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Journal Articles

A Raman spectroscopy study of bicarbonate effects on UO $_{2+x}$

McGrady, J.; Kumagai, Yuta; Watanabe, Masayuki; Kirishima, Akira*; Akiyama, Daisuke*; Kimuro, Shingo; Ishidera, Takamitsu

Journal of Nuclear Science and Technology, 60(12), p.1586 - 1594, 2023/12

https://doi.org/10.1080/00223131.2023.2236104

Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)

Journal Articles

Study on the relation between the crystal structure and thermal stability of FeUO $_{4}$ and CrUO $_{4}$

Akiyama, Daisuke*; Kusaka, Ryoji; Kumagai, Yuta; Nakada, Masami; Watanabe, Masayuki; Okamoto, Yoshihiro; Nagai, Takayuki; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

https://doi.org/10.1016/j.jnucmat.2022.153847

Times Cited Count：3 Percentile：68.71(Materials Science, Multidisciplinary)

FeUO $_{4}$ , CrUO $_{4}$ , and Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ are monouranates containing pentavalent U. Even though these compounds have similar crystal structures, their formation conditions and thermal stability are significantly different. To determine the factors causing the difference in thermal stability between FeUO $_{4}$ and CrUO $_{4}$ , their crystal structures were evaluated in detail. A Raman band was observed at 700 cm $^{-1}$ in all the samples. This Raman band was derived from the stretching vibration of the O-U-O axis band, indicating that Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ was composed of a uranyl-like structure in its lattice regardless of its "x"' value. Mssbauer measurements indicated that the Fe in FeUO $_{4}$ and Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ were trivalent. Furthermore, Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ lost its symmetry around Fe $^{mathrm{III}}$ with increasing electron densities around Fe $^{mathrm{III}}$ , as the abundance of Cr increased. These results suggested no significant structural differences between FeUO $_{4}$ and CrUO $_{4}$ . Thermogravimetric measurements for UO $_{2}$ , FeUO $_{4}$ , and CrUO $_{4}$ showed that the temperature at which FeUO $_{4}$ decomposed under an oxidizing condition (approximately 800 $^{circ}$ C) was significantly lower than the temperature at which the decomposition of CrUO $_{4}$ started (approximately 1250 $^{circ}$ C). Based on these results, we concluded that the decomposition of FeUO $_{4}$ was triggered by an "in-crystal" redox reaction, i.e., Fe $^{mathrm{III}}$ U $^{mathrm{V}}$ Fe $^{mathrm{II}}$ U $^{mathrm{VI}}$ , which would not occur in the CrUO $_{4}$ lattice because Cr $^{mathrm{III}}$ could never be reduced under the investigated condition. Finally, the existence of Cr $^{mathrm{III}}$ in FexCr $_{1-x}$ UO $_{4}$ effectively suppressed the decomposition of the Fe $_{x}$ Cr $_{1-x}$ UO $_{4}$ crystal, even at a very low Cr content.

Journal Articles

Geopolymer and ordinary Portland cement interface analyzed by micro-Raman and SEM

Cantarel, V.; Yamagishi, Isao

Journal of Nuclear Science and Technology, 59(7), p.888 - 897, 2022/07

https://doi.org/10.1080/00223131.2021.2016510

Times Cited Count：2 Percentile：53.91(Nuclear Science & Technology)

Journal Articles

Multipole polaron in the devil's staircase of CeSb

Arai, Yosuke*; Kuroda, Kenta*; Nomoto, Takuya*; Tin, Z. H.*; Sakuragi, Shunsuke*; Bareille, C.*; Akebi, Shuntaro*; Kurokawa, Kifu*; Kinoshita, Yuto*; Zhang, W.-L.*; et al.

Nature Materials, 21(4), p.410 - 415, 2022/04

https://doi.org/10.1038/s41563-021-01188-9

Times Cited Count：7 Percentile：77.62(Chemistry, Physical)

Journal Articles

Application of an augmentation method to MCR-ALS analysis for XAFS and Raman data matrices in the structural change of isopolymolybdates

Saeki, Morihisa*; Yomogida, Takumi; Matsumura, Daiju; Saito, Takumi*; Nakanishi, Ryuzo*; Tsuji, Takuya; Oba, Hironori*

Analytical Sciences, 36(11), p.1371 - 1378, 2020/11

https://doi.org/10.2116/analsci.20P147

Times Cited Count：2 Percentile：10(Chemistry, Analytical)

We measured X-ray absorption fine structure (XAFS) and Raman spectra of isopolymolybdates(VI) in HNO $_{3}$ solution (0.15- 4.0 M), which change their geometries depending on acid concentration, and performed simultaneous resolution of the XAFS and Raman data using a multivariate curve resolution by alternating least-squares (MCR-ALS) analysis. In iterative ALS optimization, initial data matrices were prepared by two different methods. The MCR-ALS result of single XAFS data matrix shows large dependence on the preparation method of the initial data matrices. The MCR-ALS result of an augmented matrix of Raman and XAFS data has little dependence on the initial data matrices. It indicates that the augmentation method effectively improves the rotation ambiguities in the MCR-ALS analysis of the XAFS data. Based on the model fitting of the pure EXAFS oscillations, we revealed the change of [Mo $_{36}$ O $_{112}$ (H $_{2}$ O) $_{16}$ ] $^{2+}$ [Mo $_{2}$ O $_{5}$ (H $_{2}$ O) $_{6}$ ] $^{2+}$ [HMoO $_{3}$ (H $_{2}$ O) $_{3}$ ] $^{+}$ in the highly concentrated HNO $_{3}$ solution.

Journal Articles

Behavior of cesium molybdate, Cs $_{2}$ MoO $_{4}$ , in severe accident conditions, 1; Partitioning of Cs and Mo among gaseous species

Do, Thi Mai Dung*; Sujatanond, S.*; Ogawa, Toru

Journal of Nuclear Science and Technology, 55(3), p.348 - 355, 2018/03

https://doi.org/10.1080/00223131.2017.1397560

Times Cited Count：6 Percentile：52.79(Nuclear Science & Technology)

In order to better understand the behavior of cesium in the severe accident of the LWR, the high-temperature chemistry of Cs $_{2}$ MoO $_{4}$ in H $_{2}$ O+H $_{2}$ gas was studied. The pseudo-binary system, Cs $_{2}$ MoO $_{4}$ -MoO $_{3}$ , was thermochemically modeled with Redlich-Kister formulation to form a basis to analyze the high-temperature behavior of Cs $_{2}$ MoO $_{4}$ . The model prediction was compared with the thermogravimetric measurements of Cs $_{2}$ MoO $_{4}$ in dry and humid argon, which revealed that the mass-loss rate was enhanced in the humid atmosphere. Thermochemical model was further applied to predict the partitioning of cesium and molybdenum among gaseous species in the BWR core degradation condition typical of Short-Term Station Blackout.

Journal Articles

Investigation of ruthenium compounds in the vitrification process condition

Nagai, Takayuki; Sato, Nobuaki*; Sasage, Kenichi

Busshitsu, Debaisu Ryoiki Kyodo Kenkyu Kyoten Kenkyu Seika Hokokusho (Heisei-27-Nendo) (CD-ROM), 2 Pages, 2016/03

no abstracts in English

Journal Articles

Infrared absorption and Raman scattering spectra of water under pressure via first principles molecular dynamics

Ikeda, Takashi

Journal of Chemical Physics, 141(4), p.044501_1 - 044501_8, 2014/07

https://doi.org/10.1063/1.4890369

Times Cited Count：15 Percentile：51.43(Chemistry, Physical)

From both the polarized and depolarized Raman scattering spectra of supercritical water a peak located at around 1600 cm $^{-1}$ , attributed normally to bending mode of water molecules, was experimentally observed to vanish, whereas the corresponding peak remains clearly visible in the measured infrared (IR) absorption spectrum. In this computational study a theoretical formulation for analyzing the IR and Raman spectra is developed via first principles molecular dynamics combined with the modern polarization theory. We demonstrate that the experimentally observed peculiar behavior of the IR and Raman spectra for water are well reproduced in our computational scheme. We discuss the origins of a feature observed at 1600 cm $^{-1}$ in Raman spectra of ambient water.

Journal Articles

Polymerization of C $_{60}$ thin films by ion irradiation

Narumi, Kazumasa; Sakai, Seiji; Naramoto, Hiroshi*; Takanashi, Koki

JAEA-Review 2005-001, TIARA Annual Report 2004, p.238 - 240, 2006/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2005-001-p0127-p0267.pdf

no abstracts in English

Journal Articles

Characterization of C $_{60}$ films polymerized by ion irradiation

Narumi, Kazumasa; Sakai, Seiji; Naramoto, Hiroshi*; Takanashi, Koki

Fullerenes, Nanotubes, and Carbon Nanostructures, 14(2-3), p.429 - 434, 2006/00

no abstracts in English

Journal Articles

CARS study of deuterium clusters stabilized in solid helium

Gordon, E. B.*; Kumada, Takayuki; Ishiguro, Masazumi; Aratono, Yasuyuki

Journal of Experimental and Theoretical Physics, 99(4), p.776 - 783, 2004/10

The solid Deuterium clusters for the first time isolated in a matrix of solid Helium have been investigated at T = 1.3K and P = 3 MPa by CARS (Coherent anti-Stokes Raman spectroscopy) technique. The Q1(J=0) and Q1(J=1) lines intensity, shape and positions have been studied as the functions of ortho- para content in the solid, as well as of clusters size. The strong effect of Raman scattering cross section sensitivity to the molecular environment nuclear spin state has been found in CARS; the ratio of probabilities for the scattering by para (J=1) and ortho (J=0) deuterium being equal to 1 in a gas is as high as 10,000 in nearly pure o-D2, whereas it is about 50 in spontaneous Raman scattering. This effect has been shown to give rise starting from cluster size corresponding to the phonon band onset.

Journal Articles

Glass formation at the limit of insufficient network formers

Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*; Loong, C.-K.*; Grimsditch, M.*; Weber, J. K. R.*; Tangeman, J. A.*; Key, T. S.*

Science, 303(5664), p.1649 - 1652, 2004/03

https://doi.org/10.1126/science.1095047

Times Cited Count：158 Percentile：96.05(Multidisciplinary Sciences)

Inorganic glasses normally exhibit a network of interconncted covalent-bonded structural elements that has no long-range order. In silicate glasses the network formers are based on SiO-tetrahedra interconnected via oxygen atoms at the corners. Conventional wisdom then implies that alkaline and alkaline-earth orthosilicate materials cannot be vitrified because they do not contain sufficient network forming SiO to establish the needed interconnectivity. We have studied a bulk magnesium orthosilicate glass obtained by containerless melting-and-cooling. We find that the role of network former is largely taken on by corner- and edge-sharing of highly distorted ionic Mg-O species that adopt 4-, 5- and 6-coordination with oxygen. The results suggest that similar novel glassy phases may be found in the containerless environment of interstellar space.

Journal Articles

Structure evolution and corresponding electrical properties in weakly bound Co-C60 mixture

Sakai, Seiji; Naramoto, Hiroshi; Xu, Y.; Priyanto, T. H.; Lavrentiev, V.; Narumi, Kazumasa

Materials Research Society Symposium Proceedings, Vol.788, p.L11.49.1 - L11.49.6, 2004/00

https://doi.org/10.1557/PROC-788-L11.49

Mixture films between cobalt and C $_{60}$ (CoxC $_{60}$ , x = 0.5-700) were prepared by co-evaporation technique under UHV conditions. The composition-dependent features of dilatation and downshift of Raman peak suggest that the mixtures are composed of cobalt particles and a C $_{60}$ -based phase in which certain number of cobalt atoms are coordinated with C $_{60}$ molecules. It is deduced that the equilibrated number of cobalt atoms in the C $_{60}$ -based phase is 4 atoms per C $_{60}$ molecule and in which an electron transfer occurs from a cobalt atom to a C $_{60}$ molecule. The evaluation of their temperature dependences reveals that: (1) The mixtures with x 4 are thermally activated-type, and their conductive nature can be attributed to the C $_{60}$ -based phase. Further (2) the mixtures between 4 x 60 are also thermally activated, however, the electron hopping process between the isolated cobalt particles is supposed to be operative (variable-range-hopping). And (3) in the mixtures with x 60 which corresponds to a percolation threshold for cobalt particles, the system changes into metallic conduction.

Journal Articles

Photoluminescence and Raman studies of curium and americium complexes of 6-methyl 2-(2-pyridyl)- benzimidazole; Evidence for an efficient intramolecular energy transfer

Assefa, Z.*; Yaita, Tsuyoshi; Haire, R. G.*; Tachimori, Shoichi

Inorganic Chemistry, 42(23), p.7375 - 7377, 2003/11

https://doi.org/10.1021/ic034759y

Times Cited Count：11 Percentile：36.73(Chemistry, Inorganic & Nuclear)

The 6-methyl- 2-(2-pyridyl)-benzimidazole (biz) ligand coordinates with the actinide species in solution, and the complexes display efficient intra-molecular energy-transfer processes. The energy transfer in the Cm(III):biz system proceeds in a non-radiative mode, whereas a radiative mode is the principal mechanism in the Am(III)-biz system.

Journal Articles

Strong anti-stokes luminescence from H $^{+}$ -irradiated diamond

Xu, Y.; Naramoto, Hiroshi; Narumi, Kazumasa; Miyashita, Kiyoshi*; Kamiya, Tomihiro; Sakai, Takuro

Applied Physics Letters, 83(10), p.1968 - 1970, 2003/09

https://doi.org/10.1063/1.1608465

Times Cited Count：6 Percentile：28.18(Physics, Applied)

no abstracts in English

Journal Articles

The Resonance Raman effect of uranyl formate in dimethyl sulfoxide

Soga, Takeshi

Spectrochimica Acta, Part A, 59(11), p.2497 - 2510, 2003/09

no abstracts in English

JAEA Reports

Study on the stress corrosion cracking of zirconium in nuclear fuel reprocessing environment

Kato, Chiaki

JAERI-Research 2003-013, 143 Pages, 2003/08

JAERI-Research-2003-013.pdf:22.12MB

This study is investigation about stress corrosion cracking (SCC) of zirconium in nuclear fuel reprocessing. Chapter 1 is described background. Chapter 2 is explained experimental apparates. Chapter 3 is described the increased oxidization potential on the heat-transfer surface and suggested the initiation of SCC on a boiling heat-transfer surface. Chapter 4 is described that the SCC susceptibility increased with increasing nitric acid concentration and solution temperature on notched specimen by SSRT. In addition, the SCC susceptibility effected by the crystal anisotropy by the hot rolling direction and increased on a parallel face to the rolling direction. Chapter 5 is described that the SCC susceptibility increased in HAZ/base metal boundary in order to the preferential orientation of cleavage plane (0002). Chapter 6 is described that the increased oxidization potential on the heat-transfer surface is attributed to the reduction of nitrous acid concentration by the thermal decomposition on the surface and the removal of the decomposition product from solution by boiling bubbles.

Journal Articles