Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ota, Kyugo*; Matsumoto, Yuji*; Watabe, Yuki*; Kaneko, Koji; Tabata, Chihiro; Haga, Yoshinori
New Physics; Sae Mulli, 73(12), p.1170 - 1173, 2023/12
We have performed the neutron scattering study of antiferromagnet UPtAl with the honeycomb lattice to determine the magnetic structure. UPtAl exhibits two phase transitions at = 9 K and = 26 K. In phase I at , the magnetic reflections described by a propagation vector = (1/3, 0, 0) were observed. In phase II at , magnetic reflections of = (1/3, 0, 0) and = (1/2, 0, 0) were observed and the magnetic reflection intensity of = (1/3, 0, 0) is weak but finite. The hysteresis in the temperature dependent intensities is observed across the phase transition at , suggesting that the transition at is of first order.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Suzuki, Hideya*
Journal of Nuclear Science and Technology, 11 Pages, 2023/11
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)The mutual separation of Am and Cm is conducted using an alkyl-diamide amine (ADAAM) extractant. ADAAM exhibits extremely high separation factor with respect to Am and Cm separation (5.9) in a nitric acid--dodecane system. The batch-wise multistage extractions are performed using a system containing 0.2 M ADAAM and 1.5 M nitric acid. In this multistage extraction, an organic solvent give 96.5% and 1.06% yields of Am and Cm. After the mutual separation of Am and Cm, an additional extraction step is included to reduce the volumes of these aqueous and organic phases. Taking these steps, Am and Cm can be recovered in just two or three stages in the aqueous phases.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Kinoshita, Ryoma; Matsumiya, Masahiko*; Shinoku, Kota*; Shiroishi, Hidenobu*
Analytical Sciences, 39(9), p.1575 - 1583, 2023/09
Times Cited Count:0 Percentile:0(Chemistry, Analytical)Extraction of Rh from HCl can be performed by NTAamide(C6) (hexahexyl-nitrilotriacetamide) and other related compounds into n-dodecane. We use ion-pair extraction of anionic species of Rh-chloride and protonated extractant. Rh behave as anion in hydrochloric acid and the tertiary nitrogen atom in extractant may be protonated to produce the quaternary amine in acidic condition. From the present work, the maximum distribution ratio of Rh(III) is 16. The D(Rh) values are changeable during preparation of the aqueous solutions because different Rh-Cl-HO complexes are formed in HCl media and show the slow exchange rate between Cl and HO. Using the UV spectrum, Rh-chloride solution having the peak of spectrum at 504 nm can be extracted effectively, where RhCl(HO) and RhCl(HO) exist mainly from DFT calculation. Stoichiometry of one-one complex of Rh and NTAamide is obtained from slope analysis, and 85 mM of concentrated Rh ion can be extracted.
Sasaki, Yuji; Nakase, Masahiko*; Kaneko, Masashi; Kobayashi, Toru; Takeshita, Kenji*; Matsumiya, Masahiko*
Analytical Sciences, 5 Pages, 2023/00
Times Cited Count:0 Percentile:0(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 HSO 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.
Nomizu, Daiki; Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Katsuta, Shoichi*
Journal of Radioanalytical and Nuclear Chemistry, 331(3), p.1483 - 1493, 2022/03
Times Cited Count:4 Percentile:68.71(Chemistry, Analytical)We studied the successive formation of water soluble DGA (diglycolamide) and DOODA (dioxaoctanediamide) for the mutual separation of Ln in this extraction system. TODGA (tetraoctyl-diglycolamide) and DOODA(C8) (tetraoctyl-dioxaoctanediamide) have the opposite trend to extract light and heavy Ln through Ln-patterns. Metal-complexes of two folding Ln ions with water-soluble DOODA and three folding with DGA are found and their observed formation constants are calculated. The suitable separation condition (aqueous phase: 30 mM DOODA(C2) in 1 M nitric acid, organic phase: 0.1 M TODGA in n-dodecane) of multi-stage extraction (10 10) is conducted. From the present work, it is clear that La, Pr and Nd are mainly present in aqueous phase, instead Sm-Dy exist in the organic phase.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Separation Science and Technology, 57(16), p.2543 - 2553, 2022/00
Times Cited Count:3 Percentile:29.84(Chemistry, Multidisciplinary)The mutual separation of actinides (An) from lanthanides (Ln) using the masking agent of DTPA (diethylenetriamine-pentaacetic acid) or DTBA (diethylenetriamine-triacetic acid-bis(diethylacetamide)) in the aqueous phase through DGA extraction, referring TALSPEAK method, is focused. We investigate to obtain the same separation performance using commercially available DTPA on that using DTBA. In this work, we select lactic acid (LA) of pH buffer from 10 organic acids and ethylenediamine (ED) for the pH adjustment. Almost the same D and SF values are obtained among the conditions: TODGA-DTPA-LA-NaOH, TODGA-DTPA-LA-ED, and TODGA-DTBA-LA. The experimental results using batchwise multi-stage extractions show the average yields of Ln (La to Gd) and Am to be 3.73 and 98.1% in the aqueous phase using DGA-DTPA-LA-ED, to be 3.1 and 97.0% using DGA-DTPA-LA-NaOH, and to be 1.61 and 98.7% using DGA-DTBA-LA.
Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Solvent Extraction and Ion Exchange, 40(6), p.620 - 640, 2022/00
Times Cited Count:1 Percentile:14.86(Chemistry, Multidisciplinary)Owing to the chemical behavior of trivalent lanthanide and actinide ions with similar ionic radii, realizing this separation is still challenging. All lanthanides, Am, and Cm can be extracted using diglycolamide (DGA), and relatively high An/Ln separation efficiencies have been obtained using diethylenetriamine-triacetic-bisamide (DTBA). To improve the previous results as well as the separation conditions, we used organic acids for pH adjustment. The advantages of this modification included low HNO, DTBA concentrations and pH stability owing to the addition of lactic acid. Under these modified conditions, the recovery rates observed were as follows: 97.1% for Nd with the co-existence of 1.59% Am in organic phase, and 98.4% for Am with the co-existence of 2.95% Nd in aqueous phase.
Kaneko, Masashi; Sasaki, Yuji; Wada, Eriko*; Nakase, Masahiko*; Takeshita, Kenji*
Chemistry Letters, 50(10), p.1765 - 1769, 2021/10
Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)Density functional theory calculation is applied to predict the stability constants for Eu and Am complexes in aqueous solution for molecular modelling of novel separation agents for minor actinides over lanthanides. Logarithm of experimental stability constants correlates with calculated complex formation enthalpies with high reproducibility (R 0.98). Prediction of stability constants of novel chelates is demonstrated and indicates a potential availability of the derivatives of diethylenetriaminepentaacetic acid type chelate in acidic condition and enhancement of Am selectivity over Eu.
Kaneko, Masashi; Sasaki, Yuji; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 58(5), p.515 - 526, 2021/05
Times Cited Count:3 Percentile:35.51(Nuclear Science & Technology)Density-functional theory calculations were applied to molecular structure and complex formation reaction modelings of metal ion complexes with diethylenetriaminepentaacetic acid (DTPA) and its bisamide (DTPABA) chelates to understand the metal ions selectivity between Am and Eu. The calculated complexes with DTPA and DTPABA chelates reproduced the coordination geometries of experimental crystal structures. Calculated Gibbs free energies of the complex formation reactions indicated that Am ion forms higher stable complexes with both chelates than Eu ion, being consistent with the experimental results. The higher Am selectivity over Eu was suggested to originate in the larger bond overlap between Am 5f-orbital and N 2s, 2p-orbital. This mean that the covalent contribution between metal ion and donor atoms differentiates the complex formation stabilities, leading to the Am/Eu selectivity. We expect that this study contributes to systematize the origin of metal ions selectivity and to accelerate novel ligands exploration.
Sasaki, Yuji; Morita, Keisuke; Ito, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Takahashi, Yuya*; Kaneko, Masaaki*; Omori, Takashi*; Asano, Kazuhito*
Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09
no abstracts in English
Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*
Solvent Extraction Research and Development, Japan, 24(2), p.113 - 122, 2017/06
The solvent extraction of Se, Zr, Pd, and Cs from nitric acid into 1-octanol (OC) and dodecane has been performed. These elements include long-lived radionuclides in spent nuclear fuels, so a simple separation method is indispensable for the development of the treatment of high-level liquid radioactive waste. It was found that Se can be extracted using phenylenediamine, Zr can be extracted using tetraoctyl diglycolamide and di-2-ethylhexyl phosphoric acid, and Pd can be extracted using (methylimino)bis(dioctylacetamide) and hexaoctylnitrilotriacetamide. These elements can be recovered in over 90% yield by these extractants from nitric acid into OC. A distribution ratio of Cs of greater than 1 can be obtained using di-t-butyldibenzo-18-crown-6. It is clear that 90% recovery of Cs can be achieved using an extraction solvent with ten times the volume of the aqueous phase.
Kaneko, Makoto*; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota*; Kawamoto, Yuji*; Yamasaki, Shinya*; Nakamatsu, Yuki*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; et al.
Frontiers in Energy Research (Internet), 3, p.37_1 - 37_10, 2015/09
The mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs migration in Fukushima.
Tsutsui, Satoshi; Kaneko, Koji; Miyazaki, Ryoichi*; Higashinaka, Ryuji*; Aoki, Yuji*; Kobayashi, Riki*; Wakimoto, Shuichi; Baron, A. Q. R.*; Sugawara, Hitoshi*; Sato, Hideyuki*
JPS Conference Proceedings (Internet), 3, p.011060_1 - 011060_5, 2014/06
Takeda, Masayasu; Yamazaki, Dai; Soyama, Kazuhiko; Maruyama, Ryuji; Hayashida, Hirotoshi; Asaoka, Hidehito; Yamazaki, Tatsuya; Kubota, Masato; Aizawa, Kazuya; Arai, Masatoshi; et al.
Chinese Journal of Physics, 50(2), p.161 - 170, 2012/04
Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Metoki, Naoto; Raymond, S.*; Masson, M.-A.*; Flouquet, J.*; Sugawara, Hitoshi*; Aoki, Yuji*; et al.
Physica B; Condensed Matter, 385-386(Part 1), p.82 - 84, 2006/11
Times Cited Count:3 Percentile:17.99(Physics, Condensed Matter)We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOsSb. The observed excitation clearly softens at a wave vector Q=(1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at Q=(1,0,0) is smaller than that around the zone center. This result directly evidences that this excitonic behavior is derived mainly from nonmagnetic quadrupolar interactions. Furthermore, the narrowing of the linewidths of the excitations below the superconducting transition temperature indicates the close connection between the superconductivity and the excitons.
Ando, Masaki; Kawasaki, Kenji*; Okajima, Shigeaki; Fukushima, Masahiro; Matsuura, Yutaka*; Kaneko, Yuji*
JAERI-Research 2005-026, 39 Pages, 2005/09
U Doppler effect measurements in moderated neutron spectra (uranium fuel and MOX simulated fuel) were carried out using FCA for the purpose of contributing to the improvement in prediction accuracy for Doppler coefficient in LWR. In the mockup cores for MOX fuel, the measurements were performed in different neutron spectra, where the voidage of moderator material was varied systematically. The experimental data were obtained using cylindrical uranium samples with different outer diameter up to 800C. Analyses were performed using a standard code system designed to analyze fast reactor mock-up experiments at FCA with the use of the JENDL-3.2 library. The results of the analyses showed that the calculation accuracy did not depend on the types of the core fuel or the Doppler samples. The calculated values agreed with the experimental ones within the experimental error. Any dependency of the prediction accuracy on the neutron spectra was not observed in the MOX simulated fuel cores.
Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Metoki, Naoto; Raymond, S.*; Masson, M.-A.*; Flouquet, J.*; Sugawara, Hitoshi*; Aoki, Yuji*; et al.
Physical Review Letters, 95(10), p.107003_1 - 107003_4, 2005/09
Times Cited Count:96 Percentile:92.15(Physics, Multidisciplinary)We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOsSb. The observed excitation clearly softens at a wave vector = (1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at = (1,0,0) is smaller than that around the zone center. This result directly evidences that this excitonic behavior is derived mainly from nonmagnetic quadrupolar interactions. Furthermore, the narrowing of the linewidths of the excitations below the superconducting transition temperature indicates the close connection between the superconductivity and the excitons.
Raymond, S.*; Flouquet, J.*; Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Metoki, Naoto; Sugawara, Hitoshi*; Aoki, Yuji*; Sato, Hideyuki*
Physica B; Condensed Matter, 359-361, p.898 - 900, 2005/06
Times Cited Count:2 Percentile:11.66(Physics, Condensed Matter)The low lying magnetic excitations of the unconventional heavy fermion superconductor PrOsSb were studied by inelastic neutron scattering on single crystalline sample. The crystal field excitation first evidenced at 0.7 meV on powder samples is found to have a minimum of energy at the zone boundary corresponding to the wavevector of antiferro-quadrupolar instability. The evolution of the magnetic excitation spectrum under magnetic field confirms the singlet ground state.
Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Araki, Shingo; Metoki, Naoto; Sugawara, Hitoshi*; Aoki, Yuji*; Sato, Hideyuki*
Journal of the Physical Society of Japan, 73(6), p.1438 - 1441, 2004/06
Times Cited Count:64 Percentile:87.39(Physics, Multidisciplinary)no abstracts in English
Metoki, Naoto; Kaneko, Koji; Araki, Shingo; Kogi, Masafumi*; Iwasa, Kazuaki*; Kuwahara, Keitaro*; Bernhoeft, N.*; Mignot, J.-M.*; Gukasov, A.*; Sato, Hideyuki*; et al.
Journal of Magnetism and Magnetic Materials, 272-276(Suppl.), p.e91 - e92, 2004/05
Times Cited Count:1 Percentile:7.12(Materials Science, Multidisciplinary)no abstracts in English