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Nagai, Takayuki; Aoyama, Yusuke; Okamoto, Yoshihiro; Hasegawa, Takehiko*; Sato, Seiichi*; Kikuchi, Tetsuya*; Hatakeyama, Kiyoshi*
JAEA-Research 2025-012, 43 Pages, 2026/01
JAEA-Research-2025-012.pdf:6.99MB
In the vitrification process study of high-level radioactive waste liquids, precipitates present in the simulated waste glasses are detected by X-ray diffraction (XRD), but due to the state of the precipitates (fine size, extremely small amount), precipitate peaks cannot be observed in the XRD pattern. We have evaluated the glass structure of simulated waste glasses prepared under different melting and coagulated conditions using Raman spectroscopy and other methods, in this study. The simulated waste glass, which does not show any precipitate peaks in the XRD pattern, was subjected to Raman spectroscopy, and it was confirmed that precipitate particles in the glass phase could be detected. And it was confirmed that in glass preparation, stirring the molten glass and increasing the cooling rate from the molten state are likely to suppress the formation of precipitate particles in the glass phase. The evaluation of the Si-O bridging structure of the glass revealed no difference in the Si-O bridging structure between areas with and without precipitates. The precipitates detected by Raman spectroscopy are not ceria (CeO
) or calcium molybdate (CaMoO
), but they are presumed to be compounds such as spinel. In experiments using synchrotron radiation, X-ray transmission images of the internal state of glasses were observed, and it was confirmed that stirring molten glass is effective in reducing bubbles present in the glass phase. The XAFS measurements of Mo K-edge, Ce L
-edge, and Si K-edge confirmed that stirring the molten glass does not affect the chemical state of Mo, Ce, and Si contained in the glass.
Nagai, Takayuki; Aoyama, Yusuke; Okamoto, Yoshihiro; Shibata, Daisuke*; Asakura, Kiyotaka*; Hasegawa, Takehiko*; Sato, Seiichi*; Fukaya, Akane*; Kikuchi, Tetsuya*; Hatakeyama, Kiyoshi*
JAEA-Research 2025-009, 122 Pages, 2025/11
JAEA-Research-2025-009.pdf:20.77MB
XAFS measurements in the soft X-ray region are suitable for evaluating the chemical state of the surface layer of a measurement sample because the X-ray transmittance is low. This study measured the K-edges of the glass-forming elements boron (B), oxygen (O), sodium (Na), and silicon (Si), as well as the L-edge of the waste component cerium (Ce), to verify the differences between the coagulated layer and the inside of simulated waste glasses made from raw glass compositions with increased alumina concentration. As a result, from the B K-edge XANES spectra, the proportion of B-O tetracoordinate sp
structures (BO) on the surface layer of the coagulated glass samples was higher than that on the cut surface inside the glass samples. On the other hand, the O K-edge XANES spectra showed differences by measuring points for each glass sample, but the trends of those differences varied between the glass samples. The reason is that the molten raw glass with increased alumina concentration has a high viscosity, making it impossible to produce waste glasses with a uniform composition. The Na and Si K-edge spectra showed no differences between the coagulated layer and the inside of glass samples. In addition, the Ce L-edge XANES spectra confirmed that the Ce valence in the coagulated layer of glass samples was more oxidized compared to that in the inside of glass samples.
Yomogida, Takumi; Scaria, J.*; Fablet, L.*; Tokunaga, Kohei; Dei, Shuntaro; Higashi, Kotaro*; Kawamura, Naomi*; Takahashi, Yoshio*; Marsac, R.*
Chemical Communications, 61(91), p.17926 - 17929, 2025/11
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)This paper presents insights into the influence of magnetite stoichiometry (0 
R = Fe(II)/Fe(III) 0.5) on the surface reduction of U(VI) to U(V) and U(IV), as a key parameter controlling U redox speciation in natural settings. Although R can readily change due to the oxidation of structural Fe(II) or proton/ligand-promoted dissolution, prior studies have not quantified U(V) when assessing these effects. We employed U L
-edge HERFD-XANES spectroscopy to investigate the electronic structure of U on magnetite with varying stoichiometries and observed a peak splitting of U(V) on magnetite. Our results demonstrate the high stability of U(V) species under a wide range of conditions, and after 10 days on magnetite by the combination of MCR-ALS analysis. A key finding is that structural Fe(II), whose abundance depends on pH and redox conditions, plays a critical role for in the stabilization of U(V) on magnetite.
Fablet, L.*; P
drot, M.*; Choueikani, F.*; Kieffer, I.*; Proux, O.*; Pierson-Wickmann, A.-C.*; Cagniart, V.*; Yomogida, Takumi; Marsac, R.*
Environmental Science; Nano, 12(5), p.2815 - 2827, 2025/05
Times Cited Count：3 Percentile：75.05(Chemistry, Multidisciplinary)Nickel is an omnipresent trace element in the environment. Due to its high affinity for iron oxide nanoparticles, its elimination from soils and water by these nanoparticles represents an interesting strategy, specially by magnetites, which is naturally present in the environment. However, the interactions between Ni and magnetite are poorly understood, because of the difficulty to control the stoichiometry (Fe(II)-to-Fe(III) ratio) of magnetite. The behavior of Ni in the presence of magnetite nanoparticles with different stoichiometries, in aqueous solution and inert atmosphere, are probed by adsorption experiments and X-ray Absorption Spectroscopy. This study helps predicting the interactions between Ni and magnetite in environmental conditions, which can be used for the development of efficient remediation strategies.
Yomogida, Takumi; Takahashi, Yoshio*
Chikyu Kagaku, 59(1), p.1 - 10, 2025/03
X-ray absorption fine structure XAFS spectroscopy techniques, which are applicable to almost all elements, provide information on elemental valence and local structure with high elemental selectivity and high sensitivity. It has become an indispensable method in space geochemistry and environmental chemistry. This review presents examples of the application of fluorescence XAFS methods to elements that are difficult to detect by conventional methods, and examples where new chemical species information has been obtained by increasing the energy resolution of the X-ray fluorescence (XRF) detection system to obtain XAFS.
Nagai, Takayuki; Okamoto, Yoshihiro; Shibata, Daisuke*; Kojima, Kazuo*; Hasegawa, Takehiko*; Sato, Seiichi*; Fukaya, Akane*; Hatakeyama, Kiyoshi*
JAEA-Research 2024-014, 54 Pages, 2025/02
JAEA-Research-2024-014.pdf:7.02MB
XAFS measurements in the soft X-ray region are suitable for evaluating the chemical state of the surface layer of a measurement sample because the X-ray transmittance is low. In this study, the purpose of the study was to confirm the difference between the coagulated surface layer and the inside of the simulated waste glasses by measuring the K-edge of the glass constituent elements boron, oxygen, sodium, and silicon, and the L edge of the waste component cerium. As a result, the B K-edge XANES spectra showed that the proportion of B-O tetracoordinate sp structures (BO) on the surface layer of the coagulated glass samples was higher than that on the cut surface inside the glass samples, which is expected to improve the water resistance of the coagulated surface. On the other hand, the O K-edge XANES spectra suggested that the O abundance in the coagulated surface layer was lower than that in the cut surface inside the glass samples, and that alkali metal elements may be concentrated in the coagulated surface layer. However, no difference was observed in the Na K-edge XANES spectra between the coagulated surface layer and the cut surface, and no difference was observed in the Si K-edge XANES spectra between the solidified surface and the inside of glass samples. In addition, the Ce L-edge XANES spectra confirmed that the Ce valence in the surface layer of coagulated glass samples were oxidized compared to the inside of glass samples.
Yomogida, Takumi
Hoshako, 38(1), p.19 - 25, 2025/01
High-energy-resolution fluorescence detection-X-ray absorption near-edge structure (HERFD-XANES) spectroscopy has enabled us to discuss the electronic structure of actinide compounds in more detail than with conventional XANES spectroscopy. We are conducting research with the aim of contributing to the prediction of the migration behavior of trace actinide elements in the environment by performing actinide speciation in various environmental samples. In this paper, we introduce the content of the discussion of the electronic state of U from the perspective of basic science, which is important for advancing application of HERFD-XANES spectroscopy to environmental science.
Minowa, Kazuki*; Watanabe, So; Nakase, Masahiko*; Takahatake, Yoko; Miyazaki, Yasunori; Ban, Yasutoshi; Matsuura, Haruaki*
Nuclear Instruments and Methods in Physics Research B, 556, p.165496_1 - 165496_6, 2024/11
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)In this study, X-ray absorption near edge structure (XANES) spectral analysis and column experiments were used to verify the selectivity of rare earth (RE) ions by alkyl diamide amine (ADAAM) adsorbent. In addition, the interactions between the N atoms of ADAAM and RE ions were evaluated to determine whether any of the RE ions are a valid simulant for developing a mutual separation process for minor actinides (MAs) in highly radioactive liquid waste. It was confirmed that La and Ce interacted with the amine N atom of ADAAM and they showed a peak shift of the N-K edge XANES spectrum; this finding suggested that a soft interaction is an essential factor influencing ion selectivity. Therefore, the selection factor of RE ions by ADAAM adsorbent was similar to that of MAs. It was concluded that RE ions are reasonable species to simulate MAs.
Nagai, Takayuki; Okamoto, Yoshihiro; Yamagishi, Hirona*; Shibata, Daisuke*; Kojima, Kazuo*; Hasegawa, Takehiko*; Sato, Seiichi*; Fukaya, Akane*; Hatakeyama, Kiyoshi*
JAEA-Research 2023-004, 45 Pages, 2023/09
JAEA-Research-2023-004.pdf:6.07MB
The local structure of glass-forming elements and waste elements in borosilicate glasses varies with its chemical composition. In this study, simulated waste glass samples were prepared and the chemical state regarding boron (B), silicon (Si) and waste elements of iron (Fe), cesium (Cs) were estimated by using XAFS measurement in soft X-ray region. To understand the chemical stability of simulated waste glasses, XANES spectra of B K-edge, Fe L, L-edge, and Cs M
, M-edge were measured on the glass surface exposed to the leachate. As a result, it was found that the glass surface exposed to the leachate was changed and it was difficult to obtain a clear XANES spectrum. From the B K-edge XANES spectra on glass surfaces exposed to the leachate, an increase in three-coordination of B-O (BO) and a decrease in four-coordination of B-O (BO) were observed compared to the glass surfaces before immersion. The XANES spectra of Fe L, L-edge, and Cs M, M-edge show that as the exposure time in the leachate increases, the Cs present on the glass surface dissolves into the leachate. The XANES spectra of Si K-edge were measured on simulated waste glass surfaces before immersion, and it was confirmed that the change in XANES spectra given by NaO concentration had a larger effect than the waste component concentration.
Onuki, Toshihiko*; Ye, J.*; Kato, Tomoaki; Liu, J.; Takano, Masahide; Kozai, Naofumi; Utsunomiya, Satoshi*
Environmental Science; Processes & Impacts, 25(7), p.1204 - 1212, 2023/07
Times Cited Count：2 Percentile：13.15(Chemistry, Analytical)To elucidate chemical forms of Cs and I in microparticles produced via the Fukushima Daiichi Nuclear Power Plant accident and released into the atmosphere, we analyzed Cs and I in condensed vaporized particles (CVP) produced by melting experiments using nuclear fuel components containing CsI with concrete. CVPs consisted of many round particles containing Cs and I of diameters less than several tens of micrometers. Two kinds of particles were present: one containing large amounts of Cs and I, suggesting the presence of CsI, and the other containing small amounts of Cs and I with large Si contents. Most of CsI from both particles were dissolved in water. On the contrary, some fractions of Cs remained from the latter particles. These results suggest that Cs was incorporated in CVPs along with Si to form water low-soluble CVPs
Nagai, Takayuki
JAEA-Research 2022-014, 84 Pages, 2023/02
JAEA-Research-2022-014.pdf:22.26MB
Most of the simulated waste glasses used for physical property evaluation are processed into a shape suitable for the measurement method from glass gob obtained by slowly cooling molten glass to room temperature. However, the actual vitrified waste glass material is obtained by cooling and being coagulated the glass drained from the bottom of glass melter into the canister. In this study, Raman spectroscopy was performed on the coagulated surface of molten simulated waste glass in the depth direction to evaluate the state of the Si-O bridging structure near the coagulated glass surface. The Raman spectra measured from the surface to the depth direction near the surface of the glasses produced by several melting and coagulation conditions of molten simulated waste glass cullet in the air atmosphere, and it was confirmed that there were changes in these spectra. On the other hand, the raw material glass cullet and the surface of the glass solidified in argon gas atmosphere showed little change in the spectrum in the depth direction, and the Si-O bridging structure near the glass surface was similar. It was also confirmed that the spectrum change in the depth direction measurement was small for the cut surface of the glass, and that the change in the spectrum for the broken glass fracture surface was also small. For glasses with a large change in Raman spectra in the depth direction near the coagulated surface, the molten glass was cooled from the molten state to room temperature in a muffle furnace with air atmosphere. That is, the magnitude of the spectral change with respect to the depth direction depends on the time from the molten state to coagulation. In order to confirm the reason why the number of bridging oxygen in the Si-O bridging structure is small on the coagulated surface of glass, the XANES spectra of Si-K edge and Ce-L3 edge were measured by XAFS on the coagulated surface and the cutting face. As a result, the Si-K edge peak on the coagulated surface is
Sasaki, Yuji; Nakase, Masahiko*; Kaneko, Masashi; Kobayashi, Toru; Takeshita, Kenji*; Matsumiya, Masahiko*
Analytical Sciences, 5 Pages, 2023/00
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)We conducted three field researches on Ru-extraction, XANES, and DFT-calculation. The order of the distribution ratio, D(Ru), from acid, HCl 
H
SO
HNO
HClO, by MIDOA is studied by XANES spectra, which indicates the valency change of Ru in HCl media and supports the ion pairing extraction of anionic Ru ion and cationic MIDOA. The same extractant trend, NTAamide MIDOA IDOA, due to D values as the energy gap of HOMO and LUMO could be found by DFT calculation, which suggests that the reaction heat has a positive correlation with extractability for extractant.
Ln
O
(Ln = Gd, Er) solid solutionPham, V. M.*; Arima, Tatsumi*; Inagaki, Yaohiro*; Idemitsu, Kazuya*; Akiyama, Daisuke*; Nagai, Takayuki; Okamoto, Yoshihiro
Journal of Nuclear Materials, 556, p.153189_1 - 153189_9, 2021/12
Times Cited Count：2 Percentile：16.03(Materials Science, Multidisciplinary)The crystal structure change was evaluated for (1-x)UO-xLnO
(Ln=Gd or Er; x = 0 to 0.4) samples sintered at 1973 K for 8 h under Ar and Ar-10%H atmospheres. The effect of LnO doping on the crystal structure of UO was investigated by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). LnO doping into UO reduced the lattice parameter of UO-LnO solid solutions up to 40mol% LnO. The lattice parameters of these samples were comparable to those of stoichiometric (U,Ln)O
solid solutions, that is, the O/M ratios were close to 2.00. The U L-edge XANES analysis showed that higher U oxidation states of +5 or +6 formed, in addition to + 4. The EXAFS analysis indicated that the interatomic distances of U-O and Gd-O decreased with increasing x, whereas those of Er-O may not decrease monotonically.
Sugiura, Yuki; Tomura, Tsutomu*; Ishidera, Takamitsu; Doi, Reisuke; Francisco, P. C. M.; Shiwaku, Hideaki; Kobayashi, Toru; Matsumura, Daiju; Takahashi, Yoshio*; Tachi, Yukio
Journal of Radioanalytical and Nuclear Chemistry, 324(2), p.615 - 622, 2020/05
Times Cited Count：7 Percentile：49.14(Chemistry, Analytical)
-edge XANES to determination of U oxidation state in zirconTanaka, Kazuya; Takahashi, Yoshio*
Geochemical Journal, 53(5), p.329 - 331, 2019/00
Times Cited Count：1 Percentile：4.33(Geochemistry & Geophysics)We examined three natural zircon samples with different amounts of radiation doses using M-edge and L-edge U X-ray absorption near-edge structure (XANES). Analysis of XANES spectra at both M-edge and L-edge suggested that the oxidation state of U in the zircon sample with the highest radiation dose is tetravalent. The XANES spectra of the two other samples with lower radiation doses suggested a mixture of U(IV) and U(VI), while the possibility of U(V) was not excluded. This is the first work on the application of M-edge U XANES to the oxidation state of U in natural zircon.
-Edge X-ray absorption near edge structure spectraOta, Atsuyuki*; Tanaka, Kazuya; Tsuno, Hiroshi*
Journal of Physical Chemistry A, 122(41), p.8152 - 8161, 2018/10
Times Cited Count：1 Percentile：2.57(Chemistry, Physical)We investigated the application of L-edge XANES spectra to the local structural analysis of lanthanoids in aqueous solution, iron hydroxide, manganese dioxide, and calcium carbonate. For each lanthanoid, the full width at half maximum (FWHM) values of lanthanoid compounds roughly decreased with increasing coordination numbers. However, they did not strictly reflect the local coordination sphere of the lanthanoid complex, but were rather sensitive to their chemical forms. The relationship between the magnitude of the FWHM values was determined by the crystal field splitting or degeneracy of 5d orbitals. The systematic variation of FWHM can be explained by the ligand strength of the ligand molecules (-HO
, -O
, -OH, -CO
, -Cl, and -O) that cause the crystal field splitting. Therefore, the FWHM values of L-edge XANES of lanthanoid compounds may be more useful in speciation analysis rather than structural analysis such as EXAFS.
Shimada, Hiroyuki*; Fukao, Taishi*; Minami, Hirotake*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji
Journal of Chemical Physics, 141(5), p.055102_1 - 055102_8, 2014/08
Times Cited Count：23 Percentile：62.81(Chemistry, Physical)Konishi, Hiroyuki; Yamashita, Masato*; Uchida, Hitoshi*; Mizuki, Junichiro
Materials Transactions, 46(1), p.136 - 139, 2005/01
Times Cited Count：3 Percentile：32.20(Materials Science, Multidisciplinary)The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmosphere. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements, Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys, Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganite or magnetite. As a consequence, Ni negligibly interacts with Cl ions in the rust layer.
Yaita, Tsuyoshi; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Shimada, Asako*; Assefa, Z.*; Haire, R. G.*
Physica Scripta, T115, p.302 - 305, 2005/00
The structural parameter and the electronic structure of the complex between cerium and N,N'-dimethyl-N,N'-diphenylpyridine-2,6-carboxyamide(DMDPhPDA) was investigated by XAFS, photo luminescence and excitation spectra. The DMDPhPDA is one of the promising ligands for separation of trivalent actinides from lanthanides. The Ce-K XAFS spectra were measured at BL11XU of SPring-8. The bond distances between the carbonyl oxygens and cerium, and between the pyridyl nitrogen and cerium are 253pm and 264pm, respectively. The bond angle of the plane consisting of the two carbonyl oxygens and nitrogen with cerium was about 180 degree. This complex was a yellow color unique for the DMDPhPDA-lanthanide complexes. The photo absorption peak for the complex was extremely broad, and the peak position was at a higher wavenumber as compared with those for the other lanthanide complexes. The peak in the highest wavenumber of this band may be attributed to the transition between f and d orbitals, which are greatly influenced by the ligand field of the DMDPhPDA. The XANES spectrum of the cerium complex clearly showed that cerium was trivalent.
Yokoya, Akinari; Takakura, Kaoru*; Watanabe, Ritsuko; Akamatsu, Ken*; Ito, Takashi*
Radiation Research, 162(4), p.469 - 473, 2004/10
Times Cited Count：3 Percentile：9.72(Biology)X-ray absorption spectra from single crystals of 5-Bromouracil were measured with the transmission mode in the energy range from 13.41 to 13.50 keV using the linearly polarized synchrotron radiation (SR). A characteristic resonance structure, consisting of four peaks, was recognized in the spectra in the Br K-edge region. The intensities of these peaks were strongly dependent on the crystal rotation about the normal of the crystal b-c plane, which was set perpendicular to the X-ray beam direction. (SR X-rays are polarized in the horizontal plane.) Molecular orbital calculations indicate that these resonance peaks are associated with the transitions from the 1s electron of Br to the Br-C molecular antibonding orbitals and to a shape resonance. The observed anisotropy of each photoabsorption peak might originate from the angular dependences of these molecular orbitals.
