JOPSS:検索結果一覧

論文

Probing deformation behavior of a refractory high-entropy alloy using neutron diffraction

Zhou, Y.*; Song, W.*; Zhang, F.*; Wu, Y.*; Lei, Z.*; Jiao, M.*; Zhang, X.*; Dong, J.*; Zhang, Y.*; Yang, M.*; et al.

Journal of Alloys and Compounds, 971, p.172635_1 - 172635_7, 2024/01

https://doi.org/10.1016/j.jallcom.2023.172635

被引用回数：0 パーセンタイル：0(Chemistry, Physical)

The grain orientation-dependent lattice strain evolution of a (TiZrHfNb) $_{98}$ refractory high-entropy alloy (HEA) during tensile loading has been investigated using neutron diffraction. The equivalent strain-hardening rate of each of the primary -oriented grain families was found to be relatively low, manifesting the macroscopically weak work-hardening ability of such a body-centered cubic (BCC)-structured HEA. This finding is indicative of a dislocation planar slip mode that is confined in a few single-slip planes and leads to in-plane softening by high pile-up stresses.

論文

Synergistic hybrid electrocatalysts of platinum alloy and single-atom platinum for an efficient and durable oxygen reduction reaction

Liu, B.*; Feng, R.*; Busch, M.*; Wang, S.*; Wu, H.*; Liu, P.*; Gu, J.*; Bahadoran, A.*; 松村大樹; 辻卓也; et al.

ACS Nano, 16(9), p.14121 - 14133, 2022/09

https://doi.org/10.1021/acsnano.2c04077

被引用回数：51 パーセンタイル：98.66(Chemistry, Multidisciplinary)

Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing H $_{2}$ O $_{2}$ in catalyzing the oxygen reduction reaction (ORR). Here, we demonstrate that anchoring platinum alloys on single-atom Pt-decorated carbon (Pt- SAC) surmounts their inherent deficiencies, thereby enabling a complete four-electron ORR pathway catalysis with high efficiency and durability. Pt $_{3}$ Co@Pt-SAC demonstrates an exceptional mass and specific activities 1 order of magnitude higher than those of commercial Pt/C. They are durable throughout 50000 cycles, showing only a 10 mV decay in halfwave potential. The superior durability is attributed to the shielding effect of the Pt-SAC coating, which significantly mitigates the dissolution of Pt $_{3}$ Co cores.

論文

Tracer diffusion coefficients measurements on LaPO $_{4}$ -dispersed LATP by means of neutron radiography

Song, F.*; Chen, H.*; 林田洋寿*; 甲斐哲也; 篠原武尚; 薮塚武史*; 八尾健*; 高井茂臣*

Solid State Ionics, 377, p.115873_1 - 115873_6, 2022/04

https://doi.org/10.1016/j.ssi.2022.115873

被引用回数：2 パーセンタイル：28.85(Chemistry, Physical)

Lithium tracer diffusion coefficients have been measured in Li $_{1.3}$ Al $_{0.3}$ Ti $_{1.7}$ (PO) (LATP) and LATP - LaPO composite solid electrolytes in the temperature range between 300 $^{circ}$ C and 500 $^{circ}$ C by means of neutron radiography technique that utilizes the difference in neutron attenuation of Li and Li isotopes. The diffusion coefficient of LATP - LaPO composite is higher than that of pristine LATP, although the difference is much smaller than that estimated from the room temperature conductivity. This suggests that the bulk diffusion becomes the predominant diffusion mechanism at 300 $^{circ}$ C to 500 $^{circ}$ C instead of the diffusion along the space charge layer formed around the LaPO dispersants.

論文

Comparison of heavy-ion transport simulations; Collision integral with pions and resonances in a box

小野章*; Xu, J.*; Colonna, M.*; Danielewicz, P.*; Ko, C. M.*; Tsang, M. B.*; Wang, Y,-J.*; Wolter, H.*; Zhang, Y.-X.*; Chen, L.-W.*; et al.

Physical Review C, 100(4), p.044617_1 - 044617_35, 2019/10

AA2019-0025.pdf:2.76MB

https://doi.org/10.1103/PhysRevC.100.044617

被引用回数：60 パーセンタイル：98.59(Physics, Nuclear)

2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究では、辺の長さが20fmの直方体に320個の中性子と陽子をランダム配置し、それらが70fm/cの間に起こす散乱の回数やエネルギーを計算した。ここでは、特にパイオンやその前駆体であるデルタ共鳴の生成に注目して比較を行った。参加コードは、個々の粒子の時間発展を追うQMD型コードと、粒子の位置や運動量の確率分布を決めておき、散乱や崩壊が発生したときそれらを乱数サンプリングするBUU型コードがあり、発表者が用いたJQMDは前者に属する。本研究により、計算における時間刻みが各コードによる結果の差の主な原因であることが分かった。さらに、今後のJQMDの改良方針の策定に有益な知見を得ることができた。

論文

Comparison of heavy-ion transport simulations; Collision integral in a box

Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; 小野章*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.

Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03

https://doi.org/10.1103/PhysRevC.97.034625

被引用回数：100 パーセンタイル：99.11(Physics, Nuclear)

2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究はモデル間の共通点と差異を明らかにし、各モデルの問題点を明らかにした。比較において、辺の長さが20fmの直方体に320個の中性子と320個の陽子をランダム配置し、それらが時間発展に伴って起こす散乱の回数や散乱時のエネルギーなどを計算する条件が設定された。また、結果以外にも、理論モデルを構成するアルゴリズムについても比較を行った。発表者は重イオン核反応モデルJQMD(JAERI Quantum Molecular Dynamics)を用いて計算を行い、世界で開発されている15の計算コードによる計算結果と比較した。コードアルゴリズムの比較では、JQMDは必ず陽子から優先的に衝突確率を計算し、その後に中性子の衝突を計算するため、物理描像の妥当性が指摘された。一方、JQMDは他のモデルとほぼ同じ計算結果を出すことも判明した。衝突回数や運動量の計算値が平均から2倍以上乖離するモデルもある中で、JQMDは本計算条件で安定した性能を発揮することが確認された。

論文

The Application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Ramebck, H.*; Nelwamondo, A. N.*; Kotze, D.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.425 - 434, 2018/02

https://doi.org/10.1007/s10967-017-5680-5

被引用回数：14 パーセンタイル：81.29(Chemistry, Analytical)

最新の核鑑識国際共同試料分析演習では、低濃縮ウラン試料について、10か国の核鑑識ラボラトリーが精製年代測定を実施して良好な結果を得た。これらの測定のうち、3つの異なる核種ペアを用いた精製年代測定も実施された。10か国の核鑑識ラボラトリーが提出した精製年代測定の結果は、実際の精製日と概ね一致した。また、質量分析法による結果は、放射線計測法を用いたものに比べて、高精度な結果を示した。さらに、一部のラボラトリーによって示された $^{235}$ U- $^{231}$ Pa法と $^{234}$ U- $^{230}$ Th法による精製年代測定の結果の一致は、結果の確証性を高めた。

論文

Electronic structure and magnetism of the diluted magnetic semiconductor Fe-doped ZnO nanoparticles

片岡隆史*; 小林正起*; 坂本勇太*; Song, G. S.*; 藤森淳*; Chang, F.-H.*; Lin, H.-J.*; Huang, D. J.*; Chen, C. T.*; 大河内拓雄*; et al.

Journal of Applied Physics, 107(3), p.033718_1 - 033718_7, 2010/02

AA2009-0977.pdf:1.0MB

https://doi.org/10.1063/1.3294620

被引用回数：54 パーセンタイル：86.07(Physics, Applied)

We have studied the electronic structure of Fe-doped ZnO nanoparticles, which have been reported to show ferromagnetism at room temperature, by X-ray photoemission spectroscopy (XPS), resonant photoemission spectroscopy (RPES), X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). From the experimental and cluster-model calculation results, we find that Fe atoms are predominantly in the Fe $^{3+}$ ionic state with mixture of a small amount of Fe $^{2+}$ and that Fe $^{3+}$ ions are dominant in the surface region of the nanoparticles. It is shown that the room temperature ferromagnetism in the Fe-doped ZnO nanoparticles is primarily originated from the antiferromagnetic coupling between unequal amounts of Fe $^{3+}$ ions occupying two sets of nonequivalent positions in the region of the XMCD probing depth of 2-3 nm.

論文

Electronic structure of Ga $_{1-x}$ Cr $_{x}$ N and Si-doping effects studied by photoemission and X-ray absorption spectroscopy

Song, G.*; 小林正起*; Hwang, J. I.*; 片岡隆*; 滝沢優*; 藤森淳; 大河内拓雄; 竹田幸治; 岡根哲夫; 斎藤祐児; et al.

Physical Review B, 78(3), p.033304_1 - 033304_4, 2008/07

https://doi.org/10.1103/PhysRevB.78.033304

被引用回数：8 パーセンタイル：37.23(Materials Science, Multidisciplinary)

The electronic structure of the magnetic semiconductor Ga $_{1-x}$ Cr $_{x}$ N, and the effect of Si doping on it have been investigated by photoemission and soft X-ray absorption spectroscopy. We have confirmed that Cr in GaN is predominantly trivalent when substituting for Ga and that Cr 3 states appear within the band gap of GaN just above the N 2-derived valence-band maximum. As a result of Si doping, downward shifts of the core levels (except for Cr 2) and the formation of new states near the Fermi level were observed, which we attribute to the upward chemical-potential shift and the formation of a small amount of Cr $^{2+}$ species caused by electron doping. Possibility of Cr-rich cluster growth by Si doping are discussed based on the spectroscopic and magnetization data.

口頭

Water/ice identification in a model PEFC using energy-selective high-resolution neutron imaging

Song, F.; 樋口雄紀*; 日比章五*; 吉宗航*; 加藤悟*; 篠原武尚

no journal, ,

In this work, we have applied the energy-selective neutron radiography to visualize the freezing and thawing of water in different cavity layers of a fuel cell by taking cross-sectional neutron transmission images, as a preliminary experiment for further operando water/ice identification observations on PEFCs. A miniature size of a fuel cell, which consisted of gas diffusion layers (GDLs) and aluminum frames with gas channels produced by 3D printing technique, was prepared as a model cell sample. This model fuel cell was filled with water and cooled by a Peltier cooler down to -10 degree C. Consecutive high-resolution energy-selective neutron imaging was conducted throughout the freezing process at the RADEN instrument in J-PARC MLF. By taking the ratio of logarithms of neutron transmission between long and short wavelength neutrons, we defined a water/ice identification parameter to confirm freezing of water within the cell. This parameter was spatially resolved on the neutron transmission images to map the water/ice distribution in each layer of the model fuel cell as it was cooled to sub-zero temperatures. In the presentation, we will discuss the spatial and temporal resolution capacities of the high-resolution energy-selective neutron imaging at the RADEN instrument, and show results of the water/ice identification experiments on the cross-sectional observation of the PEFC.

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