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Journal Articles

Crystal-like atomic arrangement and optical properties of 25La$$_{2}$$O$$_{3}$$-75MoO$$_{3}$$ binary glasses composed of isolated MoO$$_{4}$$$$^{2-}$$

Masuno, Atsunobu*; Munakata, Sae*; Okamoto, Yoshihiro; Yaji, Toyonari*; Kosugi, Yoshihisa*; Shimakawa, Yuichi*

Inorganic Chemistry, 63(12), p.5701 - 5708, 2024/03

 Times Cited Count:0 Percentile:0.05(Chemistry, Inorganic & Nuclear)

Transparent and brown La$$_{2}$$O$$_{3}$$-MoO$$_{3}$$ binary glasses were prepared in bulk form using a levitation technique. The glass-forming range was limited, with the primary composition being approximately 25 mol% La$$_{2}$$O$$_{3}$$. This glass exhibited a clear crystallization at 546 $$^{circ}$$C, while determining its glass transition temperature was difficult. Notably, despite its amorphous nature, the glass possessed a density and packing density comparable to those of crystalline La$$_{2}$$Mo$$_{3}$$O$$_{12}$$. X-ray absorption fine structure and Raman scattering analyses revealed that the glass structure closely resembles La$$_{2}$$Mo$$_{3}$$O$$_{12}$$ due to the presence of isolated MoO$$_{4}$$$$^{2-}$$ units, whereas disordered atomic arrangement around La atoms was confirmed. The glass demonstrated transparency ranging from 378 to 5500 nm, and the refractive index at 1.0 $$mu$$m was estimated to be 2.0. The optical bandgap energy was 3.46 eV, which was slightly smaller than that of La$$_{2}$$Mo$$_{3}$$O$$_{12}$$. Additionally, the glass displayed a transparent region ranging from 6.5 to 8.0 $$mu$$m. This occurrence results from the decreased diversity of MoO$$_{n}$$ units and connectivity of Mo-O-Mo, which resulted in the reduced overlap of multiphonon absorption. This glass formation, with its departure from conventional glass-forming rules, resulted in distinctive glasses with crystal-like atomic arrangements.

Journal Articles

Giant multiple caloric effects in charge transition ferrimagnet

Kosugi, Yoshihisa*; Goto, Matato*; Tan, Z.*; Kan, Daisuke*; Isobe, Masahiko*; Yoshii, Kenji; Mizumaki, Masaichiro*; Fujita, Asaya*; Takagi, Hidenori*; Shimakawa, Yuichi*

Scientific Reports (Internet), 11(1), p.12682_1 - 12682_8, 2021/06

 Times Cited Count:5 Percentile:43.44(Multidisciplinary Sciences)

Caloric effects of solids provide more efficient and environment-friendly innovative refrigeration systems compared to the widely-used conventional vapor compressive cooling systems. Exploring novel caloric materials is challenging but critically important in developing future technologies. Here we discovered that the quadruple perovskite structure ferrimagnet BiCu$$_{3}$$Cr$$_{4}$$O$$_{12}$$ shows a large multicaloric effect at the first-order charge transition occurred around 190 K. Large latent heat and the corresponding isothermal entropy changes 28.2 J K$$^{-1}$$ kg$$^{-1}$$ can be fully utilized by applying both magnetic fields (magnetocaloric effect) and pressure (barocaloric effect). Adiabatic temperature changes reach 3.9 K for the 50 kOe magnetic field and 4.8 K for the 4.9 kbar pressure, and thus highly efficient thermal controls are achieved by multiple ways.

Journal Articles

Emergence of nearly flat bands through a kagome lattice embedded in an epitaxial two-dimensional Ge layer with a bitriangular structure

Fleurence, A.*; Lee, C.-C.*; Friedlein, R.*; Fukaya, Yuki; Yoshimoto, Shinya*; Mukai, Kozo*; Yamane, Hiroyuki*; Kosugi, Nobuhiro*; Yoshinobu, Jun*; Ozaki, Taisuke*; et al.

Physical Review B, 102(20), p.201102_1 - 201102_6, 2020/11

 Times Cited Count:2 Percentile:12.54(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

C-face interface defects in 4H-SiC MOSFETs studied by electrically detected magnetic resonance

Umeda, Takahide*; Okamoto, Mitsuo*; Arai, Ryo*; Sato, Yoshihiro*; Kosugi, Ryoji*; Harada, Shinsuke*; Okumura, Hajime*; Makino, Takahiro; Oshima, Takeshi

Materials Science Forum, 778-780, p.414 - 417, 2014/02

 Times Cited Count:2 Percentile:72.57(Crystallography)

Interface defects of Metal-Oxide-Semiconductors (MOSFETs) fabricated on Carbone (C) face 4H-SiC were investigated by Electrically Detected Magnet Resistance (EDMR). Gate oxide of the MOSFETs was formed by either wet-oxidation and H$$_{2}$$ annealing or dry-oxidation. The values of channel mobility for MOSFETS with wet gate oxide and dry gate oxide are less than 1 and 90 cm$$^{2}$$/Vs, respectively. By EDMR measurement under low temperature (less than 20 K), EDMR signals related to C were detected. The peak height of the signals increased with increasing $$gamma$$-ray doses, and the channel mobility decreased. From this result, it is assumed that hydrogen atoms passivating C dangling bonds are released by $$gamma$$-rays and the channel mobility decreases with increasing the C related defects.

Journal Articles

Elucidations of the catalytic cycle of NADH-cytochrome $$b$$$$_{5}$$ reductase by X-ray crystallography; New insights into regulation of efficient electron transfer

Yamada, Mitsugu*; Tamada, Taro; Takeda, Kazuki*; Matsumoto, Fumiko*; Ono, Hiraku*; Kosugi, Masayuki*; Takaba, Kiyofumi*; Shoyama, Yoshinari*; Kimura, Shigenobu*; Kuroki, Ryota; et al.

Journal of Molecular Biology, 425(22), p.4295 - 4306, 2013/11

 Times Cited Count:21 Percentile:50.49(Biochemistry & Molecular Biology)

NADH-Cytochrome $$b$$$$_{5}$$ reductase (b5R), a flavoprotein consisting of NADH and flavin adenine dinucleotide (FAD) binding domains, catalyzes electron transfer from the two-electron carrier NADH to the one-electron carrier cytochrome $$b$$$$_{5}$$ (Cb5). The crystal structures of both the fully reduced form and the oxidized form of porcine liver b5R were determined. In the reduced b5R structure determined at 1.68${AA}$ resolution, the relative configuration of the two domains was slightly shifted in comparison with that of the oxidized form. This shift resulted in an increase in the solvent-accessible surface area of FAD and created a new hydrogen-bonding interaction between the N5 atom of the isoalloxazine ring of FAD and the hydroxyl oxygen atom of Thr66, which is considered to be a key residue in the release of a proton from the N5 atom. The isoalloxazine ring of FAD in the reduced form is flat as in the oxidized form and stacked together with the nicotinamide ring of NAD$$^{+}$$. Determination of the oxidized b5R structure, including the hydrogen atoms, determined at 0.78${AA}$ resolution revealed the details of a hydrogen-bonding network from the N5 atom of FAD to His49 via Thr66. Both of the reduced and oxidized b5R structures explain how backflow in this catalytic cycle is prevented and the transfer of electrons to one-electron acceptors such as Cb5 is accelerated. Furthermore, crystallographic analysis by the cryo-trapping method suggests that re-oxidation follows a two-step mechanism. These results provide structural insights into the catalytic cycle of b5R.

Journal Articles

Change in magnetic properties induced by swift heavy ion irradiation in CeO$$_{2}$$

Shimizu, Hirotaka*; Kosugi, Shinya*; Tahara, Yuki*; Yasunaga, Kazufumi*; Kaneta, Yasunori*; Ishikawa, Norito; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 286, p.291 - 294, 2012/09

 Times Cited Count:27 Percentile:87.4(Instruments & Instrumentation)

We have studied the magnetic properties of pure CeO$$_{2}$$ irradiated with swift heavy ions. Experiment a results showed that the ferromagnetism was induced even at room temperature by 200 MeV Xe ion irradiation. The value of saturation magnetization, Ms, systematically changes as a function of ion-fluence. The X-ray diffraction (XRD) spectra show that the lattice constant of CeO$$_{2}$$ increases with increasing ion-fluence. This result and our previous XPS result show that the ion-irradiation produced oxygen vacancies. The present study implies that the ferromagnetic behavior of the ion-irradiated CeO$$_{2}$$ is attributed to the magnetic moments of localized 4f electrons on Ce$$^{3+}$$ atoms, which are related to oxygen vacancies.

Journal Articles

Electrically Detected Magnetic Resonance (EDMR) studies of SiC-SiO$$_{2}$$ interfaces

Umeda, Takahide*; Kosugi, Ryoji*; Fukuda, Kenji*; Morishita, Norio*; Oshima, Takeshi; Ezaki, Kana*; Isoya, Junichi*

Materials Science Forum, 717-720, p.427 - 432, 2012/05

 Times Cited Count:7 Percentile:95.04(Materials Science, Multidisciplinary)

Metal-Oxide (SiO$$_{2}$$)-Semiconductor (MOS) structures fabricated on Silicon Carbide (SiC) were studied using Electrically Detected Magnetic Resonance technique (EDMR). The residual Carbons are expected to be near the interface between SiC and SiC-SiO$$_{2}$$SiO$$_{2}$$, which is different from Si-SiO$$_{2}$$ interface. By the EDMR measurements at 50K, a defect center related to C dangling bonds which is called P$$_{H1}$$ center and also a center related to C dangling bonds terminated by hydrogens or nitrogens (Ns) which is called P$$_{H1}$$ were observed. In addition, a center related to N donor which is called Nh exist near the interface from N-treatment samples. This suggests that carrier concentration increases near the interface due to the introduction of donors, and as a result, the channel conductance increases.

Journal Articles

Mass production results of superconducting cables for CS and EF coils of JT-60SA

Sugimoto, Masahiro*; Kosugi, Keizo*; Katayama, Kota*; Ii, Hideki*; Takagi, Akira*; Endo, Sakaru*; Shimizu, Hitoshi*; Tsubouchi, Hirokazu*; Kizu, Kaname; Yoshida, Kiyoshi

Proceedings of 24th International Cryogenic Engineering Conference (ICEC 24) and International Cryogenic Materials Conference 2012 (ICMC 2012) (CD-ROM), p.799 - 802, 2012/05

We have successfully manufactured all superconducting cables for CS and EF coils of JT-60SA. The low temperature performance of superconducting wires satisfied the specifications under sufficiently low deviations and high production yields. Ni-plated strands of EF cables having the larger sliding friction between strands than that of Cr-plated strands of CS cable caused difficulties on the cabling without any defects. Consequently, the newly developed cabling techniques with the original inspection apparatus significantly enhanced the manufacturability and were effective for guarantee of the quality.

Journal Articles

Hardness modification of aluminum-alloys by means of energetic ion irradiation and subsequent thermal aging

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Nuclear Instruments and Methods in Physics Research B, 272, p.49 - 52, 2012/02

 Times Cited Count:9 Percentile:56.74(Instruments & Instrumentation)

Journal Articles

X-ray study of radiation damage in UO$$_{2}$$ irradiated with high-energy heavy ions

Ishikawa, Norito; Sonoda, Takeshi*; Okamoto, Yoshihiro; Sawabe, Takashi*; Takegahara, Keisuke; Kosugi, Shinya*; Iwase, Akihiro*

Journal of Nuclear Materials, 419(1-3), p.392 - 396, 2011/12

 Times Cited Count:10 Percentile:60.68(Materials Science, Multidisciplinary)

In order to characterize the radiation damage due to ion-track formation in UO$$_{2}$$, polycrystalline samples have been irradiated with 210-MeV Xe ions, and measured with XRD (X-ray diffraction) technique using Cu X-ray. We have also tried EXAFS (extended X-ray absorption fine structure) measurement using X-ray near U L$$_{3}$$-edge. The results show that XRD technique detects damage at relatively low fluence of 10$$^{16}$$ ions/m$$^{2}$$ and higher, while the irradiation-induced change of EXAFS spectra is not observed even at highest fluence of 10$$^{19}$$ ions/m$$^{2}$$. The damage detection may be critically influenced by the depth profile of X-ray penetration.

Journal Articles

Behavior of nitrogen atoms in SiC-SiO$$_{2}$$ interfaces studied by electrically detected magnetic resonance

Umeda, Takahide*; Ezaki, Kana*; Kosugi, Ryoji*; Fukuda, Kenji*; Oshima, Takeshi; Morishita, Norio*; Isoya, Junichi*

Applied Physics Letters, 99(14), p.142105_1 - 142105_3, 2011/10

 Times Cited Count:50 Percentile:85.77(Physics, Applied)

Journal Articles

Study on effects of swift heavy ion irradiation on the crystal structure in CeO$$_{2}$$ doped with Gd$$_{2}$$O$$_{3}$$

Tahara, Yuki*; Zhu, B.-L.*; Kosugi, Shinya*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 269(9), p.886 - 889, 2011/05

 Times Cited Count:16 Percentile:75.64(Instruments & Instrumentation)

CeO$$_{2}$$ pellets doped with Gd$$_{2}$$O$$_{3}$$ were irradiated with 200-MeV Xe ions, and the effects of Gd$$_{2}$$O$$_{3}$$-doping and irradiation on the lattice structure were measured using XRD and EXAFS. The lattice constant decreases with increasing Gd$$_{2}$$O$$_{3}$$-doping and the local structure near the Gd atoms is more disordered with increasing amounts of Gd$$_{2}$$O$$_{3}$$-dopant. The irradiation induces an expansion of the lattice and disordering of the atomic arrangement around Gd atoms. The effect of high-energy ion irradiation becomes more pronounced with increasing amounts of Gd$$_{2}$$O$$_{3}$$-dopant.

Journal Articles

Effect of high temperature annealing on ferromagnetism induced by energetic ion irradiation in FeRh alloy

Kosugi, Shinya*; Fujita, Naoki*; Matsui, Toshiyuki*; Hori, Fuminobu*; Saito, Yuichi; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 269(9), p.869 - 872, 2011/05

 Times Cited Count:10 Percentile:60.68(Instruments & Instrumentation)

Effects of thermal annealing on ion-irradiation induced ferromagnetism of FeRh bulk alloy and the related structural change were investigated by means of superconducting quantum interference device (SQUID) and extended X-ray absorption fine structure (EXAFS), respectively. Depending on the annealing temperature from 100 to 500 $$^{circ}$$C, the magnetization induced by 10 MeV iodine ion irradiation and the lattice structure of the alloy were remarkably changed. After 500 $$^{circ}$$C annealing, the magnetization and the lattice ordering of the alloy become similar to the states before the irradiation. The experimental result indicates that the thermal relaxation of irradiation-induced atomic disordering dominates the magnetic state of ion-irradiated FeRh alloy.

Journal Articles

Study on ion-irradiation-induced ferromagnetism in FeRh intermetallic compound by means of magnetic Compton scattering

Kosugi, Shinya*; Matsui, Toshiyuki*; Ishikawa, Norito; Ito, Masayoshi*; Sakurai, Yoshiharu*; Aiko, Kazuma*; Shimizu, Hirotaka*; Tahara, Yuki*; Hori, Fuminobu*; Iwase, Akihiro*

Journal of Applied Physics, 109(7), p.07B737_1 - 07B737_3, 2011/04

 Times Cited Count:7 Percentile:31.11(Physics, Applied)

The magnetic Compton profiles of FeRh intermetallic compound were measured to study the ferromagnetism induced by 200 MeV Xe ion irradiation. The magnetic effect at 50 K increases with increasing the ion-fluence. The analysis of the experimental result revealed that the values of spin moment induced by the irradiation were close to the values of magnetization obtained by a superconducting quantum interference device magnetometer, suggesting that the ion irradiation mainly induces the spin magnetic moment.

Journal Articles

Determination of threshold energies for displacements of Fe and Rh atoms in Fe-50 at.%Rh intermetallic compound by using energetic electron irradiation at low temperatures

Kosugi, Shinya*; Ishikawa, Norito; Saito, Yuichi; Hori, Fuminobu*; Iwase, Akihiro*

Journal of Nuclear Materials, 411(1-3), p.171 - 173, 2011/04

 Times Cited Count:3 Percentile:25.9(Materials Science, Multidisciplinary)

Changes in electrical resistivity induced by irradiation with energetic electrons were measured for Fe-50 at.%Rh alloy as a function of electron energy in the range from 0.5 to 2.0 MeV. The irradiation was carried out below 20 K and the resistivity was measured at 10 K. The electron energy dependence of the resistivity change rate was analysed by using a simple displacement theory, and the average threshold energies for atomic displacements, $$E$$$$_{d}$$, were determined as 30 eV for Fe and 45 eV for Rh.

Journal Articles

Hardening of Al-Cu-Mg alloy by energetic ion irradiation

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Journal of Nuclear Materials, 408(2), p.201 - 204, 2011/01

 Times Cited Count:13 Percentile:69.55(Materials Science, Multidisciplinary)

Journal Articles

Micrometer-sized magnetic patterning of FeRh films using an energetic ion microbeam

Fujita, Naoki*; Matsui, Toshiyuki*; Kosugi, Shinya*; Sato, Takahiro; Saito, Yuichi; Takano, Katsuyoshi; Koka, Masashi; Kamiya, Tomihiro; Seki, Shu*; Iwase, Akihiro*

Japanese Journal of Applied Physics, 49(6), p.060211_1 - 060211_3, 2010/06

 Times Cited Count:12 Percentile:45.72(Physics, Applied)

Journal Articles

Effects of energetic heavy ion irradiation on the structure and magnetic properties of FeRh thin films

Fujita, Naoki*; Kosugi, Shinya*; Zushi, Yoshihiro*; Matsui, Toshiyuki*; Saito, Yuichi; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 267(6), p.921 - 924, 2009/04

 Times Cited Count:9 Percentile:53.42(Instruments & Instrumentation)

Journal Articles

Economical evaluation on Gas Turbine High Temperature Reactor 300 (GTHTR300)

Takei, Masanobu*; Kosugiyama, Shinichi*; Mori, Tomoaki; Katanishi, Shoji; Kunitomi, Kazuhiko

Nihon Genshiryoku Gakkai Wabun Rombunshi, 5(2), p.109 - 117, 2006/06

no abstracts in English

Journal Articles

Research and development for gas turbine system in GTHTR300

Kunitomi, Kazuhiko; Katanishi, Shoji; Takada, Shoji; Takizuka, Takakazu; Yan, X.; Kosugiyama, Shinichi

JSME International Journal, Series B, 47(2), p.261 - 267, 2004/05

The GTHTR300 aiming at electric generation with its thermal efficiency of 46 % is a safe and economically competitive HTGR in 2010s. A helium gas turbine system connected with the reactor is designed based on existing technologies developed for fossil gas turbine systems. However, there are some uncertainties in performance of a helium gas compressor, electric magnetic bearings and control system. In order to confirm these technical uncertainties, a 1/3 scale model of the compressor and 1/3 scale magnetic bearings will be manufactured and tested in the simulated condition of the GTHTR300. This paper describes R&D plans focusing on the 1/3 scale compressor model test as well as unique design features of the GTHTR300.

46 (Records 1-20 displayed on this page)