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Miyazaki, Yuzuru*; Igawa, Naoki; Yubuta, Kunio*
Acta Crystallographica Section B; Structural Science, Crystal Engineering and Materials (Internet), 77(3), p.371 - 377, 2021/06
Times Cited Count:0 Percentile:0.01(Chemistry, Multidisciplinary)Crystal structure of '(O'3)-type layered sodium cobalt oxide Na
CoO
(
0.78) was analyzed using the (3+1)-dimensional superspace approach to the neutron diffraction data. The crystal structure is described based on the superspace group
2 =
(
0
)00, wherein the positions of Na atoms are most significantly modulated in the monoclinic
-direction to form an ordered arrangement. Such a positional modulation causes a quasi-periodic shift of Na atoms from the centers of the NaO
polyhedra between undulated CoO
sheets, changing the form of the NaO
polyhedron from an octahedral coordination (O) to a trigonal prismatic one (P). Where the Na atoms are most significantly shifted, the neighboring Na atoms are located at almost touching distances and yielding Na-deficient sites. As a result, a typical sequence of NaO
octahedra with -O-O-O-P-
-P- along the a-axis is realized.
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 BaSnIn
O
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,
) in the atomic distance range of
6
. The PDF profile was fitted better using the tetragonal crystal structure with the space group of
4/
than those with
in the range
6
. 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
In
O
will be discussed.
Akita, Koichi; Nakatani, Hayato*; Ogihara, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Igawa, Naoki; Shimojo, Yutaka
SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 6(1), p.105 - 108, 2018/01
no abstracts in English
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 -PbF
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
-PbF
calculated from the values of correlation effects and Debye-Waller temperature parameters were determined as 0.36 eV/
at
= 2.599
and 0.21 eV/
at
= 3.001 AA, respectively.
Takahashi, Naoki; Suzuki, Soju; Saito, Hiroto; Ueno, Takashi; Abe, Sadayoshi; Yamanaka, Atsushi; Tanigawa, Masafumi; Nakamura, Daishi; Sasaki, Shunichi; Mine, Tadaharu
Nihon Genshiryoku Gakkai Homu Peji (Internet), 20 Pages, 2017/05
no abstracts in English
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/-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
-ray spectrum measurement for HALW. As a study of detector setting location, to survey the available neutron/
-ray (i.e. intensity) at the outside surface of the cell where HALW tank is located, we implemented continuous measurement by neutron/
-ray detector. In this paper, we report three
-ray peaks related with
Pu and
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.
Doi, Yoshihiro*; Suzuki, Ryo*; Hinatsu, Yukio*; Kodama, Katsuaki; Igawa, Naoki
Inorganic Chemistry, 54(22), p.10725 - 10731, 2015/11
Times Cited Count:7 Percentile:37.8(Chemistry, Inorganic & Nuclear)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 LiZrCuO
with CuO
ribbon chains. The CuO
ribbon system Li
ZrCuO
exhibits the antiferromagnetic transition at T
7 K, however, the magnetic transition is not accompanied with ferroelectricity. At 3K, we observed magnetic superlattice reflections at Q = (0, k, l
) and (h, 0, l
) (h, k and l = even) with
0.488 by the powder neutron diffraction. By the combined studies of neutron diffraction and magnetization data, the magnetic structure of Li
ZrCuO
is proposed. On the bases of the obtained data, reasons for absence of ferroelectricity in Li
ZrCuO
are discussed.
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
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 NdO
-dopant to deduce the ratio of the electronic to ionic conduction. The crystal structure was refined with the space group,
-3
, which is the same as undoped ceria. Ce and Nd ions randomly occupied the 4
site and O ion the 8
site. The electron conduction pathway was distributed through the 4
-8
and 8
-8
sites. The relationship between crystal structural change and electron density distribution as a function of the content of Nd
O
dopant will be discussed.
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 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.
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 LiMnO
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
O
could be refined with the space group,
-3
in the temperature range from 240 to 573 K. The structure was transformed to
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
and 16
around 300 K.
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:2 Percentile:65.08Diffuse neutron scattering measurement on BaF crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF
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
, were determined to be 4.40 and 2.30 eV/
at 295 K, respectively
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:15 Percentile:47.81(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 ((ZrY
)O
and (Zr
Sc
Ce
)O
) are cubic with the space
-3
having large atomic displacement parameters (
). For the annealed (Zr
Y
)O
, the
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
Sc
Ce
)O
shows the opposite tendency to that of the annealed (Zr
Y
)O
.
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:21.3(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.
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
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 LaCoRh
O
in order to investigate the ferromagnetic ordering induced by Rh
substitution for Co
of LaCoO
. The ordered moment is evaluated to be 0.4
0.2
, which is consistent with the saturation magnetization of LaCo
Rh
O
. It indicates that the ferromagnetic ordering of LaCo
Rh
O
originates from the short-range ferromagnetic ordering disordered by Rh
ions.
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.
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:16.26(Chemistry, Physical)LaBa
Ga
Mg
O
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
were effective way to improve the protonic conductivity. From the Rietveld and maximum entropy method analyses, it was confirmed that La
Ba
Ga
Mg
O
kept the same crystal structure as LaBaGaO
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
-based samples formed Ga-O
tetrahedra, and the bonding strength was varied by the partial substitutions.
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
LiMnO
powder with a monoclinic cell related to the space group of
2/
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
between the 1st and 99th cycles, whereas the latter increased from 20.0 to 110.2 mAhg
during the same cycling. The structural variation in Li
MnO
is induced by the cycling, the rhombohedral phase is detected during cycling in the potential range of 2.0 - 5.0 V.