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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

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. M$"o$ssbauer 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$$^{mathrm{V}}$$ $$rightarrow$$ 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

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

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

 Times Cited Count:0 Percentile:0(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)$$_{16}$$]$$^{2+}$$ $$rightarrow $$ [Mo$$_{2}$$O$$_{5}$$(H$$_{2}$$O)$$_{6}$$]$$^{2+}$$ $$rightarrow $$ [HMoO$$_{3}$$(H$$_{2}$$O)$$_{3}$$]$$^{+}$$ in the highly concentrated HNO$$_{3}$$ solution.

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

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

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

 Times Cited Count:4 Percentile:20.93(Physics, Applied)

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

Structure and optical properties of germanium implanted with carbon ions

Wei, P.; Xu, Y.; Nagata, Shinji*; Narumi, Kazumasa; Naramoto, Hiroshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.233 - 236, 2003/05

 Times Cited Count:5 Percentile:39.95(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Mesoscopic patterning induced by co-deposition of C$$_{60}$$ and Ni on the MgO(100) single crystal

Vacik, J.; Naramoto, Hiroshi; Narumi, Kazumasa; Yamamoto, Shunya; Miyashita, Kiyoshi*

Materials Research Society Symposium Proceedings, Vol.648, p.P3.50.1 - P3.50.6, 2001/00

None

Journal Articles

The Effect of sputtering ions on the structure and properties of diamond-like carbon films

Zhang, Z.; Narumi, Kazumasa; Naramoto, Hiroshi; Wu, Z.*; Yamamoto, Shunya; Miyashita, Atsumi

Journal of Physics; Condensed Matter, 11(25), p.L273 - L277, 1999/06

 Times Cited Count:3 Percentile:13.27(Physics, Condensed Matter)

no abstracts in English

JAEA Reports

Air oxidation behavior of fuel for the High Temperature Engineering Test Reactor(HTTR)

; Hayashi, Kimio; Fukuda, Kosaku

JAERI-M 92-114, 20 Pages, 1992/08

JAERI-M-92-114.pdf:1.06MB

no abstracts in English

Journal Articles

Dynamic properties of lithium ions in lithium ceramics

Igawa, Naoki; Ono, Hideo; Nagasaki, Takanori; Ishii, Yoshinobu; Noda, Kenji; Watanabe, H.; Matsuo, Toru*; Igarashi, Kazuo*

Ceramic Transactions, Vol.27, p.135 - 156, 1992/00

no abstracts in English

Journal Articles

Fabrication and physical properties of AlF$$_{3}$$-BeF$$_{2}$$ based fluoride glasses for IR transmission

Ono, Hideo; Igawa, Naoki; Ishii, Yoshinobu; Umesaki, Norimasa*; *

Journal of Nuclear Materials, 191-194, p.525 - 529, 1992/00

no abstracts in English

Journal Articles

Development of in-situ gas analyzer for hydrogen isotopes in fusion fuel gas processing

Okuno, Kenji; *; Ohira, Shigeru; Naruse, Yuji

Journal of Nuclear Science and Technology, 28(6), p.509 - 516, 1991/06

no abstracts in English

Journal Articles

Grain size dependence of thermal-shock resistance of yttria-doped tetragonal zirconia polycrystals

*; *; *; *; Ono, Hideo; Igawa, Naoki; Nagasaki, Takanori

Journal of the American Ceramic Society, 73(8), p.2523 - 2525, 1990/00

 Times Cited Count:12 Percentile:54.49(Materials Science, Ceramics)

no abstracts in English

Journal Articles

Kinetic mechanism for air oxidation of PAN T-300 carbon fiber

Nomura, Shinzo; Saito, Tamotsu; Imai, Hisashi

Tanso, 0(140), p.275 - 281, 1989/00

no abstracts in English

Journal Articles

Chemical sputtering of sintered diamond compacts and diamond film

J.Vac.Sci.Technol.,A, 5(4), p.2222 - 2226, 1987/04

no abstracts in English

Oral presentation

Composition optimization of iron phosphate glasses for radioactive sludge

Takebe, Hiromichi*; Kitamura, Naoto*; Amamoto, Ippei; Kobayashi, Hidekazu; Mitamura, Naoki*; Tsuzuki, Tatsuya*

no journal, , 

The great amount of water used for cooling the stricken power reactors at Fukushima Dai-ichi following the earthquake and tsunami on March 11, 2011 has resulted in the accumulation of the remaining water. The water is subsequently contaminated by fission products and some other radioactive substances. The initial treatment to remove the radioactive substances from the cooling water again produced a secondary radioactive waste, the sludge. Iron phosphate glass powder/frit and main component of raw materials for simulated sludge, e.g., barium sulfate and potassium nickel ferrocyanide with various concentrations, were mixed for melting batch. The temperature required for the formation of homogeneous melt was determined by the direct observation of sample decomposition and melting processes on the thermocouple filament through a microscope. The mixtures for bulk glasses were melted in air using platinum crucibles. The quenched glass samples consisted mainly of oxide constituents due to the decomposition of the sludge components during heating and melting processes. Characteristic temperatures of glass transition, Tg, and onset of crystallization, Tx, was determined by differential thermal analysis. Thermal stability against crystallization for the glass samples was evaluated by the temperature difference between Tx and Tg. Water durability was determined by the weight change per a specific surface area after immersion test in hot water at 120$$^{circ}$$C for 72 hours based on MCC-2 static leaching method. Phosphate network species and chemical bonding were characterized by Raman spectroscopy. Glass composition melted with the stimulated sludge components is optimized in terms of both thermal stability and water durability with the characterization of O/P molar ratio.

Oral presentation

In situ Raman spectroscopy on nuclear materials in hot cell

Miro, S.*; Peuget, S.*; Tupin, M.*; Fayette, L.*; Nakayoshi, Akira; Perrin, S.*; Jegou, C.*

no journal, , 

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