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Microstructural features and ductile-brittle transition behavior in hot-rolled lean duplex stainless steels

高橋 治*; 渋井 洋平*; 徐 平光; Harjo, S.; 鈴木 徹也*; 友田 陽*

Quantum Beam Science (Internet), 4(1), p.16_1 - 16_15, 2020/03

The characteristics of texture and microstructure of lean duplex stainless steels with low Ni content produced through hot rolling followed by annealing were investigated locally with electron backscatter diffraction and globally with neutron diffraction. Then, the ductile-brittle transition (DBT) behavior was studied by Charpy impact test. It is found that the DBT temperature (DBTT) is strongly affected by the direction of crack propagation, depending on crystallographic texture and microstructural morphology; the DBTT becomes extremely low in the case of fracture accompanying delamination. A high Ni duplex stainless steel examined for comparison, shows a lower DBTT compared with the lean steel in the same crack propagating direction. The obtained results were also discussed through comparing with those of cast duplex stainless steels reported previously (Takahashi et al., Tetsu-to-Hagane, 100(2014), 1150).


Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

近藤 恭弘; 平野 耕一郎; 伊藤 崇; 菊澤 信宏; 北村 遼; 森下 卓俊; 小栗 英知; 大越 清紀; 篠崎 信一; 神藤 勝啓; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

 被引用回数:0 パーセンタイル:100

J-PARC加速器の要素技術試験に必要な3MeV H$$^{-}$$リニアックを高度化した。イオン源にはJ-PARCリニアックと同じものを用い、RFQは、J-PARCリニアックで2014年まで使用した30mA RFQに代わり新たに製作した50mA RFQを設置した。したがって、このシステムはエネルギー3MeV、ビーム電流50mAとなる。このリニアックの本来の目的は、このRFQの試験であるが、J-PARC加速器の運転維持に必要な様々な機器の試験を行うことができる。加速器は既に試運転が終了しており、測定プログラムが開始されつつある。この論文では、この3MeV加速器の現状について報告する。


Vortex rectenna powered by environmental fluctuations

Lustikova, J.*; 塩見 雄毅*; 横井 直人*; 壁谷 典幸*; 木村 憲彰*; 家永 紘一郎*; 金子 真一*; 大熊 哲*; 高橋 三郎*; 齊藤 英治

Nature Communications (Internet), 9, p.4922_1 - 4922_6, 2018/11

 被引用回数:7 パーセンタイル:20.49(Multidisciplinary Sciences)

A rectenna, standing for a rectifying antenna, is an apparatus which generates d.c. electricity from electric fluctuations. It is expected to realize wireless power transmission as well as energy harvesting from environmental radio waves. To realize such rectification, devices that are made up of internal atomic asymmetry such as an asymmetric junction have been necessary so far. Here we report a material that spontaneously generates electricity by rectifying environmental fluctuations without using atomic asymmetry. The sample is a common superconductor without lowered crystalline symmetry, but, just by putting it in an asymmetric magnetic environment, it turns into a rectifier and starts generating electricity. Superconducting vortex strings only annihilate and nucleate at surfaces, and this allows the bulk electrons to feel surface fluctuations in an asymmetric environment: a vortex rectenna. The rectification and generation can be switched on and off with only a slight change in temperature or external magnetic fields.


Application of the transient pulse method to measure clay permeability

加藤 昌治*; 奈良 禎太*; 岡崎 勇樹*; 河野 勝宣*; 佐藤 稔紀; 佐藤 努*; 高橋 学*

Materials Transactions, 59(9), p.1427 - 1432, 2018/09

 被引用回数:0 パーセンタイル:100(Materials Science, Multidisciplinary)



Permeability of granite including macro-fracture naturally filled with fine-grained minerals

奈良 禎太*; 加藤 昌治*; 二里 竜平*; 河野 勝宣*; 佐藤 稔紀; 福田 大祐*; 佐藤 努*; 高橋 学*

Pure and Applied Geophysics, 175(3), p.917 - 927, 2018/03

 被引用回数:3 パーセンタイル:47.96(Geochemistry & Geophysics)




加藤 昌治*; 奈良 禎太*; 岡崎 勇樹*; 河野 勝宣*; 佐藤 稔紀; 佐藤 努*; 高橋 学*

材料, 67(3), p.318 - 323, 2018/03



Control of Ga-oxide interlayer growth and Ga diffusion in SiO$$_{2}$$/GaN stacks for high-quality GaN-based metal-oxide-semiconductor devices with improved gate dielectric reliability

山田 高寛*; 渡邉 健太*; 野崎 幹人*; 山田 永*; 高橋 言緒*; 清水 三聡*; 吉越 章隆; 細井 卓治*; 志村 考功*; 渡部 平司*

Applied Physics Express, 11(1), p.015701_1 - 015701_4, 2018/01

 被引用回数:14 パーセンタイル:10.65(Physics, Applied)

GaN MOSFETは高耐圧・大電流・低損失の次世代スイッチング素子として期待されている。その実現には絶縁膜/GaN界面の特性改善が課題である。本研究ではプラズマCVDによりSiO$$_{2}$$膜を形成したSiO$$_{2}$$/GaN構造の後酸化処理を行い、極薄GaO$$_{x}$$界面層の形成による界面特性向上の効果について検討した。放射光XPS分析から、SiO$$_{2}$$/GaN界面に極薄GaO$$_{x}$$界面層が形成されることを確認した。その界面欠陥密度は、700-800$$^{circ}$$Cでの最適な後酸化処理を施すことによってコンダクタンスピークが確認されず、10$$^{10}$$cm$$^{-2}$$eV$$^{-1}$$台以下の低い値となった。一方、SiO$$_{2}$$/GaO$$_{x}$$/GaN構造の後酸化処理は、SiO$$_{2}$$層中へのGa拡散を誘発し、絶縁性を著しく劣化させた。そこで、後酸化時間を30分間から30秒間とする急速酸化処理を施した。その結果、SiO$$_{2}$$層中へのGa拡散が制限され、優れた界面特性と高い絶縁性を有する高品質なSiO$$_{2}$$/GaO$$_{x}$$/GaN MOS構造が実現できることがわかった。


Estimation of desorption ratios of radio/stable caesium from environmental samples (aerosols and soils) leached with seawater, diluted seawater and ultrapure water

坂口 綾*; 千賀 晴香*; 田中 万也; 鶴田 治雄*; 高橋 嘉夫*

Geochemical Journal, 52(2), p.187 - 199, 2018/00

 被引用回数:4 パーセンタイル:61.1(Geochemistry & Geophysics)



Adsorption of platinum-group metals and molybdenum onto aluminum ferrocyanide in spent fuel solution

大西 貴士; 関岡 健*; 須藤 光雄*; 田中 康介; 小山 真一; 稲葉 優介*; 高橋 秀治*; 針貝 美樹*; 竹下 健二*

Energy Procedia, 131, p.151 - 156, 2017/12

 被引用回数:4 パーセンタイル:1.88

再処理におけるガラス固化プロセスの安定運転のために、白金族元素(Ru, Rh, Pd)およびMoを除去し、安定保管または利用するための分離プロセスの研究開発を実施している。白金族元素とMoを一括回収するための無機吸着剤(フェロシアン化物)が開発されている。本研究では、照射済燃料溶解液を用いた吸着試験を行い、Ru, Rh, Pd, MoおよびAmの吸着特性を評価した。その結果、Ru, Rh, Pd, Moはいずれも吸着が認めら、フェロシアン化物が照射済燃料溶解液中においても一定の吸着性能を示すことがわかった。一方、Amは吸着されないことが確認された。Amが吸着しないことにより、白金族元素とMoの相互分離プロセスにAmが混入せず、アルファ核種を含有する二次廃棄物を大量に発生しないことが確認された。


Generation of megahertz-band spin currents using nonlinear spin pumping

渡辺 真悟*; 廣部 大地*; 塩見 雄毅*; 井口 亮*; 大門 俊介*; 亀田 麻衣*; 高橋 三郎*; 齊藤 英治

Scientific Reports (Internet), 7, p.4576_1 - 4576_6, 2017/07

 被引用回数:4 パーセンタイル:67.78(Multidisciplinary Sciences)

Spin pumping enables the generation of d.c. and gigahertz-band (GHz-band) voltages from an applied microwave via magnetization dynamics when combined with inverse spin Hall effects. However, generating such voltages in the in-between frequency region, or the megahertz (MHz) band, has been difficult since ferromagnetic resonance usually occurs in the GHz band. Here we show that in spite of GHz-band microwaves applied, MHz-band voltages can be generated by spin pumping with use of nonlinear magnetization dynamics in Y$$_3$$Fe$$_5$$O$$_{12}$$. The mechanism is ascribed to the MHz-band oscillation of the amplitude of the magnetization precession, which is projected onto a rectified voltage component via spin pumping. The present finding could be useful for frequency down-conversion thanks to the simple and durable structure, continuous-wave operation, and the tunability of an output frequency with low magnetic fields.


平成28年度技術士試験「原子力・放射線部門」対策講座; 平成27年度技術士一次試験「原子力・放射線部門」; 専門科目の解説

高橋 直樹; 鈴木 惣十; 齋藤 拓人; 上野 隆; 阿部 定好; 山中 淳至; 谷川 聖史; 中村 大司; 佐々木 俊一; 峯 忠治

日本原子力学会ホームページ(インターネット), 20 Pages, 2017/05



Fabrication and magnetic control of Y$$_3$$Fe$$_5$$O$$_{12}$$ cantilevers

Seo, Y.-J.*; 針井 一哉; 高橋 遼*; 中堂 博之; 大柳 洸一*; Qiu, Z.*; 小野 崇人*; 塩見 雄毅*; 齊藤 英治

Applied Physics Letters, 110(13), p.132409_1 - 132409_4, 2017/03

 被引用回数:10 パーセンタイル:31.29(Physics, Applied)




照沼 章弘; 三村 竜二; 長島 久雄; 青柳 義孝; 廣川 勝規*; 打它 正人; 石森 有; 桑原 潤; 岡本 久人; 木村 泰久; et al.

JAEA-Review 2016-008, 98 Pages, 2016/07





加藤 昌治*; 奈良 禎太*; 福田 大祐*; 河野 勝宣*; 佐藤 稔紀; 佐藤 努*; 高橋 学*

材料, 65(7), p.489 - 495, 2016/07



Theory of spin Hall magnetoresistance (SMR) and related phenomena

Chen, Y.-T.*; 高橋 三郎*; 中山 裕康*; Althammer, M.*; Goennenwein, S. T. B.*; 齊藤 英治; Bauer, G. E. W.*

Journal of Physics; Condensed Matter, 28(10), p.103004_1 - 103004_15, 2016/03

 被引用回数:44 パーセンタイル:34.05(Physics, Condensed Matter)



Room-temperature local ferromagnetism and its nanoscale expansion in the ferromagnetic semiconductor Ge$$_{1-x}$$Fe$$_{x}$$

若林 勇希*; 坂本 祥哉*; 竹田 幸治; 石上 啓介*; 高橋 文雄*; 斎藤 祐児; 山上 浩志; 藤森 淳*; 田中 雅明*; 大矢 忍*

Scientific Reports (Internet), 6, p.23295_1 - 23295_9, 2016/03


 被引用回数:11 パーセンタイル:32.93(Multidisciplinary Sciences)

We investigate the local electronic structure and magnetic properties of the group-IV-based ferromagnetic semiconductor, Ge$$_{1-x}$$Fe$$_{x}$$ (GeFe), using soft X-ray magnetic circular dichroism. Our results show that the doped Fe 3$$d$$ electrons are strongly hybridized with the Ge 4$$p$$ states, and have a large orbital magnetic moment relative to the spin magnetic moment, namely $$m_{rm orb}$$/$$m_{rm spin}$$ $$approx$$ 0.1. We find that nanoscale local ferromagnetic regions, which are formed through ferromagnetic exchange interactions in the high-Fe-content regions of the GeFe films, exist even at room temperature, well above the Curie temperature of 20 - 100K. We observe the intriguing nanoscale expansion of the local ferromagnetic regions with decreasing temperature, followed by a transition of the entire film into a ferromagnetic state at the Curie temperature.


Operation and commissioning of IFMIF (International Fusion Materials Irradiation Facility) LIPAc injector

奥村 義和; Gobin, R.*; Knaster, J.*; Heidinger, R.*; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; et al.

Review of Scientific Instruments, 87(2), p.02A739_1 - 02A739_3, 2016/02

 被引用回数:5 パーセンタイル:55.4(Instruments & Instrumentation)



Measurement of ion species in high current ECR H$$^+$$/D$$^+$$ ion source for IFMIF (International Fusion Materials Irradiation Facility)

神藤 勝啓; Sen$'e$e, F.*; Ayala, J.-M.*; Bolzon, B.*; Chauvin, N.*; Gobin, R.*; 一宮 亮; 伊原 彰; 池田 幸治; 春日井 敦; et al.

Review of Scientific Instruments, 87(2), p.02A727_1 - 02A727_3, 2016/02

 被引用回数:5 パーセンタイル:55.4(Instruments & Instrumentation)

A high current ECR ion source producing 140 mA/100 keV D$$^+$$ ion beams for IFMIF accelerator is now under commissioning at Rokkasho in Japan, under the framework of ITER Broader Approach (BA) activities. The ion source for IFMIF is required to produce positive deuterium ion beams with a high D$$^+$$ ratio. After the mass separation in LEBT consisting of two solenoids, the D$$^+$$ ratio should be higher than 95 % with less molecular ions and impurity ions at the entrance of RFQ linac to be installed downstream. The ion species have been measured by Doppler shift spectroscopy between the two solenoids. With hydrogen operation in pulsed and CW modes, the H$$^+$$ ratio increases with RF power or plasma density and reached 80% at 160 mA/100 keV. The value was compared with that derived from the emittance diagram for each ion species measured by an Alison scanner installed nearby the viewport for the spectroscopy in the LEBT. It was found that the spectroscopy gives lower H$$^+$$ ratio than the emittance measurement.


Spin hydrodynamic generation

高橋 遼*; 松尾 衛; 小野 正雄; 針井 一哉; 中堂 博之; 岡安 悟; 家田 淳一; 高橋 三郎*; 前川 禎通; 齊藤 英治

Nature Physics, 12, p.52 - 56, 2016/01

 被引用回数:33 パーセンタイル:7.55(Physics, Multidisciplinary)

Magnetohydrodynamic generation is the conversion of fluid kinetic energy into electricity. Such conversion, which has been applied to various types of electric power generation, is driven by the Lorentz force acting on charged particles and thus a magnetic field is necessary. On the other hand, recent studies of spintronics have revealed the similarity between the function of a magnetic field and that of spin-orbit interactions in condensed matter. This suggests the existence of an undiscovered route to realize the conversion of fluid dynamics into electricity without using magnetic fields. Here we show electric voltage generation from fluid dynamics free from magnetic fields; we excited liquid-metal flows in a narrow channel and observed longitudinal voltage generation in the liquid. This voltage has nothing to do with electrification or thermoelectric effects, but turned out to follow a universal scaling rule based on a spin-mediated scenario. The result shows that the observed voltage is caused by spin-current generation from a fluid motion: spin hydrodynamic generation. The observed phenomenon allows us to make mechanical spin-current and electric generators, opening a door to fluid spintronics.


Magnetization process of the $$n$$-type ferromagnetic semiconductor (In,Fe)As:Be studied by X-ray magnetic circular dichroism

坂本 祥哉*; Anh, L. D.*; Hai, P. N.*; 芝田 悟朗*; 竹田 幸治; 小林 正起*; 高橋 文雄*; 小出 常晴*; 田中 雅明*; 藤森 淳*

Physical Review B, 93(3), p.035203_1 - 035203_6, 2016/01


 被引用回数:7 パーセンタイル:47.85(Materials Science, Multidisciplinary)

In order to investigate the mechanism of ferromagnetic ordering in the new $$n$$-type magnetic semiconductor (In,Fe)As codoped with Be, we have performed X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) studies. The spectral line shapes suggest that the ferromagnetism is intrinsic, originating from Fe atoms incorporated into the zinc-blende-type InAs lattice. The magnetization curves of Fe measured by XMCD were well reproduced by the superposition of a Langevin function representing superparamagnetic (SPM) behavior of nanoscale ferromagnetic domains and a $$T$$-linear function representing Curie-Weiss paramagnetism even much above the Curie temperatures. The data at 20 K showed a deviation from the Langevin behavior, suggesting a gradual establishment of macroscopic ferromagnetism on lowering temperature. The existence of nanoscale ferromagnetic domains indicated by the SPM behavior suggests spatial fluctuations of Fe concentration on the nanoscale.

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