Crystal and local structures of Pr2Co7Dx during its deuterium absorption process determined by neutron diffraction
Kenji Iwase; Yuhei Shitoh; Kazuhiro Mori, 筆頭著者
Inorganic Chemistry,, 2024年10月, ［査読有り］
Effect of Mn substitution on crystal structure and cyclic property of Y–Ni alloy with superlattice structure
Kenji Iwase; Reon Kunimoto; Ryuichi Katagiri; Kazuhiro Mori, 筆頭著者
Journal of Solid State Chemistry, 2024年01月, ［査読有り］
Crystal structure, microstructure, and mechanical properties of heat-treated oyster shells
Kenji Iwase; Yoshihito Harunari; Masayuki Teramoto; Kazuhiro Mori, 筆頭著者, Elsevier
Journal of the Mechanical Behavior of Biomedical Materials, 2023年09月10日, ［査読有り］
Crystal and local structures of La2Co7Hx obtained by synchrotron X-ray total scattering
Kenji Iwase; Takashi Ueno; Seiya Mashii; Hyunjeong Kim; Kouji Sakaki; Kazuhiro Mori, 筆頭著者, Elsevier
Journal of Alloys and Compounds, 2023年04月15日, ［査読有り］
Effects of Mixed Phases on Electrical Conductivities for (CeF3)1–m(CaF2)m Fast-Fluoride-Ion-Conducting Solid Electrolytes
Kazuhiro Mori; Shuki Torii; Kenji Iwase; Takeshi Abe; Toshiharu Fukunaga, ACS (American Chemical Society)
The Journal of Physical Chemistry C, 2023年01月30日, ［査読有り］
Phase transformation of hydride-phase Nd2Co7 with superlattice structure
Kenji Iwase; Yugo Honjyo; Kazuhiro Mori, 筆頭著者, Elsevier
Journal of Solid State Chemistry, 2022年10月01日, ［査読有り］
Crystal structure of deuteride phase of Nd-Ni alloy by X-ray and neutron diffraction
Kenji Iwase; Shuhei Ishida; Takashi Ueno; Kazuhiro Mori, 筆頭著者, Elsevier
Journal of Alloys and Compounds, 2022年08月30日, ［査読有り］
〔主要な業績〕Effect of Co substitution on hydrogenation behavior of GdNi3-xCox (x = 0, 0.2, 1.0) and crystal structure of its hydride phases
Kenji Iwase; Yuhei Shitou; Kazuhiro Mori, 筆頭著者
Int. J. Hydrogen Energy, 2022年01月20日, ［査読有り］
Hydrogenation characteristics of Ce2Ni7-type La2Co7 and its phase transformation during hydrogen absorption–desorption processes
Kenji Iwase; Seiya Mashii; Kazuhiro Mori, 責任著者, Elsevier
Journal of Solid State Chemistry, 2021年05月, ［査読有り］
Crystal structure of intermetallic compound Y5Co19 and its hydride phases
Kenji iwase; Kazuhiro Mori, 筆頭著者, Elsevier
International Journal of Hydrogen Energy, 2021年03月, ［査読有り］
Crystallographic hydride phase analysis and hydrogenation properties of Gd2Co7 with Ce2Ni7- and Er2Co7-type structures
Kenji Iwase; Shuhei Ishida; Kazuhiro Mori, 筆頭著者, Elsevier
International Journal of Hydrogen Energy, 2020年07月20日, ［査読有り］
Simultaneous broadening analysis of multiple Bragg edges observed by wavelength-resolved neutron transmission imaging of a deformed low-carbon ferritic steel
Hirotaka Sato; Kenji Iwase; Takashi Kamiyama; Yoshiaki Kiyanagi
ISIJ International, 2020年06月15日, ［査読有り］
Crystal structure, microhardness, and toughness of biomineral CaCO3
Kenji Iwase; Kazuhiro Mori, 筆頭著者, ACS
Crystal Growth & Design, 2020年04月01日, ［査読有り］
Structural and electrochemical features of (Li2S)x(SiS2)100–x superionic glasses
Kazuhiro Mori; Kenji Iwase; Yojiro Oba; Kazutaka Ikeda; Toshiya Otomo; Toshiharu Fukunaga
Solid State Ionics, 2019年11月01日, ［査読有り］
Crystal structure and hydrogen absorption- desorption property of La5Co19
Kenji Iwase; Takashi Ueno; Kazuhiro Mori
Int. J. Hydrogen Energy, 2019年09月01日, ［査読有り］
析出硬化系ステンレス鋼の冷間鍛造加工プロセスの開発
大貫啓人、和田正勝、五十嵐雅高、隠岐裕康、飛田厚、田代優、永野隆敏、岩瀬謙二、鈴木徹也
自動車技術会論文集, 2019年02月01日, ［査読有り］
Phase transition and hydrogenation properties of Ce2Ni7-type Pr2Co7 during hydrogen absorption process
Kenji Iwase; Kazuhiro Mori; Suguru Tashiro; Tetsuya Suzuki
Int. J. Hydrogen Energy, 2018年09月01日, ［査読有り］
Interstitial-atom-induced phase transformation upon hydrogenation in vanadium
Kouji Sakaki; Hyunjeong Kim; Kenji Iwase; Eric H. Majzoub; Akihiko Machida; Tetsuo Watanabe; Yumiko Nakamura
J. Alloys and Compd., 2018年08月01日, ［査読有り］
Effect of Mg substitution on crystalline structure and hydrogenation of Gd4MgNi19
Kenji Iwase; Kazuhiro Mori; Naoyoshi Terashita; Suguru Tashiro; Tetsuya Suzuki
Int. J. Hydrogen Energy, 2018年07月01日, ［査読有り］
Crystal Structure of Pr3MgNi14Dx Studied by in Situ Neutron DiffractionKenji Lwase; Kazuhiro Mori; Naoyoshi Terashita; Suguru Tashiro; Tetsuya Suzuki, The crystal structure of Pr3MgNi14D18 was determined by neutron diffraction. The determined structure of Pr3MgNi14D18 consisted of 89.0% Gd2Co7-type structure and 11.0% PuNi3-type structure. The lattice parameters of a and c of Gd2Co7-type structure were refined at 0.52903(7) nm and 3.90179(1) nm. The deuterium atoms were distributed among nine deuterium sites in both the CaCu5-type and MgZn2-type cells. The D-2 occupancy in the Pr2Ni4 octahedral sites of the CaCus-type cell was the largest (0.75) when compared with the other deuterium sites (<0.49). The deuterium content of the CaCus-type cell showed 0.75 DIM, but the D/M value of the MgZn2-type cell was 1.53. The volume expansions during deuteratiOn of the CaCus-type and MgZn2-type cells were nearly equal. The cyclic hydrogenation property of Pr3MgNi14 is comparable to that of LaNis. It is inferred that the similar expansion' ehavior of the CaCus-type and MgZn2-type cells during deuteration is the origin of this cyclic stability., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2017年06月,
［査読有り］ Structural origin of massive improvement in Li-ion conductivity on transition from (Li2S)(5)(GeS2)(P2S5) glass to Li10GeP2S12 crystalKazuhiro Mori; Takuya Kasai; Kenji Iwase; Fumika Fujisaki; Yohei Onodera; Toshiharu Fukunaga, We carried out synchrotron X-ray diffraction and time-of-flight neutron diffraction experiments for a lithium-ion conductor, (Li2S)(5)(GeS2)(P2S5) glass, prepared by mechanical alloying. The three-dimensional structure and the conduction pathways of Li ions in (Li2S)(5)(GeS2)(P2S5) glass were visualized by combining reverse Monte Carlo (RMC) modeling and the bond valence sum (BVS) approach. The electrochemical properties were characterized; the material demonstrated an electrical conductivity, sigma(300) (K), of 1.5 x 10(-5)S/cm at 300 I( and an activation energy, E-a, of 55 kJ/mol. In addition, it was found that the most advanced lithium-ion conductor, Li10GeP2S12 crystal (sigma(300K) = 1.2 x 10(-2) S/cm and E-a = 24 kJ/mot), could be obtained by aging the (Li2S)(5)(GeS2)(P2S5) glass at 803 K. By comparing the conduction pathways of Li ions in (Li2S)(5)(GeS2)(P2S5) glass with those in Li10GeP2S12 crystal, we found that vertical bar Delta V(Li)vertical bar(max), the maximum BV mismatch value for Li ions, for (Li2S)(5)(GeS2)(P2S5) glass (vertical bar Delta V(Li)vertical bar(max) = 0.13) was significantly larger than that for Li10GeP2S12 crystal vertical bar Delta V(Li)vertical bar(max) = 0.03). This indicates that the potential barrier, E-a, for Li ions moving along the conduction pathways lowers on the transition from (Li2S)(5)(GeS2)(P2S5) glass to Li10GeP2S12 crystal. Here, we propose that the lowering of the vertical bar Delta V(Li)vertical bar(max) is the reason for the structural origin of the massive improvement in sigma(300K) and E-a during the glass-to-crystal transition. (C) 2017 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
SOLID STATE IONICS, 2017年03月,
［査読有り］ Effect of Mg substitution on crystal structure and hydrogenation of Ce2Ni7-type Pr2Ni7
Kenji Iwase; Kazuhiro Mori; Naoyoshi Terashita; Suguru Tashiro; Tetsuya Suzuki
J. Solid State Chem, 2017年01月15日, ［査読有り］
Microstructural Information Mapping of a Plastic-deformed α-iron Plate during Tensile Tests using Pulsed Neutron TransmissionTakashi Kamiyama; Kenji Iwase; Hirotaka Sato; Stefanus Harjo; Takayoshi Ito; Shin Ichi Takata; Kazuya Aizawa; Yoshiaki Kiyanagi, © 2017 The Authors. The spatial-dependent lattice spacing and microstructure of an α-iron plate with two notches was measured during tensile tests using a pulsed neutron transmission method to ascertain changes depending on the load. Changes in microstructural parameters such as macrostrain, microstrain, crystallite size and texture are interesting during the transition from the elastic to plastic deformation region, especially over a relatively wide field of view to see propagation of the change. The method has the capability to show changes in the position-dependence of microstructural information simultaneously over a wide area in the bulk material. Transmission spectra around the Bragg-edge regions of the neutron total cross section of α-iron were obtained, and the microstructural parameters, {110} plane spacing and its distribution, texture coefficient and crystallite size were analyzed. The spatial-dependent distributions (images) of these parameters show sample shape effects including strain concentration around the notches and the effect of dislocations being multiplied during the plastic deformation. The spatial dependence of the microstructural parameters visualized herein provides useful information for evaluating the inhomogeneous progress of deformation of the bulk engineering material.
Physics Procedia, 2017年01月01日
Microstructural information mapping of a plastic-deformed -iron plate during tensile tests using pulsed neutron transmissionTakashi Kamiyama; Kenji Iwase; Hirotaka Sato; Stefanus Harjo; Takayoshi Ito; Shin-ichi Takata; Kazuya Aizawa; Yoshiaki Kiyanagi, The spatial-dependent lattice spacing and microstructure of an -iron plate with two notches was measured during tensile tests using a pulsed neutron transmission method to ascertain changes depending on the load. Changes in microstructural parameters such as macrostrain, microstrain, crystallite size and texture are interesting during the transition from the elastic to plastic deformation region, especially over a relatively wide field of view to see propagation of the change. The method has the capability to show changes in the position-dependence of microstructural information simultaneously over a wide area in the bulk material. Transmission spectra around the Bragg-edge regions of the neutron total cross section of alpha-iron were obtained, and the microstructural parameters, {110} plane spacing and its distribution, texture coefficient and crystallite size were analyzed. The spatial-dependent distributions (images) of these parameters show sample shape effects including strain concentration around the notches and the effect of dislocations being multiplied during the plastic deformation. The spatial dependence of the microstructural parameters visualized herein provides useful information for evaluating the inhomogeneous progress of deformation of the bulk engineering material. (C) 2017 The Authors. Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physics Procedia, 2017年,
［査読有り］ Synthesis of PuNi3-type PrCo3 and its hydrogen absorptiondesorption propertyKenji Iwase; Kazuhiro Mori; Shinnosuke Shimizu; Suguru Tashiro; Tetsuya Suzuki, We synthesized the intermetallic compound PrCo3 with the PuNi3-type structure. The structural parameters were refined by the Rietveld method. The refined lattice parameters were a = 0.5076(1) nm and c = 2.4831(6) nm. The pressure-composition (P-C) isotherm of PrCo3 was measured at 413 K. The maximum hydrogen capacity reached 0.95 H/M. Two plateaus were observed in the absorption-desorption process. The hydrogenation properties were reversible. The structure change of the hydride phase was investigated by X-ray diffraction. The space group of the full hydride phase (PrCo3H3.8) was determined to be R32; the metal sublattice of the original alloy (space group R-3m) transformed to R32 during the hydrogen absorption process. The volume expansions of the unit cell, and the CaCu5-type and MgZn2-type cells of the full hydride phase from the original alloy were 25.0%, 18.4%, and 22.7%, respectively. The structural change was accompanied by anisotropic lattice expansion. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Int. J. Hydrogen Energy, 2016年09月,
［査読有り］ Structural change of NdNi3 during hydrogen absorption-desorption cycleKenji Iwase; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki, The structural change of NdNi3 during the hydrogen absorption-desorption cycle and the P-C isotherm have been investigated. The maximum hydrogen capacity achieved in the first absorption process is 1.05 H/M. After the first desorption, 0.75 H/M of hydrogen capacity remains in the alloy. The trigonal crystal structure of the original alloy (R-3m) transforms to monoclinic (C2/m) in the first absorption. The crystal structure of the hydride phase remains monoclinic during the first desorption. The metal sublattice expands anisotropically during phase transformation from the alloy to the monoclinic hydride (NdNi3H4.0); a, b, and c axes expand by 8%, 7%, and 44%, respectively. The volumes of the unit cell, and the Nd2Ni4 and NdNi5 cells expand by more than 60%. Phase transformation of NdNi3H is irreversible during the first absorption-desorption cycle. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2016年02月,
［査読有り］ Effect of Mg substitution on hydrogen absorption-desorption behavior and crystal structure of Gd2-xMgxNi7Kenji Iwase; Naoyoshi Terashita; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki, The hydrogen absorption-desorption behavior and the crystal structure of Gd2-xMgxNi7 were investigated by pressure composition (PC) isotherm measurements and X-ray diffraction (XRD). Gd1.5Mg0.5Ni7 consists of two phases: 75% Gd2Co7-type structure and 25% PuNi3-type structure. Mg atoms substitute at the Gd site of the MgZn2-type cell in both Gd2Co7-type and PuNi3-type phases. In the hydrogen-free alloy after the PC isotherm measurement, the volumes of the (Gd/Mg)Ni-2 and GdNi5 cells of the Gd2Co7-type phase do not change appreciably, while those of the PuNi3-type phase experience shrinkage and expansion, respectively. A plateau region of Gcl(1.5)Mg(1.5)Ni(7) is observed between 0.06 H/M and 0.82 H/M. The reversible hydrogen content in the absorption desorption cycle is approximately 1.0 H/M. The enthalpy of hydride formation is evaluated as -24 kJ/mol H-2 from the Van't Hoff plot. The absorption desorption behavior is excellent even at low temperatures below 243 K. The hydrogen storage property of Gd1.5Mg1.5Ni7 is markedly improved by Mg substitution. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Int. J. Hydrogen Energy, 2016年,
［査読有り］ Crystal Structure Analysis of La2Ni6CoDx During Deuterium Absorption ProcessKenji Iwase; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki, The crystal structures of La2Ni6CoDx (x = 5.2 and 9.6) were determined by in situ neutron diffraction along the P-C isotherm. La2Ni6CoD5.2 (phase I) was found to be orthorhombic with lattice parameters a = 0.500670(2) nm, b = 0.867211(4) nm, and c = 2.99569(7) nm. The 10 deuterium sites were located in the MgZn2-type and CaCu5-type cells, with deuterium contents of 0.95 D/M and 0.39 D/M, respectively. The full deuteride La2Ni6CoD9.6 (phase II) was monoclinic with lattice parameters a = 0.516407(3) nm, b = 0.894496(6) nm, c = 3.11206(1) nm, and beta = 90.15(1)degrees. The phase II had 11 sites for deuterium occupation. The deuterium contents of the MgZn2-type and the CaCu5-type cell were 1.63 D/M and 0.78 D/M, respectively. The sequence of phase transformation of La2Ni6Co was hexagonal, followed by orthorhombic (phase I), and then monoclinic (phase II), for the first absorption process. The phase transformation resulted in lowered symmetry and the variation of deuterium atom occupation., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2015年09月,
［査読有り］ Imaging of texture, crystallite size and strain in materials using accelerator based pulsed neutron sources
Y. Kiyanagi; H. Sato; K. Iwase; T. Kamiyama
Proceedings of IAEA Technical Meeting on Utilization of Accelerator Based Real Time Methods in Investigation of Materials with High Technological Importance, 2015年, ［招待有り］
Local Structures and Bottleneck Size Distributions of Lithium Ion Conducting Oxides: Li3xLa2/3?xTiO3
Kazuhiro Mori; Kenji Iwase; Toshiharu Fukunaga
JPS Conf. Proc, 2015年, ［査読有り］
Three-dimensional structures and lithium-ion conduction pathways of (Li2S)x(GeS2)100-x superionic glassesKazuhiro Mori; Kozo Furuta; Yohei Onodera; Kenji Iwase; Toshiharu Fukunaga, The conduction pathways of Li ions in ((Li2S)-Li-7)(x)(GeS2)(100 - x) glasses (x = 40, 50, and 60) were predicted and visualized by combining reverse Monte Carlo (RMC) modeling and the bond valence sum (BVS) approach, using synchrotron X-ray and time-of-flight neutron diffraction data. The conduction pathways of the Li ions could be classified into four grades, according to the magnitude of vertical bar Delta V(Li)vertical bar:(I)vertical bar Delta V(Li)vertical bar <0.04 (i.e., relatively stable regions for the Li ions), (II) 0.04 <=vertical bar Delta V(Li)vertical bar <0.07, (III) 0.07 <=vertical bar Delta V(Li)vertical bar <0.10, and (IV) 0.10 <=vertical bar Delta V(Li)vertical bar <0.13; here, vertical bar Delta V(Li)vertical bar is the mismatch of the BVS for Li ions, V(Li). These were used to obtain a clear understanding of the movement of the Li ions in the ((Li2S)-Li-7)(x)(GeS2)(100 - x) glasses. It was also found that there is a definite relationship between the topology of the conduction pathways of the Li ions and the activation energy, E-a, of the electrical conduction. (C) 2015 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Solid State Ionics, 2015年,
［査読有り］ Visualization of conduction pathways in a lanthanum lithium titanate superionic conductor synthesized by rapid coolingKazuhiro Mori; Shogo Tomihi; Kenji Iwase; Toshiharu Fukunaga, Three-dimensional structure and conduction pathways of the lithium ions in (Li0.4La0.53TiO3)-Li-7 quenched with liquid nitrogen were studied using reverse Monte Carlo modeling and the bond valence sum approach using neutron diffraction data. The lithium ions were primarily located in the region between the off-center positions of the A-sites and bottlenecks defined by four coordinating oxygen ions. The bottlenecks in the predicted conduction pathways of the lithium ions were classified into three types (I, II, and III) by their size. The type II bottlenecks were the most accessible to lithium-ion migration and more than 70% of the bottlenecks were type II. (C) 2014 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Solid State Ionics, 2014年,
［査読有り］ Surface Observation of LaNi5 under Deuterium Atmosphere Using Small-Angle Neutron ScatteringKazuhiro Mori; Kenji Iwase; Yojiro Oba; Toshiharu Fukunaga; Masaaki Sugiyama, We developed a new sample holder for small-angle neutron scattering (SANS) experiments under controlled atmospheres. Using this new sample holder, SANS profiles of conventional hydrogen-absorbing alloy LaNi5 under a deuterium atmosphere were measured. Changes in the SANS profile of LaNi5 were clearly observed during absorption and desorption. It was found that there is reversibility in the surface morphology of LaNi5; it changed from being markedly rough (fractal dimension of particle surface D-S = 2.8, before deuteration) to smoother (D-S = 2.5 at 1.05 D/M, i.e., LaNi5D6.3) during absorption (up to 1 MPa), and then reverted to being rough (D-S = 2.8) during desorption (under vacuum <5 Pa), where D/M is the deuterium-to-metal ratio., JAPAN INST METALS
Mater. Trans., 2014年,
［査読有り］ Effects of Mg substitution on crystal structure and hydrogenation properties of Pr1-xMgxNi3Kenji Iwase; Naoyoshi Terashita; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki, The effects of substitution of Pr by Mg in PrNi3 with a PuNi3-type structure were investigated using pressure composition (P-C) isotherm measurements and X-ray diffraction. The unit cell of Pr0.68Mg0 Ni-32(3.04) contracted anisotropically in comparison to that of PrNi3. The maximum hydrogen capacity of PrNi3 reached 1.25 H/M in the first absorption. A plateau region was observed between 0.82 H/M and 1.04 H/M in the first absorption cycle. However, 0.85 H/M of hydrogen remained in the sample after the first full desorption. Pr0.68Mg0.32Ni3.04 showed reversible hydrogenation properties. The maximum hydrogen capacity was 1.22 H/M. The plateau region of Pr0.68Mg0.32Ni3.04 was between 0.08 H/M and 0.87 H/M, which was wider than that of PrNi3. Pr0.68Mg0.32Ni3.04 retained the PuNi3-type structure after hydrogenation, whereas the crystal structure of PrNi3 changed from that of PuNi3-type to an unknown structure. The structural change in PrNi3 during hydrogenation was evidently different from that in Pr0.68Mg0.32Ni3.04. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
International Journal of Hydrogen Energy, 2014年,
［査読有り］ Development of Energy-Selective Neutron Imaging
Yoshiaki Kiyanagi; Hirotaka Sato; Yoshinori Shiota; Takashi Kamiyma; Kenji Iwase; Shoji Uno
JPS Conf. Proc., 2014年, ［査読有り］
Neutron diffraction studies on structural effect for Ni-doping in LiCo1?xNixO2Dyah S. Adipranoto; Toru Ishigaki; Akinori Hoshikawa; Kenji Iwase; Masao Yonemura; Kazuhiro Mori; Takashi Kamiyama; Yukio Morii; Makoto Hayashi, We report structural effect for Ni-doping in lithium cobalt oxide (LiCoO2) studied by the time-of-flight (TOF) neutron powder diffractions measured at RT. Crystal and local structures of LiCo1 - xNiO2 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) powders, that were prepared by the solid-state reaction methods, have been respectively examined by using the IBARAKI Neutron Design Diffractometer (iMATERIA) of JPARC and Nanoscale-Ordered Material Diffractometer (NOMAD) of ORNL. The Rietveld refinement for neutron diffraction data of LiCo1 - xNixO2 that all have been indexed to the rhombohedral system with trigonal symmetry in the space group R-3m, revealed the lattice parameter c/a ratio that tends to the ideal value as decreasing Ni-contents, while the atomic pair distribution function (PDF) analysis for neutron data of LiCo1-xNixO2 revealed that the Co-O and the Ni-O pair correlation lengths under the first peak of G(r) that respectively vary from 1.88 to 1.9 angstrom and from 1.98 to 2.0 angstrom, with average Ni-O correlation length (1.99 angstrom) seems to be slightly larger than average Co-O correlation length (1.89 angstrom). Rather than that resulted by the Rietveld analysis, the PDF analysis suggested that the diffusion pathways between Co-O in the LiCo(1 - x)Ni(x)O2 system remain stable at similar to 1.89 angstrom for all Ni-contents. (C) 2013 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Solid State Ionics, 2014年,
［査読有り］ Crystal and local structure of lithium cobalt oxide studied by neutron diffraction
D. S. Adipranoto; T. Ishigaki; A. Hoshikawa; K. Iwase; H. Oguro; M. Yonemura; K. Mori; T. Kamiyama
Solid State Ionics: Ionics for Sustainable World, Proceedings of the Asian Conference 13th, 2013年, ［査読有り］
Crystal structure and hydrogen storage property of Nd2Ni7 superlattice alloy
Kenji Iwase; Kazuhiro Mori
Int. J. Hydrogen Energy, 2013年, ［査読有り］
Crystal Structure and Cyclic Hydrogenation Property of Pr4MgNi19Kenji Iwase; Naoyoshi Terashita; Kazuhiro Mori; Hitoshi Yokota; Tetsuya Suzuki, The hydrogen absorption-desorption property and the crystal structure of Pr4MgNi19 was investigated by pressure-composition isotherm measurement and X-ray diffraction (XRD). Pr4MgNi 19 consisted of two phases: 52.9% Ce5Co19-type structure (3R) and 47.0% Gd2Co7-type structure (3R). Sm5Co19-type structure (2H) and Ce2Ni 7-type structure (2H) were not observed in the XRD profile. The Mg atoms substituted at the Pr sites in a MgZn2-type cell. The maximum hydrogen capacity reached 1.14 H/M (1.6 mass%) at 2 MPa. The hysteresis factor, Hf = ln(Pabs/Pdes), was 1.50. The cyclic hydrogenation property of Pr4MgNi19 was investigated up to 1000 absorption-desorption cycles. After 250, 500, 750, and 1000 cycles, the retention rates of hydrogen were reduced to 94%, 92%, 91%, and 90%, respectively. These properties were superior to those of Pr2MgNi 9 and Pr3MgNi14. © 2013 American Chemical Society.
Inorg. Chem., 2013年,
［査読有り］ Visualization of conduction pathways in lithium superionic conductors: Li2S-P2S5 glasses and Li7P3S11 glass-ceramicKazuhiro Mori; Tomoharu Ichida; Kenji Iwase; Toshiya Otomo; Shinji Kohara; Hajime Arai; Yoshiharu Uchimoto; Zempachi Ogumi; Yohei Onodera; Toshiharu Fukunaga, For (Li2S)(x)(P2S5)(100-x) glasses and Li7P3S11 glass-ceramic, which are well-known lithium superionic conductors, the conduction pathways of lithium ions were predicted and visualized by combining reverse Monte Carlo (RMC) modeling and the bond valence sum (BVS) method using synchrotron X-ray and time-of-flight neutron diffraction data. The conduction pathways of the lithium ions could be classified into two types: lithium 'stable' and 'metastable' regions. In addition, it was found that a significant relationship exists between the topology of the conduction pathways of the lithium ions and the activation energy of the electrical conduction. (C) 2013 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE BV
Chemical Physics Letters, 2013年,
［査読有り］ In situ XRD Study of La2Ni7Hx during Hydrogen Absorption-DesorptionKenji Iwase; Kouji Sakaki; Yumiko Nakamura and Etsuo Akiba, Structural changes of La2Ni7H, during the first and second absorption desorption processes along the P C isotherm were investigated by in situ X-ray diffraction (XRD). Orthorhombic (Pbcn) and monoclinic (C2/c) hydrides coexisted in the first absorption plateau,. but only a monoclinic (C2/c) hydride was observed in the first desorption plateau. Phase transformation of La2Ni7Hx was irreversible. between the first as well as the second absorption desorption, process.. The lattice parameters and expansion of La2Ni4 and LaNis cells during the-absorption-7desorptiowproCess were refined using the Rictveld method. The lattice parameter's a and b ofthe.orthorhornbic hydride (Pbcn) decreased, while the lattice, parameter c. increased : with. increasing' hydrogen content in the first absorption. During the first absorption, the volume of the orthorhombic La2Ni4 cell expanded by more than 50%, while the expansion of the LaNis cell was below 10%: The monoclinic La2Ni4 cell expanded to approximately four times the size of the LaNis cell in the first absorption. The lattice parameters a, b, and c of the ;monoclinic hydride (C2/c). decreased with decreasing hydrogen content in the first. desorption contracted isotropically in the first desorption. These La2Ni4 and LaNis cells, AMER CHEMICAL SOC
Inorg. Chem, 2013年,
［査読有り］ Small-angle neutron scattering observation of the surface structure of Ti0.31Cr0.33V0.36 alloy in hydrogenationKazuhiro Mori; Kenji Iwase; Yasutaka Nishikawa; Masaaki Sugiyama; Yojiro Oba; Toshiharu Fukunaga, The surface structure of Ti0.31Cr0.33V0.36, which is an excellent hydrogen absorbing alloy, was directly observed in the first absorption-desorption cycle of hydrogen by small-angle neutron scattering (SANS). In addition, characterizations by pressure-composition isotherm (P-C-T) measurements and X-ray diffraction (XRD) were also carried out. The results of these experiments revealed the relationship between the slope of a SANS profile (alpha) and the hydrogen content (H/M). We suggest that the variation of alpha with H/M can be understood by considering the volume expansion of the surface during hydrogenation, which may exercise a significant role in the change from rough to smooth surface. (C) 2013 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
J. Alloys Compd, 2013年,
［査読有り］ Upgrade of Bragg edge analysis techniques of the RITS code for crystalline structural information imaging
H.Sato; T. Shinohara; R. Kiyanagi; K. Aizawa; M. Ooi; M. Harada; K. Oikawa; F. Maekawa; K. Iwase; T. Kamiyama; Y. Kiyanagi
Physics Procedia, 2012年, ［査読有り］
Recent progress of pulsed neutron imaging in Japan
Y. Kiyanagi; H. Sato; K. Iwase; T. Kamiyama
Physics Procedia, 2012年, ［査読有り］
Structural parameters of Pr3MgNi14 during hydrogen absorption-desorption processK. Iwase; N. Terashita; K. Mori; T. Ishigaki, Structural parameters of Pr3MgNi14 after a cyclic hydrogen absorption-desorption process were investigated by X-ray diffraction. Pr3MgNi14 consisted of two phases: 80% Gd2Co7-type structure and 20% PuNi3-type structure. The pressure-composition (P-C) isotherm of Pr3MgNi14 indicates a maximum hydrogen capacity of 1.12 H/M (1.61 mass %) at 298 K. The cyclic property of Pr3MgNi14 up to 1000 cycles was measured at 313 K. The retention rate of the sample was 87.5% at 1000 cycles, which compares favorably with that of LaNi5. After 1000 cycles, the expansions of lattice parameters a and c and the lengths along the c-axes of the PrNi5 and PrMgNi4 cells of the Gd2Co7-type structures were 0.20%, 1.26%, 0.47%, and 3.68%, respectively. The metal sublattice expanded anisotropically after the cyclic test. The isotropic and anisotropic lattice strains can be refined by Rietveld analysis. The anisotropic and isotropic lattice strains were almost saturated at the first activation process and reached values of 0.2% and 0.1%, respectively, after 1000 cycles. These values are smaller by 1 order of magnitude than those of LaNi5., AMER CHEMICAL SOC
Inorg. Chem., 2012年,
［査読有り］ Crystal structure and cyclic properties of hydrogen absorption?desorption in Pr2MgNi9K. Iwase; N. Terashita; K. Mori; S. Tsunokake; T. Ishigaki, We investigated the crystal structure and cyclic hydrogen absorption-desorption properties of Pr2MgNi9. The structural model is based on the PuNi3-type structure; the Mg atom is assumed to substitute for the Pr site in an MgZn2-type cell. The refined lattice parameters were determined from X-ray diffraction. A wide plateau region was observed in the P-C (pressure composition) isotherm at 298 K. The maximum hydrogen capacity reached 1.12 HIM (1.62 mass%) under a hydrogen pressure of 2.0 MPa. After 1000 hydrogen absorption-desorption cycles, the hydrogen capacity was superior to that of LaNi5 (82%). Anisotropic lattice strain occurred in the hydriding process. The anisotropic peak-broadening vector was determined to be < 001 >. The calculated anisotropic lattice strains of the initial cycle and after 1000 cycles were far smaller than those of LaNi5. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Int. J. Hydrogen Energy, 2012年,
［査読有り］ Direct observation of supercooled water in mortar materials by quasi-elastic neutron scatteringK. Mori; K. Iwase; M. Sugiyama; T. Fukunaga; O. Yamamuro, In order to clarify the mechanism of frost damage for concrete materials, we investigated the state of water in a Low Heat Portland Cement (LHPC) mortar at temperatures between
T = 282 K and 202 K, using quasi-elastic neutron scattering (QENS). Below the freezing point of water (i.e.,
T ＜ 273 K), a broad peak for supercooled water in the LHPC mortar was clearly observed on a QENS spectrum. In addition, the supercooled water index (
SCWI), which is the ratio of the signal from the supercooled water (
SCW) to the signal from the free water at 282 K (
FW282K) (i.e.,
SCWI =
SCW /
FW282K), was estimated for each temperature in a freeze-thaw cycle. Consequently, it was found that there is a hysteresis in the
SCWI(
T) curve; the amount of the supercooled water in the freeze cycle was 1.2-1.4 times larger than that in the thaw cycle at the same temperature., The Materials Research Society of Japan
Trans. Mater. Res. Soc. Jpn,, 2012年,
［査読有り］ Crystal structure of GdNi3 with superlattice alloy and its hydrogen absorption-desorption propertyK. Iwase; K. Mori; A. Hoshikawa; T. Ishigaki, We synthesized the intermetallic compound GdNi3, which has a PuNi3-type structure (space group R-3m), and investigated its P-C isotherm. The refined lattice parameters were a = 0.4993(1) nm and c = 2.4536(4) nm. In the first absorption process, two plateaus were observed, and the maximum hydrogen capacity reached 1.07 H/M. In the first desorption process, a narrow and sloping plateau was observed at approximately 0.02 MPa. After the first full desorption, 0.6 H/M of hydrogen remained in the sample. This sample showed severe peak broadening in the XRD pattern, indicating that the metal sublattice deformed from the original alloy. No plateau region was observed in the second absorption-desorption cycle. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Int. J. Hydrogen Energy, 2012年,
［査読有り］ Neutron scattering studies of Ti-Cr-V bcc alloy with the residual hydrogen and deuteriumKazuhiro Mori; Kenji Iwase; Masaaki Sugiyama; Maiko Kofu; Osamu Yamamuro; Youhei Onodera; Toshiya Otomo; Toshiharu Fukunaga, 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 D-2 gas is partially used in the H absorption reaction., IOP PUBLISHING LTD
J. Phys, 2012年,
［査読有り］ In situ lattice strain mapping during tensile loading using the neutron transmission and diffraction methodKenji Iwase; Hirotaka Sato; Stefanus Harjo; Takashi Kamiyama; Takayoshi Ito; Schinichi Takata; Kazuya Aizawa; Yoshiaki Kiyanagi, In this study, the change in internal lattice strain in an iron plate during tensile deformation was investigated by performing in situ measurements under applied force. The lattice strain was evaluated by neutron diffraction and Bragg-edge transmission. The neutron diffraction results showed that the averaged 110 lattice strain along the direction perpendicular to the applied force was between -422 and -109 x 10(-6). The position dependence of the lattice strain and the change in the distribution of elastic strain in an iron plate with notches during tensile deformation was obtained by Bragg-edge transmission. It was also observed that, when the load increased over 30 kN, the area of plastic deformation increased around the positions of the notches., WILEY-BLACKWELL
J. Appl. Cryst, 2012年,
［査読有り］ Hydrogenation and structural properties of Gd2Ni7 with superlattice structureKenji Iwase; Kazuhiro Mori; Akinori Hoshikawa; Toru Ishigaki, The crystal structure and hydrogenation properties of Ce2Ni7-type Gd2Ni7 were investigated by X-ray diffraction (XRD) and the hydrogen pressure composition (P C) isotherm. Ce2Ni7-type Gd2Ni7 was obtained by annealing at 1523 K for 12 h and quenching in ice water. Two superlattice reflections (002 and 004) of the Ce2Ni7-type were dearly observed at 2 theta = 7.3 degrees and 14.6 degrees in the XRD profile. The refined lattice parameters were a = 0.49662(9) nm and c = 2.4255(3) nm, respectively. Two plateaus were clearly observed during the absorption-desorption process in the P C isotherm. The first and second plateaus were at 0.015 and 0.13 MPa, respectively, in the first desorption. The maximum hydrogen capacity reached was 1.13 HIM. The enthalpy and entropy were calculated as -20 kJ/mol H-2 and -80 J/mol H-2 K, respectively, from the van't Hoff plot. After the P-C isotherm, the GdNi5 cell expanded by 2.15%, but the Gd2Ni4 cell shrank by 2.83%. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Int. J. Hydrogen Energy, 2012年
Pulsed neutron spectroscopic imaging for crystallographic texture and microstructureHirotaka Sato; Takashi Kamiyama; Kenji Iwase; Toru Ishigaki; Yoshiaki Kiyanagi, A time-of-flight (TOF) spectroscopic neutron imaging at a pulsed neutron source is expected to be a new material analysis tool because this method can non-destructively investigate the spatial dependence of the crystallographic and metallographic information in a bulk material. For quantitative evaluation of such information, a spectral analysis code for the transmission data is necessary. Therefore, we have developed a Rietveld-like analysis code, RITS. Furthermore, we have applied the RITS code to evaluation of the position dependence of the crystal orientation anisotropy, the preferred orientation and the crystallite size of a welded a-iron plate, and we successfully obtained the information on the texture and the microstructure. However, the reliability of the values given by the RITS code has not been evaluated yet in detail. For this reason, we compared the parameters provided by the RITS code with the parameters obtained by the neutron TOF powder diffractometry and its Rietveld analysis. Both the RITS code and the Rietveld analysis software indicated values close to each other, but there were systematic differences on the preferred orientation and the crystallite size. (C) 2011 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 2011年09月,
［査読有り］ Pulsed neutron spectroscopic imaging for crystallographic texture and microstructure
H. Sato; T. Kamiyama; K. Iwase; T. Ishigaki; Y. Kiyanagi
Nucl. Instrum. Methods A, 2011年01月25日, ［査読有り］
Synthesis of new compound Gd5Ni19 with superlattice structure and hydrogen absorption propertyKenji Iwase; Kazuhiro Mori; Akinori Hoshikawa; Toru Ishigaki, We successfully synthesized the new intermetallic compound Gd5Ni19 and determined its crystal structure by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The structure is a Sm5Co19-type superlattice structure (2H, space group P6(3)/mmc), and the lattice parameters were determined as a = 0.4950(1) nm and c = 3.2161(5) run by X-ray Rietveld refinement. The XRD results agreed with the STEM analysis results. The P-C isotherm of Gd5Ni19 was measured at 233 K. In the first absorption cycle, the maximum hydrogen capacity reached 1.07 H/M at 2.0 MPa. The sloping plateau was observed in the first absorption-desorption cycle. The maximum hydrogen capacity decreased by 0.87 H/M in the second absorption cycle, implying that hydrogen in the amount of H/M = 0.20 remained in the alloy before the second absorption - desorption cycle., AMER CHEMICAL SOC
Inorg. Chem, 2011年,
［査読有り］ Synthesis and crystal structure of a Pr5Ni19 superlattice alloy and its hydrogen absorption-desorption propertyK. Iwase; K. Sakaki; J. Matsuda; Y. Nakamura; T. Ishigaki; E. Akiba, The intermetallic compound Pr5Ni19, which is not shown in the Pr-Ni binary phase diagram, was synthesized, and the crystal structure was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Two superlattice reflections with the Sm5Co19-type structure (002 and 004) and the Pr5Co19-type structure (003 and 006) were observed in the 2 theta region between 2 degrees and 15 degrees in the XRD pattern using Cu K alpha radiation. Rietveld refinement provided the goodness-of-fit parameter S = 6.7 for the Pr5Co19-type (3R) structure model and S = 1.7 for the Sm5Co19-type (2H) structure model, indicating that the synthesized compound has a Sm5Co19 structure. The refined lattice parameters were a = 0.50010(9) run and c = 3.2420(4) nm. The high-resolution TEM image also clearly revealed that the crystal structure of Pr5Ni19 is of the Sm5Co19 type, which agrees with the results from Rietveld refinement of the XRD data. The P-C isotherm of Pr5Ni19 in the first absorption was clearly different from that in the first desorption. A single plateau in absorption and three plateaus in desorption were observed. The maximum hydrogen storage capacity of the first cycle reached 1.1 H/M, and that of the second cycle was 0.8 H/M. The 0.3 H/M of hydrogen remained in the metal lattice after the first desorption process., AMER CHEMICAL SOC
Inorganic Chemistry, 2011年,
［査読有り］ Position dependence of SS304 and iron phases in welded specimen by neutron diffraction and Bragg-edge transmission methodK. Iwase; T. Sato; K. Mori; T. Kamiyama; T. Ishigaki; Y. Kiyanagi, We investigated the nondestructive examination method by neutron scattering. A welded plate of SS304 (fcc) and iron (bcc) was investigated using neutron diffraction and the Bragg-edge transmission method. We tried to clear the positions of the welded area, SS304 phase, and iron phase and to determine the lattice spacing. The determined value of d (111) for SS304 is 2.07471(8) using neutron diffraction. With Bragg-edge transmission, it is possible to collect the information of a specimen as two-dimensional (2-D) images using a 2-D position sensitive detector at a pulse neutron source. The determined d (111) of SS304 phase indicates between 2.0745(8) and 2.0752(9) depending on the measurement points using Bragg-edge transmission. The same tendency was also seen in iron phase. The determined d (110) of the iron phase is 2.02802(1) using neutron diffraction. The determined d (110) of iron phase indicates between 2.0266(7) and 2.0321(13) using Bragg-edge transmission. The determined d using diffraction exists within that of Bragg-edge transmission. In order to clarify the position dependency of the phase and lattice spacing, the combined diffraction and Bragg-edge transmission is effective., SPRINGER
Metallurgical and Materials Transactions A, 2011年,
［査読有り］ Development of sample holder for in situ neutron measurement of hydrogen absorbing alloyKenji Iwase; Kazuhiro Mori; Yukio Hishinuma; Yoshio Hasegawa; Shuji Iimura; Hiroaki Ishikawa; Takeshi Kamoshida; Toru Ishigaki, We developed a sample holder for in situ measurement of hydrogen absorbing alloy. In order to prevent the hydrogen absorption by vanadium, copper is coated with 2 pm thickness on inner surface of the vanadium holder. The effect of copper coating and the performance of the holder were evaluated by neutron diffraction and PDF profiles. The lattice parameters a and c of La(2)Ni(7) with Ce(2)Ni(7)-type structure were refined as 0.505921(4) and 2.468608(4) nm by Rietveld analysis. The Cu-Cu correlation peak around r = 0.255 nm was not observed in the PDF profile. Thus the holder is useful for in situ measurement of hydrogen absorbing alloy. The diffraction and PDF profiles of La(2)Ni(2)D(x) (0 < x < 10.5) were collected using a deuterium pressure of 3.7 MPa, and the changes of crystal and local structures were clearly observed. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
International Journal of Hydrogen Energy, 2011年,
［査読有り］ Imaging of a spatial distribution of preferred orientation of crystallites by pulsed neutron Bragg edge transmission
H. Sato; O. Takada; K. Iwase; T. Kamiyama; Y. Kiyanagi
Journal of Physics: Conference Series, 2010年, ［査読有り］
Imaging of a spatial distribution of preferred orientation of crystallites by pulsed neutron Bragg edge transmissionH. Sato; O. Takada; K. Iwase; T. Kamiyama; Y. Kiyanagi, A pulsed neutron transmission coupled with a two-dimensional position sensitive neutron detector gives a time-of-flight spectrum at each pixel of the detector, which depends on the total cross-sections of materials. In order to extract quantitative information of the preferred orientation included in the Bragg scattering total cross-section data, a spectral analysis software for the 2D imaging has been developed, and the transmission data of an unbent iron plate were analyzed. The 2D images with respect to the preferred orientation were successfully obtained, and the effectiveness of spectroscopic neutron transmission imaging was indicated., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON NEUTRON SCATTERING 2009, 2010年,
［査読有り］ Microstructure of hydrogenated Mg2Ni studied by SANSK. MOri; M. Sugiyama; K. Iwase; S. Kawabe; Y. Onodera; K. Itoh; T. Otomo and T. Fukunaga, 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, D-S (= 6-m). In conclusion, the hydrogenated and duterated Mg2Ni showed D-S similar to 3 and similar to 2, respectively. The significant difference between D-S's can be understood by considering the scattering length densities, rho, of Mg2Ni, Mg2NiH4, and Mg2NiD4., IOP PUBLISHING LTD
Journal of Physics, 2010年,
［査読有り］ Phase Transformation and Crystal Structure of La2Ni7Hx Studied by in situ X-ray DiffractionKenji Iwase; Kouji Sakaki; Yumiko Nakamura; and Etsuo Akiba†, The phase transformation of La2Ni7 during hydrogenation was investigated by in situ X-ray diffraction. We found two hydride phases, La2Ni7H7.1 (phase I) and La2Ni7H10.8 (phase II), during the first absorption cycle. The metal sublattice of phase I was orthorhombic (space group Pbcn) with lattice parameters a = 0.50128(6) nm, b = 0.8702(1) nm, and c = 3.0377(1) nm. The sublatlice for phase II was monoclinic (space group C2/c) with lattice parameters a = 0.51641(9) nm, b = 0.8960(1) nm, c = 3.1289(1) nm, and beta = 90.17(1)degrees. The lattice parameter c increased with the hydrogen content, while a and b decreased in the formation of phase I from the alloy. Phase transformation from phase I to phase II was accompanied by isotropic expansion. The La2Ni4 and LaNi5 subunit expanded by 48.9% and 6.0% in volume, respectively, during hydrogenation to phase I. They expanded an additional 14% and 5.8%, respectively, in the formation of phase II. The obtained volume expansion suggested different hydrogen distribution in the La2Ni4 and LaNi5 subunit during hydrogenation., AMER CHEMICAL SOC
Inorganic Chemistry, 2010年,
［査読有り］ Ionic conductivity and structural properties of Litium Lanthanum Titanate quenched into liquid nitrogen studied by neutron powder diffractionK. Mori; K. Iwase; M. Yonemura; J. Siewenie; T. Proffen; Y. Onodera; K. Itoh; M. Sugiyama; T. Kamiyama; T. Fukunaga, For Li-7-enriched La2/3-x (Li3xTiO3)-Li-7 samples quenched into liquid nitrogen and cooled in the furnace, impedance measurements and time-of-flight neutron powder diffraction (TOF-NPD) experiments were carried out in order to study the effect of the quenched-into-liquid-nitrogen treatment for the ionic conduction and the structural properties. It was found that the quenched-into-liquid-nitrogen treatment enhances the lithium ionic conductivity in the Li-7-content range between 3x similar to 0.25 and 0.45. Furthermore, the local structure within 6 angstrom not change, according to the atomic pair density function (PDF) analysis., PHYSICAL SOC JAPAN
J. Phys. Soc. Jpn, 2010年,
［査読有り］ Preparation of hydrogen storage alloy membrane and analysis of the surface structure by X-ray reflectivity
K. Mori; M. Hino; T. Fukunaga; K. Iwase; T. Ishigaki
KURRI Prog. Rep. 2008, 2009年
大強度陽子加速器施設（J-PARC）の概要と中性子散乱
岩瀬謙二
技術士, 2009年, ［査読有り］
Srtuctural study of La4MgNi19 hydride by in situ X-ray and neutron powder diffractionJ. Nakamura; K. Iwase; H. Hirakawa; Y. Nakamura; E. Akiba, In situ X-ray and neutron powder diffraction were carried out for the La4MgNi19 alloy sample, which was obtained by annealing under controlled Mg-vapor pressure and temperature. The sample contained five phases: Ce5Co19-type La4MgNi19, Pr5Co19-type La4MgNi19, Gd2Co7-type La3MgNi14, Ce2Ni7-type La3MgNi14, and CaCu5-type LaNi5. Those mass fractions were 51%, 19%, 16%, 4%, and 10%, respectively. The crystal structures for the samples before and after hydrogenation were refined by the Rietveld method. The full hydride of the main phase La4MgN19Dx had a rhombohedral structure (space group: R (3) over barm) with a = 0.53990(3) nm, c = 5.2458(3) nm. Lattice expansions Delta a/a and Delta c/c in hydrogenation were 7.3% and 8.8%, and volume expansion Delta V/V was 25.3%. The hydrogen content D/M obtained from the refinement was 0.91(5), and hydrogen was evenly located in both the MgZn2-type cell and the CaCu5-type cell., AMER CHEMICAL SOC
J. Phys. Chem. C, 2009年,
［査読有り］ Imaging and texture observation of materials by using a pulsed neutron spectroscopic transmission methodY. Kiyanagi; T. Kamiyama; O. Takada; K. Morita; K. Iwase; S. Szuki; M. Furusaka; F. Hiraga; S. Tomioka; K. Mishima; N. Takenaka; T. Ino, Spectroscopic transmission method using a pulsed neutron source combined with a 2-dimensional position sensitive detector is expected to give texture information of materials depending on the position. This method gives not only the transmission imaging of the objects but also the structural imaging obtained by the total cross-section of the materials including the Bragg edges. In order to study the structural change due to welding, we performed transmission experiments and obtained the cross-section map of the welded sample. In the case of welded samples, the cross-section changed depending on the position. It clearly showed the welded region, heat affected region, and as-cast region, and indicated texture change reflecting the cross-section. It suggests that the method will have a possibility to give more information on microstructure of materials, such as density change, grain size and so on. (c) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Nucl. Instr. and Meth, 2009年,
［査読有り］ Distribution of hydrogen metal hydride by in situ powder neutron diffractionY. Nakamura; J. Nakamura; K. Iwase; E. Akiba, Interstitial metal hydrides were studied by in situ powder neutron diffraction for their use in hydrogen storage. The main focus was the distribution of hydrogen atoms in the materials. In full hydrides of LaNi(5-x)Al(x), hydrogen occupation depended strongly on the amount of Al. The symmetry varied from P6(3)mc (x=0) to P6mm (x=0.1) and P6/mmm (x >= 0.25) with change in occupancy of each site. Variation in hydrogen occupation during absorption and desorption was analyzed for LaNi(4.78)Sn(0.22). Redistribution between three tetrahedral sites was observed during desorption. La(5)Ni(19)-based hydrides with a structure consisting of stacking La(2)Ni(4) and LaNi(5) cells were also studied. Rietveld refinement of La(4)MgNi(19)D similar to 24 showed that hydrogen distributed almost evenly in LaMgNi(4) and LaNi5 cells (0.8-1.0 H/M), which was consistent with the uniform lattice expansion of those cells. This result indicated that substitution of Mg for La changed the preferred sites for hydrogen occupation in the La(2)Ni(4) and LaNi(5) cells. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Nucl. Instr. and Meth, 2009年,
［査読有り］ Bragg-edge transmission imaging of strain and microstructure using a pulsed neutron sourceK. Iwase; K.Sakuma; T. Kamiyama; Y. Kiyanagi, The residual strain and the total cross-section in Fe plate was investigated by a Bragg-edge transmission method. The experiments were performed at the position of the time-of-flight diffractometer at KENS, Sirius. The (Delta d/d) reached about 0.1%. The high counting rate and high efficiency pixel type 2d-detector with 8 x 8 pixels was used. The spatial resolution is about 2.1 mm. We clearly observed the image of the change on Bragg-edge shapes and the strain distribution. The total cross-section around the bending points was larger than other areas but there was no change in the Bragg-edge positions, which would correspond to the change of the microstructure. We obtained the image of residual strain at several points. The values of the residual strain at several lattice planes, epsilon(110), epsilon(200) and epsilon(211), are -263 to 1707 mu epsilon, -612 to 1665 mu epsilon and -1205 to 327 mu epsilon, respectively. It is indicated that the residual strain measurement by the Bragg-edge transmission is riot inferior to the high-resolution Bragg diffraction. (C) 2009 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Nucl. Instr. and Meth, 2009年,
［査読有り］ Pulsed neutron spectroscopic imaging for investigation microstructure of materialY. Kiyanagi; T. Kamiyama; T. Nagata; K. Sakuma; H. Iwasa; F. Hiraga; K. Iwase, Imaging using a pulsed neutron time-of-flight method is useful to investigate the microstructure of the texture of materials such as metals. We measured total cross sections over the wavelength region of Bragg edges using a position sensitive detector with 64-pixels of 1.7 mm(2) size. It was found that in the case of an SS plate processed by heat treatment, it had a smaller total cross section than the SS samples with a surface treatment, and fine substructures appeared in the total cross section data corresponding to each Bragg edge in each pixel image. The fine structure may be attributed to inhomogeneous distribution of the rather large crystalline. The results suggest that the pulsed neutron imaging can have the capability to give information of the micro structure of materials., DESTECH PUBLICATIONS, INC
Neutron Radiography, 2008年,
［査読有り］ 局所構造解析と結晶構造解析の併用で明らかになったbcc固溶体型水素吸蔵合金の構造岩瀬謙二,神山崇,森一広,中村優美子,秋葉悦男, The local and crystal structures of the (Ti
0.45Cr
0.35Mo
0.20)-D system have been investigatedby neutron powder diffraction and total neutron scattering. From the result of neutronpowder diffraction, the crystal structure of the system was found to change from CaF
2-type structure to bcc structure in hydrogen desorption process, and the D atoms occupythe tetrahedral (T) sites in both CaF
2-type and bcc phases. The nearest neighbor coordinationnumber around a D atom has been obtained by the RDF analysis of total neutron scatteringdata. The D atoms occupy the T sites surrounded mainly by the Ti atoms in both CaF
2-type and bcc phases., The Japanese Society for Neutron Science
波紋, 2007年,
［査読有り］ 北大45MeV小型電子加速器を用いた最近の研究鬼柳善明,岩瀬謙二,加美山隆,古坂道弘,住吉孝,西山修輔,富岡智,秋本正, 日本加速器学会
加速器, 2007年,
［査読有り］ Hydration kinetick of tricalcium silicate
K. Mori; Y. Shiraishi; K. Iwase; M. Yonemura; F. Shikanai; T. Wuernisha; D. Sulistyanintyas; K. Itoh; M. Sugiyama; T. Kamiyama; K. Oishi; M. Kawai; T. Fukunaga
KENS Report XV 2003 ? 2006, 2006年
High temperature phase of Fe?doped lanthanum gallate
K. Mori; K. Shibata; T. Fukunaga; K. Itoh; M. Sugiyama; K. Iwase; S. Harjo; A. Hoshikawa; T. Ishigaki; T. Kamiyama
KENS Report XV 2003 ? 2006, 2006年
Development of Rietveld?PDF collaboration analysis system on Vega
K. Mori; T. Fukunaga; K. Iwase; T. Wuernisha; M. Yonemura; D. Sulistyanintyas; F. Shikanai; K. Itoh; M. Sugiyama; T. Ishigaki; T. Kamiyama
KENS Report XV 2003 ? 2006, 2006年
Average and Local Structures in Hydrogen Absorbing Ti-Cr-Mo AlloyK. Iwase; T. Kamiyama; Y. Nakamura; K. Mori; M. Yonemura; S. Harjo; T. Ishigaki and E. Akiba, The average and local structures in the (Ti0.45Cr0.35Mo0.20)-D system have been investigated by neutron powder diffraction and total neutron scattering. From the result of neutron powder diffraction, the crystal structure of the system Was found to change from CaF2-type structure to bee structure in the hydrogen desorption process, and the D atoms occupy the tetrahedral (T) sites in both CaF2-type and bee phases. The D-Ti, D-Cr, D-Mo and D-D correlation lengths and the nearest neighbor coordination number around a D atom have been obtained by the RDF analysis of total neutron scattering data. The 1) atoms occupy the T sites surrounded mainly by the Ti atoms in both CaF2-type and bee phases., JAPAN INST METALS
Mater. Trans., 2006年,
［査読有り］ Structural and hydration properties of amorphous tricalcium silicateK. Mori; T. Fukunaga; Y. Shiraishi; K. Iwase; Q. Xu; K. Oishi; K. Yatsuyanagi; M. Yonemura; K. Itoh; M. Sugiyama; T. Ishigaki; T. Kamiyama and M. Kawai, Mechanical milling was carried out to synthesize amorphous tricalcium silicate (Ca3SiO5) sample, where Ca3SiO5 is the most principal component of Portland cement. The partial phase transformation from the crystalline to the amorphous state was observed by X-ray and neutron diffractions. Moreover, it was found that the structural distortion on the Ca-O correlation exists in the milled Ca3SiO5. The hydration of the milled Ca3SiO5 with D2O proceeds as follows: the formation of hydration products such as Ca(OD)(2) rapidly occurs in the early hydration stage, and then proceeds slowly after about 15 h. The induction time for the hydration of the milled Ca3SiO5 is approximately one half shorter than that for the hydration of the unmilled one. This result means that the mechanical milling brings about the chemical activity of Ca3SiO5 for hydration, and may be particularly useful for increasing the reactivity in the early hydration stage. (c) 2006 Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Cement&Concrete Res., 2006年,
［査読有り］ Charge states of Ca atoms in s-dicalcium silicateK. Mori; R. Kiyanagi; M. Yonemura; K. Iwase; T. Sato; K. Itoh; M. Sugiyama; T. Kamiyama and T. Fukunaga, In order to study the crystal structure of beta-Ca2SiO4, time-of-flight neutron powder diffraction experiments were carried out at temperatures between room temperature (RT) and 600 degrees C. Rietveld refinement at RT has shown that beta-Ca2SiO4 is monoclinic based on P2(1)/n symmetry and two different types of Ca sites, Ca(1) and Ca(2). All interatomic distances within 3 angstrom were calculated, with the valences of Ca(1) with seven Ca-O bonds and Ca(2) with eight were estimated to be 1.87+ and 2+ by the Zachariasen-Brown-Altermatt formula (bond valence sum). Applying charge neutrality the two charge states of Ca in beta-Ca2SiO4 are [Ca(1)SiO4](2-) and Ca(2)(2+), respectively. Furthermore, the [Ca(1)SiO4](2-) unit has the shortest Ca-O distance, and its length kept constant at 2.23 angstrom at all temperatures. In the short-range structure analysis at RT, the shortest Ca-O bond was also observed in a radial distribution function. These results imply that the [Ca(1)SiO4](2-) unit has covalency on the shortest Ca-O in addition to Si-O. (c) 2006 Elsevier Inc. All rights reserved., ACADEMIC PRESS INC ELSEVIER SCIENCE
J. Solid State Chem., 2006年,
［査読有り］ Hydration Kinetics of Tricalcium Silicate Studied by Neutron Scattering5. K. Mori; Y. Shiraishi; T. Sato; K. Iwase; M. Sugiyama; S. Takata; T. Otomo; K. Itoh; M. Yonemura; F. Shikanai; T. Wuernisha; D. Sulistyanintyas; K. Oishi; M. Kawai; T. Kamiyama and T. Fukunaga, The hydration kinetics of tricalcium silicate (Ca3SiO5) has been studied by time-of-flight neutron powder diffraction (TOF-NPD) and time-of-flight small-angle neutron scattering (TOF-SANS). During the hydration process, the hydrated Ca3SiO5 was quantified using the additional standard method with Si, and then we could obtain the time dependence of the hydration degree of Ca3SiO5. It was validated that the hydration of Ca3SiO5 proceeds in three different stages: induction period, nucleation and growth period and diffusion-limited period. In the SANS experiments, the drastic variation in the SANS curve was observed over induction time (t(i)similar to 6 h). From these results, we point out that the hydration rate is strongly associated with the surface roughness of Ca3SiO5 arising from the creation of hydration products. Furthermore, the four-parameter equation based on the Avrami model was applied to describe the hydration kinetics of Ca3SiO5. The n-value that characterizes the hydration process was estimated as similar to 2.6., ELSEVIER SCIENCE BV
Trans. Mater. Res. Soc. Jpn, 2006年,
［査読有り］ Structural and Hydration Properties of Low Heat Portland Cement10. K. Mori; T. Sato; K. Iwase; Y. Inamura; O. Yamamuro; K. Oishi; K. Kimura; K. Itoh; M. Sugiyama; M. Kawai and T. Fukunaga, In order to study the structural and hydration properties of Low Heat Portland Cement (LHPC), X-ray powder diffraction (XPD) and quasi-elastic neutron scattering (QENS) experiments were performed. In the Rietveld refinement of LHPC, it was validated that the principal component of LHPC is Ca2SiO4 of which structure has the monoclinic beta-phase. The QENS experiments showed the hydration behavior of LHPC; three different stages (induction period, nucleation and growth period and diffusion-limited period) are clearly observed in the bound water index, BWI, as a function of hydration time. Moreover, the initial hydration process of LHPC could be described by a four-parameter equation based on the Avrami model., ELSEVIER SCIENCE BV
Trans. Mater. Res. Soc. Jpn, 2006年,
［査読有り］ Neutron Powder Diffraction Study of K3H(SeO4)2 in the High-Temperature Phase11. F. Shikanai; R. Kiyanagi; M. Yonemura; D. Sulistyanintyas; K. Iwase; T. Wuernisha; K. Mori; T. Ishigaki; S. Ikeda and T. Kamiyama, Neutron powder diffraction measurements were carried out on K3H(SeO4)(2) at 413 K in the protonic conducting phase (phase I) and at 298 K in the room-temperature phase (phase II) using a time-of-flight (TOF) neutron diffractometer VEGA. The crystal structures and nuclear density distribution maps were obtained by the Rietveld method and maximum entropy method (MEM). In the phase I, a proton in the hydrogen bond is disordered and SeO4 tetrahedron is rotationally displaced. The structure in the phase II locally remains even in the phase I. The amount of the proton in the hydrogen bond region varies from 87% for the phase II to 21% for the phase I. In the phase I, the proton densities were also obtained in the inter SeO4 layers space with the amount of 13%. (c) 2006 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Physica B, 2006年,
［査読有り］ Observation of Microstructure of Hydrated Ca3SiO512. K. Mori; T. Sato; T. Fukunaga; K. Oishi; K. Kimura; K. Iwase; M. Sugiyama; K. Itoh; F. Shikanai; T. Wuernisha; M. Yonemura; D. Sulistyanintyas; I. Tsukushi; T. Otomo; T. Kamiyama and M. Kawai, Quasi-elastic neutron scattering experiments were carried out to evaluate the hydration rate of tricalcium silicate (Ca3SiO5)Furthermore, in the early hydration period, a variation in surface roughness of Ca3SiO5 was observed in nano-scale by the small-angle neutron scattering. From these results, it was found that the hydration rate of Ca3SiO5 is suppressed when the surface of Ca3SiO5 becomes rough through the creation of hydration products C-S-H gel and Ca(OH)(2), and this roughness is associated with changes in the Ca3SiO5 hydration rate. (c) 2006 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Physica B, 2006年,
［査読有り］ Structure phase transition of FeSr2YCu2O6+13. T. Mochiku; Y. Hata; K. Iwase; M. Yonemura; S. Harjo; A. Hoshikawa; K. Oikawa; T. Ishigaki; T. Kamiyama; H. Fujii; F. Izumi; K. Kadowaki and K. Hirata, FeSr(2)yCu(2)O(6+delta) exhibits superconductivity around 50K, when it is property annealed in N-2 atmosphere and subsequently in O-2 atmosphere, although as-synthesized FeSr2YCu2O6+delta does not exhibit superconductivity. To understand the effect of annealing on superconductivity, we have performed in-situ high-temperature neutron powder diffraction measurements in N-2 atmosphere. We have found that the N-2 annealing at 650 degrees C promoted the atomic ordering of Cu and Fe and that the phase transition occurred from tetragonal structure to orthorhombic superstructure at 750 degrees C. The atomic ordering of Cu and Fe did not change at all during the following annealing process. Consequently, this compound exhibits superconductivity by supplying the carrier onto the CuO2 sheet. (c) 2006 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Physica B, 2006年,
［査読有り］ Structural Studies of Hydrated Tricalcium Silicate by Neutron Powder DiffractionK. Mori; K. Yatsuyanagi; K. Oishi; T. Fukunaga; T. Kamiyama; T. Ishigaki; A. Hoshikawa; S. Harjo; K. Iwase; K. Itoh and M. Kawai, Structure refinements have been carried out on the pure tricalcium silicate (C3S) and the hydrated C3S with the D2O-C3S mass ratio, which is 0.5, using neutron powder diffraction (NPD). The multi-phase Rietveld analysis of the hydrated C3S revealed the coexistence with the Ca(OD)2 (trigonal phase) and the unhydrated C3S (triclinic one). The Ca(OD)2 phase was hardly observed on the NPD patterns in the first ∼6 h of hydration, while the several Bragg reflections of Ca(OD)2 appeared drastically from ∼6 to ∼24 h, and then the hydration reaction rate was gradually suppressed. We could apply the Avrami-model to the initial hydration reaction process of C3S. © 2005 Taylor &
Francis Ltd.
J. Neu. Res., 2005年,
［査読有り］ Structural effect for Fe-doping in LaGa1-xFexO3-
K. Mori; T. Fukunaga; K. Shibata; K. Itoh; K. Iwase; M. Yonemura; M. Sugiyama
Trans. Mater. Res. Soc. Jpn, 2005年, ［査読有り］
Hydrogen absorption-desorption properties and crystal structure analysis of Ti-Cr-MoK. Iwase; Y. Nakamura; K. Mori; S. Harjo; T. Ishigaki; T. Kamiyama and E. Akiba, We investigated that heat treatment condition, hydrogen absorption-desorption properties and crystal structure of Ti-(55-x)Cr-xMo alloys by the use of X-ray diffraction (XRD) and PCT measurement. We found that the quenching treatment was effective to synthesize bcc single phase alloys in comparison with annealing treatment. The lattice parameter, a, of bcc phase in the quenched alloys showed linear relationship with increasing the Mo content. The as-cast alloys had a sloping plateau, while the quenched alloys had a flat plateau. The alloys showed the equilibrium pressure increased with increasing the Mo content. The hydrogen reversible capacity of the alloys reached 1.33-1.39 H/M (2.34-2.68 mass%) under hydrogen pressure 8.0 MPa at 313 K. (c) 2005 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
J. Alloys and Compd, 2005年,
［査読有り］ Structural Properties of Fe-doped Lanthanum GallateK. Mori; T. Fukunaga; K. Shibata; K. Iwase; S. Harjo; A. Hoshikawa; K. Itoh; T. Kamiyama and T. Ishigaki, Structural characteristics of Fe-doped LaGaO3-delta were studied by differential scanning calorimeter, neutron and high-temperature X-ray powder diffraction measurements. It was found that a phase transition temperature increases in proportion to an amount of Fe. The crystal structure could be described as a low-temperature orthorhombic phase (Pnma) and a high-temperature rhombohedral one (R3c), respectively. Lattice parameters and bond lengths between M (=Ga/Fe) and O are monotonically expand with increasing Fe-content on both orthorhombic and rhombohedral phases. This means that a substitution of Ga3+ with Fe3+ leads to an electronic configuration of t(2g)(3)e(g)(2) (high-spin state, HS). (C) 2004 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Physica B, 2004年,
［査読有り］ Crystal Structure Analysis of Biominerals
K. Iwase; T. Kamiyama; S. Torii; K. Mori; H. Asano
J. Phys. Soc. Jpn., 2001年, ［査読有り］
