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Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 他4名*
Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07
被引用回数：1 パーセンタイル：75.81(Materials Science, Multidisciplinary)Face-centered cubic (FCC) equi-atomic multi-principal element alloys (MPEAs) exhibit excellent mechanical properties from cryogenic to room temperatures. At room temperature, deformation is dominated by dislocation slip, while at cryogenic temperatures (CTs), reduced stacking fault energy enhances strain hardening with twinning. This study uses in-situ neutron diffraction to analyze the temperature-dependent deformation behavior of Al
(CoNiV)
, a dual-phase (FCC/BCC) medium-entropy alloy (MEA). At liquid nitrogen temperature (LNT), deformation twinning in the FCC matrix leads to additional strain hardening through the dynamic Hall-Petch effect, giving the appearance of improved strengthening at LNT. In contrast, BCC precipitates show dislocation slip at both 77 K and 298 K, with temperature-dependent lattice friction stress playing a significant role in strengthening. The study enhances understanding of deformation behaviors and provides insights for future alloy design.
Qu, H.*; Gong, W.; 川崎 卓郎; Harjo, S.; Wei, D.*; 他4名*
Science China; Technological Sciences, 68(6), p.1620201_1 - 1620201_10, 2025/06
被引用回数：0 パーセンタイル：0.00(Engineering, Multidisciplinary)Precipitation-strengthened medium-entropy alloys (MEAs) often display an excellent balance of strength and ductility. However, the influence of temperature on their mechanical properties and plastic deformation mechanism requires further exploration. This study examines the tensile behavior and plastic deformation mechanisms of the (CoCrNi)
Ti
Al alloy at 298, 77, and 20 K using in-situ neutron diffraction and electron microscopy methods. Lower temperatures result in improved mechanical performance, as indicated by an increase in yield strength, ultimate tensile strength (UTS), and elongation. At lower temperatures, a larger number of dislocations and stacking faults form, enhancing the alloy's strain hardening ability. Notably, dislocations exhibit wavy morphologies at 298 K, whereas planar behavior becomes predominant at 20 and 77 K. No FCC
HCP phase transformation is detected, a behavior that contrasts with the CoCrNi MEA under deformation at 20 K. Additionally, the interaction between dislocations and L12 nanoparticles exhibited temperature dependence, suggesting the need for future investigations. This study offers valuable insights for advancing the design of high-performance alloys suitable for cryogenic applications.
江頭 尚弥*; 松田 朋己*; 奥地 拓生*; 瀬戸 雄介*; 伊藤 佑介*; 菖蒲 敬久; 中新 信彦*; 佐野 智一*; 他4名*
Journal of Applied Physics, 137(10), p.105903_1 - 105903_8, 2025/03
被引用回数：1 パーセンタイル：76.22(Physics, Applied)Femtosecond laser-driven shock waves exhibit characteristic features that form distinctive microstructures not formed by plate impacts or nanosecond laser-driven shock waves. A key to understanding this phenomenon is understanding the lattice behavior inside the shock front, which is the boundary between the ambient and shock compression states. However, direct measurements of the lattice spacing inside a femtosecond laser-driven shock front have not yet been performed. Here, we report 
measurements of lattice spacing using X-ray free electron laser diffraction with a pulse width of 
10 fs during the shock rise in single-crystal copper irradiated directly in air with a femtosecond laser pulse on the order of 10
W/cm
at a pulse width of 101 fs. The lattice spacing of the femtosecond laser-irradiated single-crystal Cu (002) plane starts to compress 6.3 ps after femtosecond-laser irradiation. It takes 15.7 ps for the plane to reach peak compression, at which point the compressive elastic-strain is 24.3%. Therefore, the shock front was found to form at an elastic compressive strain rate of 1.55
10
/s in this shock-driving situation. It is suggested that the initiation of plasticity under such ultrafast deformation at the most elastic compression is based on both dislocation multiplication and dislocation generation mechanisms.
小澤 孝拓*; 福谷 克之; 他4名*
Journal of Vacuum Science and Technology A, 42(2), p.023402_1 - 023402_6, 2024/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Coatings & Films)We synthesized an epitaxial film of high-entropy perovskite oxide (HEPO) consisting of three elements (Ca, Sr, Ba) in the A site and 12 elements (Si, Ti, Cr, Mn, Fe, Co, Ni, Ge, Zr, Sn, Ce, Hf) in the B site of ABO, and investigated hydrogen absorption properties in the HEPO film. The hydrogen depth profile was measured by nuclear reaction analysis via the 
H(
N, 
)
C reaction, showing the hydrogen absorption in the HEPO film with a maximum atomic concentration of 0.3 in the ABO unit. The diffusion coefficient of H in the film was analyzed from the H depth profile, and the activation barrier for diffusion was estimated to be (0.54
0.13) eV. An absorption band was observed at 3290 cm 
in the infrared absorption spectrum, which corresponds to the O-H stretching vibration. Simultaneous measurements of nuclear reaction and resistance revealed that the HEPO film remained electrically insulating regardless of the hydrogen concentration. We demonstrated that hydrogen is incorporated in HEPO forming OH species while keeping HEPO electrically insulating.
小澤 孝拓*; 福谷 克之; 他4名*
Journal of Physics and Chemistry of Solids, 185, p.111741_1 - 111741_7, 2024/02
被引用回数：3 パーセンタイル：28.87(Chemistry, Multidisciplinary)Hydrogen (H), the lightest element, exhibits quantum nature. Because the quantum tunneling is almost independent of temperature, H diffusion shows a transition from thermal hopping to quantum tunneling at low temperature. The role of the nuclear quantum effects on H diffusion, however, has not been clarified around the crossover region. Hence, we elucidate the hopping mechanism at intermediate temperature by a combination of accurate experimental data on H hopping rates and theoretical calculations for quantum states of H. We derived H hopping rates in Pd from the resistance evolution due to the H ordering associated with the 50 K anomaly. A gradual transition from thermal hopping to quantum tunneling was observed around 65 K. Three-dimensional quantum-mechanical analysis for the H quantum states revealed that the gradual transition is attributed to the resonant tunneling between the discrete vibrational states in the octahedral site and the tetrahedral site via the thermal vibrational excitation. Based on the results at different H concentrations and deuterium, we demonstrated that the tunneling rate is tuned by energy level matching and the resonance nature is manifested as the abruptness of the transition from thermal to quantum hopping.
O
(111) surfaces浅川 寛太*; 福谷 克之; 他4名*
Physical Review B, 99(8), p.085442_1 - 085442_8, 2019/02
被引用回数：7 パーセンタイル：30.59(Materials Science, Multidisciplinary)The adsorption of O and H atoms on the FeO(111) surface was investigated using ultraviolet photoemission spectroscopy (UPS) and first-principles calculations. On the FeA1-terminated surface, H adsorption decreases the work function without changing the density of states near the Fermi level. The density of states near the Fermi level decreases by O adsorption. On the O/FeA1-terminated surface, H adsorption dramatically increases the density of states near the Fermi level, indicating that the Fe 3
state is modified. The first-principles calculations showed that the electronic structure of the surface FeA on the FeA1-terminated surface is half metallic with its spin up forming an isolated spin-polarized conductive layer. By O adsorption, the up-spin band at the Fermi level of the surface FeA site is removed, and the Fermi level of the surface FeA moves to the down-spin 
band. By subsequent H adsorption, electrons are doped to the FeA1 site, and the surface FeA1 layer becomes semiconducting. These results indicate that the charge and spin structure is modulated by O and H adsorption.
笹尾 信之*; 和田 幸男; 河野 秀作; 他4名*
PNC TN8410 89-061, 44 Pages, 1989/11
高温酸化物超電導体の特性向上を図るためには均一組成、単一相でよりファインな原料粉末を得ることが求められる。また、試料合成の迅速化を図ることは、今後の研究展開の拡大等の点で重要である。本研究は迅速に特性の優れた高温酸化物超電導体を合成するための手法を確立することを目的として、固相反応法、シュウ酸エステルによる加水分解法、マイクロ波による硝酸塩共分解法の三つの合成手法により、約110Kの臨界温度を有するBi-Pb-Sr-Ca-Cu-O系の酸化物超電導体を合成し、特性評価を行って三つの手法の比較評価を行ったものである。 その結果、(1)三つの合成手法によりTcoff=103
107KのBi-Pb系超電導体が得られた。(2)三つの合成手法で得られた試料の電気抵抗及び帯磁率の温度特性はほぼ同じ特性を示した。(3)シュウ酸ジメチルの化水分解法は三つの手法の中で高温の単一相を安定して生成するための合成手法として最適である。(4)マイクロ波加熱分解法は三つの手法の中で迅速合成法として有望である等の見通しを得た。
磯前 勇一*; 他4名*
PNC TN8440 89-003, 92 Pages, 1989/02
1.安全管理業務概要 2.安全管理一般 2.1規定・規則類の整備 2.2安全衛生委員会等の活動 2.3教育訓練実施状況 2.4安全パトロール,安全点検等の実施状況 2.5監督官庁への許認可申請及び報告等 2.6品質保証活動 2.7安全管理技術開発推進委員会活動 3.放射線管理 3.1放射線管理第一課所掌施設 3.2放射線管理第二課所掌施設 3.3放射線管理用機器の管理 3.4マスクマンテスト実施状況 3.5技術開発等 4.環境安全 4.1環境監視業務 4.2放出放射能監視業務 4.3内部被曝管理分析(バイオアッセイ) 4.4技術開発等 5.個人被曝管理 5.1外部被曝管理 5.2内部被曝管理 5.3被曝線量測定結果の報告,通知,登録関係業務 5.4技術開発等 5.5品質管理 5.6その他の特記事項 6.外部発表等 6.1外部発表(学会論文発表,外部機関誌論文発表,その他の外部発表) 7.健康管理 7.1健康診断 7.2衛生管理者会議 7.3職場巡視 7.4緊急医療 7.5内科,歯科診療および鍼・マッサージ
市川 真也; Gubler, P.; 佐甲 博之; 他4名*
no journal, ,
KEK-PS E325実験並びにJ-PARC E16実験では、pA反応を用い原子核内にベクター中間子を生成し、その電子陽電子対崩壊から原子核中における質量スペクトルを測定する。pA反応が起きると反応を起こした原子核はある時間スケールで破砕しうるがその影響はこれまでの解析には取り入れられてこなかった。講演者は新たにPHSDと呼ばれる輸送計算を導入し、ベクター中間子が崩壊時に感じる密度をシミュレーションして解析に取り入れることを考案した。本講演ではこの解析の現状について報告する。
Siの一軸圧下でのNMR/NQR神戸 振作; 石飛 尊之; 芳賀 芳範; 酒井 宏典; 徳永 陽; 他4名*
no journal, ,
URuSiの隠れた秩序解明のために一軸圧下でのRu, Si NMR/NQR測定結果について報告する。
