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Journal Articles

Ultrafast carrier dynamics and light-induced functionalizations of topological insulators

Sumida, Kazuki; Ishida, Yukiaki*; Kimura, Akio*

Nippon Butsuri Gakkai-Shi, 75(12), p.756 - 760, 2020/12

Journal Articles

Spin-polarized Weyl cones and giant anomalous Nernst effect in ferromagnetic Heusler films

Sumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taiichi*; et al.

Communications Materials (Internet), 1, p.89_1 - 89_9, 2020/11

Journal Articles

Evaluation of the characteristics of metal nitrate aqueous solutions by microwave heating and the morphologies of synthesized metal oxide powders

Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Fukasawa, Tomonori*; Fukui, Kunihiro*

Funtai Kogakkai-Shi, 57(9), p.485 - 494, 2020/09

In the spent fuel reprocessing process, a mixed solution of uranyl nitrate and plutonium nitrate is converted into mixed oxide powder by the microwave heating. To evaluate the applicability to the industrial-scale and acquire the characteristics data of the microwave heating denitration of various metal nitrate aqueous solutions based on the knowledge studied in the development of laboratory-scale basic experiments, the microwave heating characteristics and metal oxide powder properties were investigated using cerium nitrate, cobalt nitrate and copper nitrate aqueous solutions. The progress rate of the denitration reaction was depended on the position, and the denitration reaction proceeded faster at the periphery than at the center. The morphologies of the synthesized products were porous and hard dry solid with cerium nitrate aqueous solution, foamed dry solid with cobalt nitrate aqueous solution, and powdery particles with copper nitrate aqueous solution. The denitration ratio and average particle size of the synthesized products increased in the order of the cerium nitrate aqueous solution, the cobalt nitrate aqueous solution, and the copper nitrate aqueous solution. The numerical simulations revealed that the periphery of the bottom surface of the metal nitrate aqueous solution was heated by microwaves. This results consistent with the experimental results in which the denitration reaction started from the periphery of the metal nitrate aqueous solution.

Journal Articles

Unveiling spin-dependent unoccupied electronic states of Co$$_{2}$$MnGe (Ga) film via Ge (Ga) $$L_{2,3}$$ absorption spectroscopy

Yoshikawa, Tomoki*; Antonov, V. N.*; Kono, Takashi*; Kakoki, Masaaki*; Sumida, Kazuki; Miyamoto, Koji*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; Sakuraba, Yuya*; et al.

Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Journal Articles

Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi$$_{2}$$Te$$_{4}$$

Shikin, A. M.*; Estyunin, D. A.*; Klimovskikh, I. I.*; Filnov, S. O.*; Kumar, S.*; Schwier, E. F.*; Miyamoto, Koji*; Okuda, Taiichi*; Kimura, Akio*; Kuroda, Kenta*; et al.

Scientific Reports (Internet), 10, p.13226_1 - 13226_13, 2020/08

 Times Cited Count:0 Percentile:100(Multidisciplinary Sciences)

Journal Articles

Manipulation of saturation magnetization and perpendicular magnetic anisotropy in epitaxial Co$$_{x}$$Mn$$_{4-x}$$N films with ferrimagnetic compensation

Ito, Keita*; Yasutomi, Yoko*; Zhu, S.*; Nurmamat, M.*; Tahara, Masaki*; Toko, Kaoru*; Akiyama, Ryota*; Takeda, Yukiharu; Saito, Yuji; Oguchi, Tamio*; et al.

Physical Review B, 101(10), p.104401_1 - 104401_8, 2020/03

 Times Cited Count:1 Percentile:31.73(Materials Science, Multidisciplinary)

Journal Articles

Thermal behavior of perlite concrete used in a sodium-cooled fast reactor; Multistep reaction kinetics and melting for safety assessment

Koga, Nobuyoshi*; Kikuchi, Shin

Journal of Thermal Analysis and Calorimetry, 138(2), p.983 - 996, 2019/10

 Times Cited Count:3 Percentile:58.41(Thermodynamics)

Detailed understanding of the thermal decomposition of the structural concretes used in the sodium-cooled fast reactor is essentially important to simulate the possible phenomena that occurs under postulated severe accident of the nuclear power plant. In this study, the thermal decomposition behaviour of a perlite concrete and two siliceous concretes used in a sodium-cooled fast reactor was comparatively investigated.

Journal Articles

Element-specific density of states of Co$$_{2}$$MnGe revealed by resonant photoelectron spectroscopy

Kono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki*; Miyamoto, Koji*; Muro, Takayuki*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; et al.

Physical Review B, 100(16), p.165120_1 - 165120_6, 2019/10

 Times Cited Count:1 Percentile:76.22(Materials Science, Multidisciplinary)

Journal Articles

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators Sb$$_{2-x}$$V$$_{x}$$Te$$_{3}$$

Sumida, Kazuki*; Kakoki, Masaaki*; Reimann, J.*; Nurmamat, M.*; Goto, Shinichi*; Takeda, Yukiharu; Saito, Yuji; Kokh, K. A.*; Tereshchenko, O. E.*; G$"u$dde, J.*; et al.

New Journal of Physics (Internet), 21(9), p.093006_1 - 093006_8, 2019/09

 Times Cited Count:1 Percentile:65.14(Physics, Multidisciplinary)

Journal Articles

Technological development of the particle size adjustment of dry recovered powder

Segawa, Tomoomi; Yamamoto, Kazuya; Makino, Takayoshi; Iso, Hidetoshi; Kawaguchi, Koichi; Ishii, Katsunori; Sato, Hisato; Fukasawa, Tomonori*; Fukui, Kunihiro*

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.738 - 745, 2019/09

In the MOX fuel fabrication process, the dry grinding technology of mixed oxide pellets have been developed for the effective use of nuclear fuel materials. To develop a technology to control the particle size of dry recovered powder, the performance of the buhrstone mill and the collision plate type jet mill were studied using a simulated powder of particle size distribution about 500 $$mu$$m. We found that the particle size can be controlled at the range of about 250 $$mu$$m or less by both by adjusting the clearance between the grinding wheels of the buhrstone mill, and the clearance and elevation angle of the clarification zone of the the collision plate type jet mill. And furthermore, the collision plate type jet mill is considered to be suitable for particle size control because the operating parameters of the classifier can be finely adjusted.

Journal Articles

Comparative study on the thermal behavior of structural concretes of sodium-cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*; Yamazaki, Atsushi*

Journal of Thermal Analysis and Calorimetry, 137(4), p.1211 - 1224, 2019/08

 Times Cited Count:2 Percentile:58.41(Thermodynamics)

In this study, two siliceous concretes with similar specification as structural concretes of SFR were selected for the comparative study of the thermal behavior. The thermal behavior of the structural concretes was investigated in a temperature range from room temperature to 1900 K using TG-differential thermal analysis (DTA) and other supplementary techniques. The softening and melting of the concretes initiated in the thermal decomposition product of the cement portion in the temperature range 1400-1600 K. Because the compositional difference between the cement portion of two different siliceous concretes was characterized by different Ca(OH)$$_{2}$$/CaCO$$_{3}$$ ratios, the melting temperature ranges of those thermal decomposition products are not so significantly different. On the other hand, the melting of the aggregate is directly influenced by the initial composition of SiO$$_{2}$$ compounds.

Journal Articles

Negative Te spin polarization responsible for ferromagnetic order in the doped topological insulator V$$_{0.04}$$(Sb$$_{1-x}$$Bi$$_{x}$$)$$_{1.96}$$Te$$_{3}$$

Ye, M.*; Xu, T.*; Li, G.*; Qiao, S.*; Takeda, Yukiharu; Saito, Yuji; Zhu, S.-Y.*; Nurmamat, M.*; Sumida, Kazuki*; Ishida, Yukiaki*; et al.

Physical Review B, 99(14), p.144413_1 - 144413_7, 2019/04

 Times Cited Count:5 Percentile:43.12(Materials Science, Multidisciplinary)

Journal Articles

Dirac gap opening and Dirac-fermion-mediated magnetic coupling in antiferromagnetic Gd-doped topological insulators and their manipulation by synchrotron radiation

Shikin, A. M.*; Estyunin, D. A.*; Surnin, Yu. I.*; Koroleva, A. V.*; Shevchenko, E. V.*; Kokh, K. A.*; Tereshchenko, O. E.*; Kumar, S.*; Schwier, E. F.*; Shimada, Kenya*; et al.

Scientific Reports (Internet), 9(1), p.4813_1 - 4813_17, 2019/03

 Times Cited Count:6 Percentile:26.52(Multidisciplinary Sciences)

Journal Articles

Development of synthesis and morphology control method of metallic oxide particles using microwave heating

Segawa, Tomoomi

Funtai Kogakkai-Shi, 55(10), P. 547, 2018/10

no abstracts in English

Journal Articles

Preferred site occupation of 3$$d$$ atoms in Ni$$_{x}$$Fe$$_{4-x}$$N (${it x}$ = 1 and 3) films revealed by X-ray absorption spectroscopy and magnetic circular dichroism

Takata, Fumiya*; Ito, Keita*; Takeda, Yukiharu; Saito, Yuji; Takanashi, Koki*; Kimura, Akio*; Suemasu, Takashi*

Physical Review Materials (Internet), 2(2), p.024407_1 - 024407_5, 2018/02

 Times Cited Count:7 Percentile:43.2(Materials Science, Multidisciplinary)

Journal Articles

Thermal behavior of sodium hydroxide-structural concrete composition of sodium-cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*

Journal of Thermal Analysis and Calorimetry, 131(1), p.301 - 308, 2018/01

 Times Cited Count:2 Percentile:76.27(Thermodynamics)

Under postulated accidental condition of sodium-cooled fast reactor (SFR), liquid sodium spill into the floor may lead to fail the steel liner resulting in sodium-concrete reaction (SCR). In this study, the sodium hydroxide (NaOH)-silica (SiO$$_{2}$$) reaction as one of possible secondary stage reactions was investigated for safety assessment of SFR. Thermal behavior of NaOH-SiO$$_{2}$$ reaction such as reaction onset was determined using a differential scanning calorimetry (DSC). As a result of DSC measurement, it was revealed that NaOH-SiO$$_{2}$$ reaction occurs as rapid reaction right after NaOH melting at 583 K. Therefore, it was expected that NaOH-SiO$$_{2}$$ reaction is dominant in the time frame of secondary stage of SCR if significant amount of NaOH has been generated during the initial stage reaction.

Journal Articles

Pressure studies on the antiferromagnetic Kondo semiconductor Ce(Ru$$_{1-x}$$Rh$$_x$$)$$_2$$Al$$_{10}$$ (x = 0,0.1)

Tanida, Hiroshi*; Kitagawa, Kentaro*; Tateiwa, Naoyuki; Sera, Masafumi*; Nishioka, Takashi*

Physical Review B, 96(23), p.235131_1 - 235131_7, 2017/12

 Times Cited Count:1 Percentile:89.48(Materials Science, Multidisciplinary)

We have done high pressure experiments on Ce(Ru$$_{1-x}$$Rh$$_x$$)$$_2$$Al$$_{10}$$ (x = 0 and 0.1) to study pressure-induced phase transitions from the antiferromagnetic to paramagnetic state at $$P_c$$. Experimental data of the electrical resistivity suggest that the $$c$$-$$f$$ hybridization gap could be not necessary to form the unusual AFM order. The pressure effects on the magnetic susceptibility is also studied. We discuss a difference in the pressure response of the magnetic susceptibility based the electronic state between x = 0 and 0.1.

Journal Articles

Validation of measured microwave absorption and temperature change for development of a single-mode-type microwave heating thermogravimetry apparatus

Karisma, A. D.*; Hamaba, Taishu*; Fukasawa, Tomonori*; Huang, A.-N.*; Segawa, Tomoomi; Fukui, Kunihiro*

Review of Scientific Instruments, 88(2), p.024101_1 - 024101_8, 2017/02

 Times Cited Count:1 Percentile:89.15(Instruments & Instrumentation)

Microwave heating direct denitration method is used in the nuclear fuel reprocessing process. In order to develop a single-mode-type microwave heating thermogravimetry apparatus which can perform detailed analysis of the characteristics of microwave heating, the temperature dependence of microwave absorption is verified. The temperature distribution, microwave absorption efficiency, and dielectric properties of a CuO pellet that was heated by the microwave irradiation were investigated. The temperature distribution in the CuO pellet due to one-way travel of the microwave in the apparatus was accurately reproduced by a three-dimensional numerical simulation of the electromagnetic field. The numerically determined temperature dependency of the CuO absorption efficiency was found to be in very good agreement with published data.

Journal Articles

Influence of the heating method on the particle characteristics of copper oxide powders synthesized from copper nitrate aqueous solutions

Segawa, Tomoomi; Fukasawa, Tomonori*; Huang, A.-N.*; Yamada, Yoshikazu; Suzuki, Masahiro; Fukui, Kunihiro*

Chemical Engineering Science, 153, p.108 - 116, 2016/10

 Times Cited Count:3 Percentile:79.5(Engineering, Chemical)

The influence of the heating method and rate on the morphology of CuO powders synthesized from Cu(NO$$_{3}$$)$$_{2}$$$$cdot$$3H$$_{2}$$O aqueous solutions by denitration was investigated. The median diameter of the obtained powder was found to decrease as the heating rate increased, independent of the heating method. The microwave heating method remarkably reduced the particle size and enhanced the irregularity and disorder of the shape and surface of the particles, which were found to be more widely distributed. In contrast, the microwave hybrid heating method yielded the most spherical particles with the smoothest surface. It was also found that this heating method sharpened the particle size distribution and had higher energy efficiency than the MW method. Numerical simulations also indicated a difference in the energy efficiency between these two methods. The simulations also revealed that the hybrid method could heat the whole reactor more uniformly with a lower microwave output.

Journal Articles

Age and speciation of iodine in groundwater and mudstones of the Horonobe area, Hokkaido, Japan; Implications for the origin and migration of iodine during basin evolution

Togo, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Suzuki, Yohei*; Terada, Yasuko*; Muramatsu, Yasuyuki*; Ito, Kazumasa*; Iwatsuki, Teruki

Geochimica et Cosmochimica Acta, 191, p.165 - 186, 2016/10

 Times Cited Count:13 Percentile:31.03(Geochemistry & Geophysics)

Iodine distribution, speciation, and isotope ratio ($$^{129}$$I/$$^{127}$$I) in both rock and groundwater phases were determined to investigate long-term migration of iodine in diatomaceous and siliceous shale. It was suggested that I$$^{-}$$ is released to the ground water during the progress of the maturation of organic matter. Dissociated I$$^{-}$$ could move toward the surface because of the upward water flow driven by the compaction during burial diagenetic process. Thus, iodine rich brine is created by integration of iodine released from underlying formations. Because of low affinity of I$$^{-}$$ to solid phase, released I$$^{-}$$ remains in solution phase, and the concentration of the iodine in the solution has been possibly increasing during sedimentation history.

171 (Records 1-20 displayed on this page)