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Cs NMR chemical shift of clay minerals via machine learning and DFT-GIPAW calculationsOkubo, Takahiro*; Takei, Akihiro*; Tachi, Yukio; Fukatsu, Yuta; Deguchi, Kenzo*; Oki, Shinobu*; Shimizu, Tadashi*
Journal of Physical Chemistry A, 127(4), p.973 - 986, 2023/02
Times Cited Count：1 Percentile：56.86(Chemistry, Physical)The identification of adsorption sites of Cs on clay minerals has been studied in the fields of environmental chemistry. The nuclear magnetic resonance (NMR) experiments allow direct observations of the local structures of adsorbed Cs. The NMR parameters of Cs, derived from solid-state NMR experiments, are sensitive to the local neighboring structures of adsorbed Cs. However, determining the Cs positions from NMR data alone is difficult. This paper describes an approach for identifying the expected atomic positions of Cs adsorbed on clay minerals by combining machine learning (ML) with experimentally observed chemical shifts. A linear ridge regression model for ML is constructed from the smooth overlap of atomic positions descriptor and gauge-including projector augmented wave (GIPAW) ab initio data. The Cs chemical shifts can be instantaneously calculated from the Cs positions on any clay layers using ML. The inverse analysis from the ML model can derive the atomic positions from experimentally observed chemical shifts.
Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.
JAEA-Technology 2020-020, 73 Pages, 2021/03
JAEA-Technology-2020-020.pdf:8.26MB
The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.
Cs solid-state NMR and density functional theory calculationsOkubo, Takahiro*; Okamoto, Takuya*; Kawamura, Katsuyuki*; Gu
gan, R.*; Deguchi, Kenzo*; Oki, Shinobu*; Shimizu, Tadashi*; Tachi, Yukio; Iwadate, Yasuhiko*
Journal of Physical Chemistry A, 122(48), p.9326 - 9337, 2018/12
Times Cited Count：13 Percentile：60.51(Chemistry, Physical)The structures of Cs adsorption on montmorillonite were investigated by the nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra of Cs adsorbed on montmorillonite samples were measured under different Cs contents and relative humidity levels. NMR parameters were evaluated by the first principle calculations in order to identify the relationship between adsorbed Cs structures and NMR parameters. The comparisons between experimental and theoretical NMR spectra revealed that Cs is preferentially adsorbed at sites near Al for low Cs substituted montmorillonites, and that non-hydrated Cs present in partially Cs substituted samples, even after being hydrated under high relative humidity.
and Np
Ga
Haga, Yoshinori; Aoki, Dai*; Homma, Yoshiya*; Matsuda, Tatsuma; Ikeda, Shugo*; Sakai, Hironori; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 80(Suppl.A), p.SA109_1 - SA109_3, 2011/07
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)
Pr nuclear spin dynamics in PrPb; 
La NMR study in Pr
La
PbTokunaga, Yo; Sakai, Hironori; Chudo, Hiroyuki; Kambe, Shinsaku; Yasuoka, Hiroshi; Suzuki, Hiroyuki*; Walstedt, R. E.*; Homma, Yoshiya*; Aoki, Dai*; Shiokawa, Yoshinobu*
Physical Review B, 82(10), p.104401_1 - 104401_6, 2010/09
Times Cited Count：5 Percentile：26.3(Materials Science, Multidisciplinary)La NMR studies have been performed on PrPb substituted with 3% La. The temperature dependence of the local magnetic susceptibility around La ions has been extracted from the La Knight shift. These data show that the non-magnetic 
crystalline-electric-field (CEF) ground state (GS) is preserved even at the nearest neighboring Pr ions, although their CEF level scheme is slightly modified due to the La substitution. On the other hand, the temperature dependence of the nuclear spin-lattice relaxation rate 
is found to be well reproduced by assuming the same CEF level scheme over a wide temperature range. However, shows a strong upturn below 10 K, which is not expected from the non-magnetic CEF GS. We show that the low temperature anomaly can be quantitatively understood in terms of a cross-relaxation process between Pr and La nuclear spins.
Metoki, Naoto; Kaneko, Koji; Ikeda, Shugo*; Sakai, Hironori; Yamamoto, Etsuji; Haga, Yoshinori; Homma, Yoshiya*; Shiokawa, Yoshinobu*
IOP Conference Series; Materials Science and Engineering, 9, p.012088_1 - 012088_8, 2010/05
Times Cited Count：1 Percentile：54.48(Chemistry, Inorganic & Nuclear)Inelastic neutron scattering study has been carried out on US
. A clear crystalline electric field (CEF) peak has been observed at 7.4 meV, which is consistent with the level scheme obtained from susceptibility data assuming 5f
configuration. The CEF becomes very weak and broad, and a quasi-elastic response emerges above the characteristic temperature 
100 K. It indicates the crossover of the 5f character between localized and itinerant. A quasi-elastic response can be concluded as the hybridization effect of the 5f electrons with ligand p-electrons. Our study suggests that the crossover of the 5f character is the origin of the metal-insulator transition in US.
-US
Ikeda, Shugo*; Sakai, Hironori; Tateiwa, Naoyuki; Matsuda, Tatsuma; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu*; Ota, Yuki*; et al.
Journal of the Physical Society of Japan, 78(11), p.114704_1 - 114704_10, 2009/11
Times Cited Count：12 Percentile：59(Physics, Multidisciplinary)
; X-ray magnetic circular dichroism studyOkane, Tetsuo; Okochi, Takuo*; Inami, Toshiya; Takeda, Yukiharu; Fujimori, Shinichi; Kawamura, Naomi*; Suzuki, Motohiro*; Tsutsui, Satoshi*; Yamagami, Hiroshi; Fujimori, Atsushi; et al.
Physical Review B, 80(10), p.104419_1 - 104419_7, 2009/09
Times Cited Count：6 Percentile：29.51(Materials Science, Multidisciplinary)
Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Chudo, Hiroyuki; Yasuoka, Hiroshi; Matsuda, Tatsuma; Haga, Yoshinori; Ikeda, Shugo; Nakamura, Akio; Yamamoto, Etsuji; et al.
Journal of Nuclear Materials, 385(1), p.1 - 3, 2009/03
Times Cited Count：1 Percentile：10.22(Materials Science, Multidisciplinary)In 5f-electron systems, exotic magnetism and unconventional superconductivity appear at low temperatures owing to strong electron correlations and orbital degeneracy. For example, we have investigated the unconventional superconducting states of recently synthesized NpPdAl (
=5K) and PuRhGa (=9K) in terms of both macroscopic (staticsusceptibility, specific heat, resistivity) and microscopic (NMR) probes. The relation between magnetic fluctuations and unconventional superconductivity in f-electron systems is also discussed. Another exciting topic concerns the series AnO (An; U, Np, Pu, Am). Besides the importance of AnO as a nuclear fuel, the magnetic properties of these compounds at low temperatures are particularly interesting. On the basis of 
O-NMR studies, multipolar ordered states have been identified in UO (dipolar + quadrupolar ordering) and NpO (quadrupolar + octupolar ordering), in contrast with the non-magnetic ground state of PuO.
P-NMR study of hyperfine interactions and magnetic fluctuations in the neptunium-based filled skutterudite NpFe
P
Tokunaga, Yo; Kambe, Shinsaku; Sakai, Hironori; Chudo, Hiroyuki; Matsuda, Tatsuma; Haga, Yoshinori; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Shiokawa, Yoshinobu*; et al.
Physical Review B, 79(5), p.054420_1 - 054420_7, 2009/02
Times Cited Count：5 Percentile：25.59(Materials Science, Multidisciplinary)P-NMR measurements have been performed on a single crystal of the neptunium-based filled skutterudite NpFeP. We have observed transferred hyperfine interactions at the P sites, which lead to an estimate of the local spin density in the P 3
orbitals. It is shown that a fraction of the Np 5
spin moments is transferred mostly into the P 3 orbitals extending toward the inside of a P-cage. The weak hybridization between Np 5 and P 3 orbitals suggests a localized character for Np 5 electrons. We have also measured the field and temperature dependences of the nuclear spin-lattice relaxation rate (). The data reveal that the low-energy spin fluctuations of Np 5 spin moments are strongly suppressed by applied fields over a relatively wide temperature range. The present NMR results demonstrate that the negative magnetoresistance comes from a reduction of the magnetic scattering from Np 5 spin moments by an applied field.
Tokunaga, Yo; Suzuki, Hiroyuki*; Sakai, Hironori; Chudo, Hiroyuki; Kambe, Shinsaku; Yasuoka, Hiroshi; Homma, Yoshiya*; Aoki, Dai*; Shiokawa, Yoshinobu*
Journal of Physics; Conference Series, 150, p.042211_1 - 042211_4, 2009/00
Times Cited Count：2 Percentile：74.15(Thermodynamics)The first La-NMR measurement has been carried out on a La dilute system of PrPb. We have succeeded to detect La-NMR signal on a powder sample of PrLaPb and extracted the temperature dependence of the Knight shift 
in a temperature range between 1.5 and 220 K. has been found to maintain a linear relation with the bulk-susceptibility 
in wide temperature range, except for a small deviation in the temperature region below 6 K. The slopes of the 
vs 
plots yield for the hyperfine coupling constants 
the value 375 Oe/
. From the NMR results, we discuss the effect of the La substitutions on microscopic magnetic properties of PrPb.
Al (An = U, Np)Haga, Yoshinori; Aoki, Dai*; Homma, Yoshiya*; Ikeda, Shugo; Matsuda, Tatsuma; Yamamoto, Etsuji; Sakai, Hironori; Tateiwa, Naoyuki; Dung, N. D.*; Nakamura, Akio; et al.
Journal of Alloys and Compounds, 464(1-2), p.47 - 50, 2008/09
Times Cited Count：19 Percentile：66.95(Chemistry, Physical)
Al NMR evidence for the strong-coupling 
-wave superconductivity in NpPdAlChudo, Hiroyuki; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Aoki, Dai*; Homma, Yoshiya*; Shiokawa, Yoshinobu*; Haga, Yoshinori; Ikeda, Shugo*; Matsuda, Tatsuma; et al.
Journal of the Physical Society of Japan, 77(8), p.083702_1 - 083702_4, 2008/08
Times Cited Count：24 Percentile：97.52(Physics, Multidisciplinary)We present Al NMR studies for a single crystal of the newly developed superconductor NpPdAl (
K). In the superconducting state, the Al NMR spectrum shifts to lower frequencies owing to a decrease of the spin part of the Knight shift, and exhibits broadening characteristic of the local field distribution associated with a vortex lattice. We have also found that the Al nuclear spin-lattice relaxation rate () decreases just below with no coherence peak and shows 
behavior at low temperatures. The observed temperature dependences of the Knight shift and in general accord with those assuming a line-node superconducting gap with the gap value of 
. Therefore, the present NMR data provides evidence for strong-coupling -wave superconductivity in NpPdAl.
Tokunaga, Yo; Homma, Yoshiya*; Kambe, Shinsaku; Aoki, Dai*; Sakai, Hironori; Chudo, Hiroyuki; Ikushima, Kenji*; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu*; et al.
Journal of Optoelectronics and Advanced Materials, 10(7), p.1663 - 1665, 2008/07
Multipolar degrees of freedom characteristic of -electrons bring rich and complex physics to rare-earth and actinide compounds. In the present work, we demonstrate that microscopic investigation of multipole order parameters is also possible by means of NMR through the hyperfine interactions. Our O NMR study performed on a single crystal of NpO provide definitive support for the proposed longitudinal triple-
type antiferro-octupolar ordering below 
26 K. We shall also provide our O NMR results on UO and PuO. The microscopic NMR clearly indicates the different nature of the magnetic ground states among three actinide dioxides.
-USIkeda, Shugo; Sakai, Hironori; Matsuda, Tatsuma; Tateiwa, Naoyuki; Nakamura, Akio; Yamamoto, Etsuji; Aoki, Dai*; Homma, Yoshiya*; Shiokawa, Yoshinobu*; Hedo, Masato*; et al.
Physica B; Condensed Matter, 403(5-9), p.893 - 894, 2008/04
Times Cited Count：6 Percentile：30.34(Physics, Condensed Matter)Single crystals of paramagnetic semiconductor -US with the orthorhombic (
) crystal structure were grown by chemical transport method. We measured the electrical resistivity 
under high pressure, and magnetization. With increasing pressure, the temperature dependence of approaches to semimetallic behavior and a kink anomaly appears at 
. shifts to higher temperature with increasing pressure. From the comparison with ferromagnetic semimetal UTeS having the same crystal structure, it seems that is a ferromagnetic transition.
by neutron diffractionJonen, Shintaro; Metoki, Naoto; Yamamoto, Etsuji; Homma, Yoshiya*; Aoki, Dai*; Shiokawa, Yoshinobu*; Onuki, Yoshichika
Journal of Alloys and Compounds, 448(1-2), p.84 - 88, 2008/01
Times Cited Count：1 Percentile：12.99(Chemistry, Physical)The magnetic structure of NpPtGa
was investigated by neutron diffraction. NpPtGa exhibits an A-type antiferromagnetic structure with propagation vector 
= (0 0 1/2) below 
= 26 K. The estimated Np magnetic moment is 0.38(5) 
, and it is oriented parallel to the 
100
direction. This small moment would be consistent with the large 
= 123 mJ/(K
mol), indicative of the heavy fermion nature. The field-induced anomaly in the magnetic susceptibility is clarified to be a signature for an antiferromagnetic domain change between multi-domains to single-domain states.
P-NMR study of the neptunium-based filled-skutterudite NpFe
PTokunaga, Yo; Aoki, Dai*; Homma, Yoshiya*; Sakai, Hironori; Chudo, Hiroyuki; Kambe, Shinsaku; Matsuda, Tatsuma; Ikeda, Shugo; Yamamoto, Etsuji; Nakamura, Akio; et al.
Journal of the Physical Society of Japan, 77(Suppl.A), p.211 - 213, 2008/00
Times Cited Count：3 Percentile：27.6(Physics, Multidisciplinary)P-NMR measurements have been performed on a single crystal of NpFeP which is the first crystallized transuranium filled-skutterudite compound. The field-orientation dependence of the hyperfine interaction has been measured using the single crystal, and the results compared with those obtained previously in isostructural compounds UFeP and PrFeP. We have also measured the field and temperature dependence of the nuclear spin-lattice relaxation rate in several fields between 1.8 and 8 T at temperatures between 4.2 and 300 K. The results are discussed on the basis of a localized picture for the 5f electrons.
Ikeda, Shugo*; Sakai, Hironori; Matsuda, Tatsuma; Tateiwa, Naoyuki; Aoki, Dai*; Homma, Yoshiya*; Nakamura, Akio; Yamamoto, Etsuji; Shiokawa, Yoshinobu*; Hedo, Masato*; et al.
Journal of the Physical Society of Japan, 77(Suppl.A), p.359 - 361, 2008/00
Times Cited Count：1 Percentile：11.66(Physics, Multidisciplinary)The ferromagnet UTeS was studied by measurement the resistivity under high pressure. The Curie temperature 
rapidly increases from 87 K to 166 Kat 8 GPa. The result suggests that there is a correlation between the electrical conductivity and magnetic transition temperature, implying the strong hybridization.
AlAoki, Dai*; Haga, Yoshinori; Matsuda, Tatsuma; Tateiwa, Naoyuki; Ikeda, Shugo*; Homma, Yoshiya*; Sakai, Hironori; Shiokawa, Yoshinobu*; Yamamoto, Etsuji; Nakamura, Akio; et al.
Journal of the Physical Society of Japan, 77(Suppl.A), p.159 - 164, 2008/00
Times Cited Count：3 Percentile：27.6(Physics, Multidisciplinary)Superconducting properties are investigated on the new neptunium-based superconductor NpPdAl. The large electronic specific heat, anisotropy of magnetic as well as superconducting properties and strong paramagnetic effect implies spin-singlet pairing with anisotropic superconducting gap.
Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.
Journal of Physics and Chemistry of Solids, 68(11), p.2103 - 2106, 2007/11
Times Cited Count：1 Percentile：7.46(Chemistry, Multidisciplinary)A lot of attention is currently focused on Pu-based superconductors. These systems have relatively high superconducting (SC) transition temperatures, 
18 K for PuCoGa and 9 K for PuRhGa. Both compounds crystallize in the tetragonal HoCoGa (115) structure, which is well known for the heavy-fermion SC systems Ce
In (=Co, Rh, Ir)with 
2 K at most. Recently, NMR and NQR experiments have been reported for PuCoGa by Curro et al. and for PuRhGa by our group. In both cases, measurements of 
using NQR have revealed that the Pu115 superconductors show unconventional superconductivity with an anisotropic gap. Now we have measured the more detailed data of for NQR lines in PuRhGa, especially focusing on the low-lying magnetic excitation in the normal state. From the viewpoint of spin-fluctuations, we will discuss the difference between PuRhGa and PuCoGa and between superconducting Pu115 and non-superconducting An115 series.
