropy methods applied to the SR-X-ray and neutron diffractions. In addition, the combined X-ray absorption spectroscopy and first-principles calculations results showed the ZrO$$_{8}$$ polyhedra in zirconia were distorted by the annealing. Those results indicate that the degradation of oxide ionic conductivity by the annealing was related to the periodic distortion in zirconia.

Journal Articles

Nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ analyzed by combination of Rietveld/ maximum entropy method

Igawa, Naoki; Kodama, Katsuaki; Birumachi, Atsushi; Taguchi, Tomitsugu

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.247 - 252, 2015/05

The nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ which is one of the primitive cathode materials for secondary Li-ion batteries, were analyzed by applying Rietveld refinement and MEM to neutron and X-ray diffraction data, to estimate the Li diffusing pathway. The crystal structure of LiMn$$_{2}$$O$$_{4}$$ could be refined with the space group, ${it Fd}$-3${it m}$ in the temperature range from 240 to 573 K. The structure was transformed to ${it Fddd}$ below 240 K. The isotropic thermal displacement parameter of Li was proportional to the temperature excluding 240 to 300 K. According to the MEM analyses it was indicated that the Li ions diffuse through 8${it b}$ and 16${it e}$ around 300 K.

Journal Articles

Inter-atomic force constants of BaF$$_{2}$$ by diffuse neutron scattering measurement

Sakuma, Takashi*; Makhsun*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Basar, K.*; Igawa, Naoki; Danilkin, S. A.*

AIP Conference Proceedings 1656, p.020002_1 - 020002_4, 2015/04

 Times Cited Count:1 Percentile:100

Diffuse neutron scattering measurement on BaF$$_{2}$$ crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF$$_{2}$$ was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. From the values of correlation effects and Debye-Waller temperature parameters, force constants among the first and second nearest neighboring atoms of BaF$$_{2}$$, were determined to be 4.40 and 2.30 eV/$AA$^{2}$$ at 295 K, respectively

Journal Articles

Effect of annealing on crystal and local structures of doped zirconia using experimental and computational methods

Ito, Takanori*; Mori, Masashi*; Inukai, Manabu*; Nitani, Hiroaki*; Yamamoto, Takashi*; Miyanaga, Takashi*; Igawa, Naoki; Kitamura, Naoto*; Ishida, Naoya*; Idemoto, Yasushi*

Journal of Physical Chemistry C, 119(16), p.8447 - 8458, 2015/04

 Times Cited Count:11 Percentile:51.66(Chemistry, Physical)

The effects of the annealing process on the crystal and local structures of the doped zirconia were investigated by Rietveld refinements of synchrotron X-ray and neutron diffraction, maximum entropy method (MEM), X-ray absorption spectroscopy (XAS) and first principles calculation (FPC). This study reveals that the crystal structures of the sintered and annealed ((Zr$$_{0.85}$$Y$$_{0.15}$$)O$$_{2}$$ and (Zr$$_{0.81}$$Sc$$_{0.18}$$Ce$$_{0.01}$$)O$$_{2}$$) are cubic with the space ${it Fm}$-3${it m}$ having large atomic displacement parameters (${it U}$). For the annealed (Zr$$_{0.85}$$Y$$_{0.15}$$)O$$_{2}$$, the ${it U}$ values reduce, and the electrons around the Zr/oxide ion sites gather at the center of each site. On the other hand, the annealed (Zr$$_{0.81}$$Sc$$_{0.18}$$Ce$$_{0.01}$$)O$$_{2}$$ shows the opposite tendency to that of the annealed (Zr$$_{0.85}$$Y$$_{0.15}$$)O$$_{2}$$.

Journal Articles

Estimation of force constants of Al from diffuse neutron scattering measurement

Makhsun*; Hashimoto, Takuya*; Sakuma, Takashi*; Takahashi, Haruyuki*; Kamishima, Osamu*; Igawa, Naoki; Danilkin, S. A.*

Journal of the Physical Society of Japan, 83(7), p.074602_1 - 074602_4, 2014/07

 Times Cited Count:2 Percentile:85.59(Physics, Multidisciplinary)

The correlations of atomic thermal displacements in Al were obtained from the analysis of diffuse neutron scattering intensity. The interatomic force constants were determined from the correlation effects using a newly introduced equation. The derived force constants and the crystal structure of Al were used to estimate the phonon dispersion relations, phonon density of states, and specific heat by computer simulation. The calculated phonon dispersion relations and specific heat of Al are similar to those obtained from inelastic neutron scattering and specific heat measurements, respectively.

Journal Articles

Local structural analysis by using atomic pair distribution function on mixed valence compound LiMn$$_2$$O$$_4$$

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*

JPS Conference Proceedings (Internet), 3, p.013012_1 - 013012_6, 2014/06

Journal Articles

Weak ferromagnetic ordering disordered by Rh$$^{3+}$$ ions for LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$

Asai, Shinichiro*; Okazaki, Ryuji*; Terasaki, Ichiro*; Yasui, Yukio*; Igawa, Naoki; Kakurai, Kazuhisa

JPS Conference Proceedings (Internet), 3, p.014034_1 - 014034_6, 2014/06

We have carried out the neutron scattering measurements for a single crystal of LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$ in order to investigate the ferromagnetic ordering induced by Rh$$^{3+}$$ substitution for Co$$^{3+}$$ of LaCoO$$_{3}$$. The ordered moment is evaluated to be 0.4$$pm$$0.2$$mu$$$$_{B}$$, which is consistent with the saturation magnetization of LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$. It indicates that the ferromagnetic ordering of LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$ originates from the short-range ferromagnetic ordering disordered by Rh$$^{3+}$$ ions.

Journal Articles

Crystal structural analysis of solid oxide fuel cells using the synchrotron X-ray and neutron diffraction method

Ito, Takanori*; Igawa, Naoki; Homma, Tetsuo*

Supuringu-8 No Kokido Hoshako O Riyoshita Gurin Enerugi Bunya Niokeru Denchi Kaihatsu, p.104 - 112, 2014/02

Functional materials consist of many elements and therefore have complex crystal structure. Synchrotron X-ray and neutron scattering facilities are powerful tools to investigate the crystal structural information of those materials. Here we make an introduction to the crystal analysis method by the synchrotron X-ray and neutron diffraction applying to the solid oxide fuel cells.

Journal Articles

Protonic conduction, crystal and electronic structures of La$$_{0.9}$$Ba$$_{1.1}$$Ga$$_{0.95}$$Mg$$_{0.05}$$O$$_{4-delta}$$

Hamao, Naoki*; Kitamura, Naoto*; Ito, Takanori*; Igawa, Naoki; Idemoto, Yasushi*; Daido, Hiroyuki; Kaku, Masanori*; Kubodera, Masakazu*

Solid State Ionics, 253, p.123 - 129, 2013/12

 Times Cited Count:3 Percentile:80.61(Chemistry, Physical)

La$$_{0.9}$$Ba$$_{1.1}$$Ga$$_{0.95}$$Mg$$_{0.05}$$O$$_{4-delta}$$ which is one of the candidates for solid electrolyte of solid oxide fuel cell was synthesized by means of a conventional solid-state reaction, and investigated by conductivity measurements, the Rietveld and maximum entropy method analyses using neutron and synchrotron X-ray diffraction data. Conductivity measurements indicated that simultaneous Ba and Mg substitutions for LaBaGaO$$_{4}$$ were effective way to improve the protonic conductivity. From the Rietveld and maximum entropy method analyses, it was confirmed that La$$_{0.9}$$Ba$$_{1.1}$$Ga$$_{0.95}$$Mg$$_{0.05}$$O$$_{4-delta}$$ kept the same crystal structure as LaBaGaO$$_{4}$$ even at elevated temperature, i.e. 1000 K, and that protons existed around the O3 site and formed hydrogen bonds. It is also found that oxygens in LaBaGaO$$_{4}$$-based samples formed Ga-O$$_{4}$$ tetrahedra, and the bonding strength was varied by the partial substitutions.

Journal Articles

Electrode properties of Li$$_{2}$$MnO$$_{3}$$ (${it C}$2/${it m}$) for a lithium-battery cathode in several charge-discharge potential ranges

Nakao, Yasuhiro*; Ozawa, Kiyoshi*; Fujii, Hiroki*; Mochiku, Takashi*; Iwai, Hideo*; Tsuchiya, Yoshinori*; Igawa, Naoki

Transactions of the Materials Research Society of Japan, 38(2), p.229 - 233, 2013/12

Li$$_{2}$$MnO$$_{3}$$ powder with a monoclinic cell related to the space group of ${it C}$2/${it m}$ was synthesized by a simplified coprecipitation method. Its electrode properties as a lithium-battery cathode were investigated in the charge-discharge potential ranges of 2.0 - 4.6, 2.0 - 4.8, and 2.0 - 5.0 V. In all the potential ranges, the electrochemical capacities gradually increased during cycling, and the increased capacities significantly depended on the potential ranges. Compared to the discharge capacities for the potential ranges of 2.0 - 4.6 and 2.0 - 5.0 V, the former merely increased from 12.5 to 22.5 mAhg$$^{-1}$$ between the 1st and 99th cycles, whereas the latter increased from 20.0 to 110.2 mAhg$$^{-1}$$ during the same cycling. The structural variation in Li$$_{2}$$MnO$$_{3}$$ is induced by the cycling, the rhombohedral phase is detected during cycling in the potential range of 2.0 - 5.0 V.

Journal Articles

Spin state of Co$$^{3+} $$ in LaCo$$_{1-x}$$ Rh$$_{x}$$O$$_{3}$$ investigated by structural phenomena

Asai, Shinichiro*; Okazaki, Ryuji*; Terasaki, Ichiro*; Yasui, Yukio*; Kobayashi, Wataru*; Nakao, Akiko*; Kobayashi, Kensuke*; Kumai, Reiji*; Nakao, Hironori*; Murakami, Yoichi*; et al.

Journal of the Physical Society of Japan, 82(11), p.114606_1 - 114606_6, 2013/11

 Times Cited Count:6 Percentile:50.55(Physics, Multidisciplinary)

Neutron and synchrotron X-ray diffraction for LaCo$$_{1-x}$$ Rh$$_{x}$$O$$_{3}$$ have been carried out in order to investigate the structural properties related with the spin state of Co$$^{3+}$$ ions. We have found that the values of the Co(Rh)-O bond lengths in the Co(Rh)O$$_{6}$$ octahedron of LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$ are nearly identical at 10 K. The lattice volume for the Rh$$^{3+}$$ substituted samples decreases with the thermal expansion coefficient similar to that of LaCoO$$_{3}$$ from room temperature, and ceases to decrease around 70 K. These experimental results favor a mixed state consisting of the high-spin state and low-spin state Co$$^{3+}$$ ions, and suggest that the high-spin state Co$$^{3+}$$ ions are thermally excited in addition to those pinned by the substituted Rh$$^{3+}$$ ions.

225 (Records 1-20 displayed on this page)