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Journal Articles

Crystallographic and/or magnetic properties of neutral and cationic uranium(IV) sandwiched phthalocyanine complexes

Tabata, Chihiro; Watanabe, Hirohito*; Shirasaki, Kenji*; Sunaga, Ayaki*; Fukuda, Takamitsu*; Li, D.*; Yamamura, Tomoo*

Journal of Molecular Structure, 1277, p.134870_1 - 134870_8, 2023/04

 Times Cited Count:0 Percentile:0(Chemistry, Physical)

Neutral and cationic U(IV) sandwiched phthalocyanine (Pc) complexes were prepared. The neutral species, UPc$$_{2}$$, was obtained by the reaction of UCl$$_{4}$$] and phthalonitrile, and the [UPc$$_{2}$$][BF$$_{4}$$] crystals were grown by electrolysis. The structures of the complexes were determined crystallographically. A U(IV) ion has two $$5f$$ electrons, which carry a magnetic moment localized at the U sites, making the complex magnetically active. The magnetic susceptibility measurement of UPc$$_{2}$$ revealed that the system was paramagnetic with local magnetic moments down to 2 K, but these magnetic moments were suppressed, possibly by a ligand field effect. The paramagnetism was also confirmed by the magnetization curve without hysteresis. The cationic complex, [UPc$$_{2}$$][BF$$_{4}$$]] crystalized in a tetragonal structure with the space group $$P4nc$$, in which the UPc$$_{2}$$ molecules stacked along the tetragonal $$c$$-axis. The structure was similar to that of [LnPc$$_{2}$$][BF$$_{4}$$]], but with distinct disorder in the stacking plane. The stabilities of the crystal and molecular structures and the electronic configurations of UPc$$_{2}$$ and [UPc$$_{2}$$][BF$$_{4}$$]] were evaluated via the $$ab initio$$ calculations that included the multiconfigurational nature of the actinide element.

Journal Articles

Influence of additives on low-temperature hydrothermal synthesis of UO$$_{2+x}$$ and ThO$$_2$$

Tabata, Chihiro; Shirasaki, Kenji*; Sakai, Hironori; Sunaga, Ayaki*; Li, D.*; Konaka, Mariko*; Yamamura, Tomoo*

CrystEngComm (Internet), 24(19), p.3637 - 3648, 2022/05

 Times Cited Count:2 Percentile:65.9(Chemistry, Multidisciplinary)

Journal Articles

Homogeneity of (U, $$M$$)O$$_2$$ ($$M$$ = Th, Np) prepared by supercritical hydrothermal synthesis

Shirasaki, Kenji*; Tabata, Chihiro*; Sunaga, Ayaki*; Sakai, Hironori; Li, D.*; Konaka, Mariko*; Yamamura, Tomoo*

Journal of Nuclear Materials, 563, p.153608_1 - 153608_11, 2022/05

 Times Cited Count:2 Percentile:68.58(Materials Science, Multidisciplinary)

We focused on the direct synthesis of (U, $$M$$)O$$_2$$ solid solution ($$M$$=Th, Np) by extending our recent progress in hydrothermal synthesis with additives. The homogeneity of the (U, $$M$$)O$$_2$$ ($$M$$ = Th, Np) systems prepared by supercritical hydrothermal reactions was investigated through crystallographic analysis based on Vegard's law, and the $$^{23}$$Na nuclear magnetic resonance (NMR) measurement of (U, Np, Na)O$$_2$$ solid solutions. Our experimental and analytical results revealed that (i) an optimal additive is ammonium carbonate and starting uranium valence is IV in the case of (U, Th)O$$_{2+x}$$, and (ii) an optimal additive is ethanol and starting uranium valence is VI in the case of (U, Np)O$$_{2+x}$$, for producing the homogeneous solid solutions by hydrothermal synthesis.

Journal Articles

Supercritical hydrothermal synthesis of UO$$_{2+x}$$; Stoichiometry, crystal shape and size, and homogeneity observed using $$^{23}$$Na-NMR spectroscopy of (U, Na)O$$_{2+x}$$

Tabata, Chihiro*; Shirasaki, Kenji*; Sunaga, Ayaki*; Sakai, Hironori; Li, D.*; Konaka, Mariko*; Yamamura, Tomoo*

CrystEngComm (Internet), 23(48), p.8660 - 8672, 2021/12

 Times Cited Count:5 Percentile:72.31(Chemistry, Multidisciplinary)

The hydrothermal synthesis of pure uranium dioxide under supercritical water (SCW) conditions was investigated. The nonstoichiometry, crystallite size and morphology of the UO$$_{2+x}$$ particles were investigated. The SCW hydrothermal synthesis may be a promising method for producing homogeneous UO$$_{2+x}$$ and its solid solutions with well-defined nonstoichiometries ($$x$$), shapes, and sizes.

Journal Articles

Crystal structure and magnetic properties of new ternary uranium compound U$$_3$$TiBi$$_9$$

Motoyama, Gaku*; Haga, Yoshinori; Yamaguchi, Akira*; Kawasaki, Ikuto*; Sumiyama, Akihiko*; Yamamura, Tomoo*

Progress in Nuclear Science and Technology (Internet), 5, p.157 - 160, 2018/11

Journal Articles

Extended X-ray absorption fine structure study on gel/liquid extraction of f-block elements

Nakase, Masahiko*; Kobayashi, Toru; Shiwaku, Hideaki; Kawamura, Takuya*; Takeshita, Kenji*; Yamamura, Tomoo*; Yaita, Tsuyoshi

Progress in Nuclear Science and Technology (Internet), 5, p.56 - 60, 2018/11

Gel/liquid extraction was investigated to achieve selective separation of trivalent actinides over lanthanides. In this study, thermosensitive hydrogel including N,N,N',N'-tetraallylpyridine-2,6-dicarboxamine (PDA) was synthesized, and its complexation with lanthanide was investigated by extended X-ray absorption fine structure experiments at SPring-8. The radial structure functions (RSF) of solution with gels with and without ligands at different temperatures showed slight differences. As the temperature increased, the RSF decreased owing to the increase in thermal vibration, but PDA-gel showed a shift in the first peak toward the shorter direction. This shift was attributed to the change in stoichiometry of PDA-Ln(III) complexes or coordination number of water molecules affected by the change of conformation of polymer chains and the hydrophilic/hydrophobic properties in the hydrogel.

Journal Articles

Report on International Conference; Actinides 2017

Haga, Yoshinori; Yamamura, Tomoo*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 60(3), P. 181, 2018/03

no abstracts in English

Journal Articles

ScPd$$_2$$Al$$_3$$; New polymorphic phase in Al-Pd-Sc system

Pospisil, J.; Haga, Yoshinori; Nakajima, Kunihisa; Ishikawa, Norito; C$'i$sa$v{r}$ov$'a$, I.*; Tateiwa, Naoyuki; Yamamoto, Etsuji; Yamamura, Tomoo*

Solid State Communications, 268, p.12 - 14, 2017/12

 Times Cited Count:0 Percentile:0(Physics, Condensed Matter)

Journal Articles

Magnetoresistance and Hall effect of antiferromagnetic uranium compound URhIn$$_5$$

Haga, Yoshinori; Matsumoto, Yuji*; Pospisil, J.; Tateiwa, Naoyuki; Yamamoto, Etsuji; Yamamura, Tomoo*; Fisk, Z.*

Journal of Physics; Conference Series, 807(1), p.012015_1 - 012015_4, 2017/04

 Times Cited Count:1 Percentile:35.79

Journal Articles

Switching of magnetic ground states across the UIr$$_{1-x}$$Rh$$_x$$Ge alloy system

Pospisil, J.; Haga, Yoshinori; Kambe, Shinsaku; Tokunaga, Yo; Tateiwa, Naoyuki; Aoki, Dai*; Honda, Fuminori*; Nakamura, Ai*; Homma, Yoshiya*; Yamamoto, Etsuji; et al.

Physical Review B, 95(15), p.155138_1 - 155138_15, 2017/04

 Times Cited Count:13 Percentile:55.46(Materials Science, Multidisciplinary)

Journal Articles

Fermi surface of ThRu$$_{2}$$Si$$_{2}$$ as a reference to the strongly correlated isostructural metals investigated by quantum oscillations

Matsumoto, Yuji*; Haga, Yoshinori; Tateiwa, Naoyuki; Aoki, Haruyoshi*; Kimura, Noriaki*; Yamamura, Tomoo*; Yamamoto, Etsuji; Matsuda, Tatsuma*; Fisk, Z.*; Yamagami, Hiroshi*

Journal of the Physical Society of Japan, 85(10), p.104709_1 - 104709_7, 2016/10

 Times Cited Count:2 Percentile:20.8(Physics, Multidisciplinary)

Journal Articles

Properties and collapse of the ferromagnetism in UCo$$_{1-x}$$Ru$$_{x}$$Al studied in single crystals

Pospisil, J.; Opletal, P.*; Vali$v{s}$ka, M.*; Tokunaga, Yo; Stunault, A.*; Haga, Yoshinori; Tateiwa, Naoyuki; Gillon, B.*; Honda, Fuminori*; Yamamura, Tomoo*; et al.

Journal of the Physical Society of Japan, 85(3), p.034710_1 - 034710_10, 2016/03

 Times Cited Count:9 Percentile:56.51(Physics, Multidisciplinary)

Journal Articles

Enhancement of the cyclotron effective mass in U$$_{0.03}$$Th$$_{0.97}$$Ru$$_2$$Si$$_2$$

Haga, Yoshinori; Matsumoto, Yuji*; Tateiwa, Naoyuki; Yamamoto, Etsuji; Kimura, Noriaki*; Yamamura, Tomoo*; Fisk, Z.

Journal of Physics; Conference Series, 592(1), p.012036_1 - 012036_5, 2015/03

 Times Cited Count:2 Percentile:61.58

Journal Articles

Large reversible magnetocaloric effect in ferromagnetic semiconductor EuS

Li, D. X.*; Yamamura, Tomoo*; Nimori, Shigeki*; Homma, Yoshiya*; Honda, Fuminori*; Haga, Yoshinori; Aoki, Dai*

Solid State Communications, 193, p.6 - 10, 2014/09

 Times Cited Count:23 Percentile:67.06(Physics, Condensed Matter)

Journal Articles

Competition between magnetic ordering and random spin freezing in Dy$$_2$$PtS$$_3$$

Li, D.*; Yamamura, Tomoo*; Homma, Yoshiya*; Yubuta, Kunio*; Shikama, Tatsuo*; Aoki, Dai*; Nimori, Shigeki*; Haga, Yoshinori

Journal of the Korean Physical Society, 62(12), p.2233 - 2238, 2013/06

 Times Cited Count:3 Percentile:27.73(Physics, Multidisciplinary)

Journal Articles

Actinide-handling experience for training and education of future expert under J-ACTINET

Osaka, Masahiko; Konashi, Kenji*; Hayashi, Hirokazu; Li, D.*; Homma, Yoshiya*; Yamamura, Tomoo*; Sato, Isamu; Miwa, Shuhei; Sekimoto, Shun*; Kubota, Takumi*; et al.

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields.

Journal Articles

Evidence for spin-glass state in nonmagnetic atom disorder compound Pr$$_2$$AgIn$$_3$$

Li, D. X.*; Yamamura, Tomoo*; Yubuta, Kunio*; Nimori, Shigeki*; Haga, Yoshinori; Shikama, Tatsuo*

Journal of Physics; Conference Series, 320, p.012041_1 - 012041_6, 2011/09

 Times Cited Count:9 Percentile:89.36

JAEA Reports

Utilization of actinide as cell active materials; Effective utilization of uranium as battery active material, JAERI's nuclear research promotion program, H10-034-2 (Contract research)

Yamana, Hajimu*; Moriyama, Hirotake*; Asano, Hideki*; Shiokawa, Yoshinobu*; Yamamura, Tomoo*; Hasegawa, Kazuki*; Kimura, Akihiro*; Umekita, Satoshi*

JAERI-Tech 2002-018, 33 Pages, 2002/03


no abstracts in English

JAEA Reports

Utilization of actinide as cell active materials, JAERI's nuclear research promotion program, H10-034-1 (Contract research)

Shiokawa, Yoshinobu*; Yamamura, Tomoo*; Watanabe, Nobutaka*; Umekita, Satoshi*

JAERI-Tech 2002-017, 50 Pages, 2002/03


no abstracts in English

Oral presentation

Specific heat of uranium chalcogenides

Yamamoto, Etsuji; Haga, Yoshinori; Tateiwa, Naoyuki; Ikeda, Shugo*; Sakai, Hironori; Yamamura, Tomoo*; Fisk, Z.

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)