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Cao, T.*; Wei, D.*; Gong, W.; 川崎 卓郎; Harjo, S.; 他10名*
Materials Science and Engineering A, 940, p.148534_1 - 148534_16, 2025/09
被引用回数：0The thermal stability of microstructure and mechanical performance is crucial for the industrial application of laser powder bed fusion (LPBF) superalloy components in gas turbines and jet engines. This work investigated the microstructural evolution and strengthening mechanism of LPBF Mar-M509 cobalt-based superalloy before and after thermal exposure at 1200 
C using multi-scale microstructural characterization and in situ neutron diffraction tensile testing. The as-built Mar-M509 superalloy exhibited a heterogeneous microstructural features with coarse columnar and fine equiaxed grains, both containing dendritic and cellular substructures enriched with nanoscale carbides and high-density dislocations. The ultra high strength of the as-built sample was primarily attributed to dislocation-precipitation synergistic strengthening. After thermal exposure at 1200 C for 4 h, the dendritic and cellular substructures disappeared and the dislocation density decreased significantly. This study reveals the microstructural evolution and instability of LPBF Mar-M509 superalloy under high-temperature exposure and the impacts on mechanical properties, which provides critical support for the development of cobalt-based superalloys in high-temperature application fields.
関 祐一*; 藤森 伸一; 他10名*
Physical Review Letters, 135(4), p.046402_1 - 046402_7, 2025/07
In transition-metal compounds, the transition-metal d electrons play an important role in their physical properties; however, the effects of the electron correlation between the ligand p electrons have not been clear yet. In this Letter, the Ru 4d and O 2p partial density of states (PDOS) in transition-metal oxide SrRuO involving Weyl fermions are investigated by resonant photoemission spectroscopy. The observations demonstrate that the O 2p PDOS is distorted from that predicted by first-principles calculations than the Ru 4d PDOS. The results indicate that the electron correlation in the ligand orbitals will be important to understand the electronic structure of the p-d hybridized state in strongly correlated electron systems, even with topological states.
小杉 美央子*; 吉川 貴史; 齊藤 英治; 他10名*
ACS Applied Materials & Interfaces, 16(46), p.64190 - 64196, 2024/11
被引用回数：2 パーセンタイル：34.28(Nanoscience & Nanotechnology)Atom-vacancy-defects present in various materials yield numerous interesting physical phenomena, even obstructing high performance in some cases. On the other hand, their valuable applications to novel devices, such as nitrogen vacancy centers in diamond for quantum bits, have gathered significant attention. In particular, these tendencies become more substantial in two-dimensional (2D) (atomically) thin van der Waals layers. However, correlations with various kinds of atom defects are still under exploration. Herein, we find the stochastic behaviors of large hysteresis loops with strong photoresponse in the static electrical properties in few-atom layer semiconductors, molybdenum disulfide (MoS
). The temperature dependence and transmission electron microscopy reveal that they arise from pairs of two neighboring in-plane S-vacancy defects, which predominantly present only around the interface at the MoS flake/substrate, with activation energies similar to 0.35 eV. The low-frequency (
) (LF) noise measurements clarify a high f shift in the two 1/ 2-dependent regimes, implying stochastic behaviors of electric charges through the S-vacancy pairs with high-speed charge(spin) transitions across low kinetic energy barriers between narrow discrete states. The shallow energy sates are formed from the highly uniform S-vacancy pairs interacting with Mo atoms, which act like quantum dots. The observed stochastic operation holds promise for various application, particularly for probabilistic neuromorphic computation in artificial intelligence.
Kiliyankil, V. A.*; 福谷 克之; 他10名*
Journal of Materials Chemistry A, 12(42), p.28731 - 28743, 2024/10
被引用回数：0 パーセンタイル：0.00(Chemistry, Physical)The hydrogen evolution reaction (HER) on platinum (Pt) electrocatalysts involves the generation of hydrogen atoms and the formation of hydrogen molecules. It is commonly believed that the sites on the surfaces of the terrace (111, 110, and 100) domains are responsible for the formation of hydrogen molecules. However, the electrochemistry of the hydrogen atom generation is not well understood. We created edge-rich platinum electrocatalysts using nano-fabrics comprising entire single-walled carbon nanotubes (SWCNTs) as templates and supports. We then conducted the HER on the edge-rich Pt/SWCNT hybridized electrocatalysts and gained new insights into the electrochemical properties and functions of the edge sites. We propose that the edge sites are oxidized and serve two important functions: they act as atomic barriers, allowing electrons to accumulate within the terrace (111, 110, and 100) domains, and they transfer the electrons to the hydronium ions in the electrical double layer through discharge. Enhancing the discharge capability of the electrocatalysts is an efficient way to reduce the amount of platinum required, and this can be applied to various precious metal-based electrocatalysts to enhance their electrocatalytic activities and durability.
Mo, 
Mo, and 
MoKumar, V.*; Chapman, R.*; Ollier, J.*; Orlandi, R.; Smith, J. F.*; Spohr, K.-M.*; Torres, D. A.*; Wady, P.*; 他10名*
Physical Review C, 110(4), p.044308_1 - 044308_18, 2024/10
被引用回数：2 パーセンタイル：61.39(Physics, Nuclear)Excited states of the molybdenum isotopes 
Mo were populated in two experiments which used fusion-fission and binary grazing reactions. In the first experiment, the GASP array of Ge detectors was used to detect 
rays from fusion-fission products from the 
S + 
Yb reaction at 230 MeV. In the multinucleon transfer experiment, a 530-MeV beam of 
Zr ions was incident on a thin 
Sn target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and their associated rays detected using the CLARA array of Clover detectors. Previously known bands were extended in all isotopes, and a new g
band was established in Mo. The observed level schemes were compared with shell-model calculations, which reproduce the general features of the energy spectrum of excited states of Mo, Mo, and Mo, although not in detail. For the h
negative-parity decay sequences of the three isotopes studied, evidence is presented for nuclear shape changes with increasing neutron number.
= 82 shell closureZhang, W. Q.*; Andreyev, A. N.; 他10名*
Physical Review C, 110(4), p.044301_1 - 044301_7, 2024/10
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Based on the 
values deduced from the linear extrapolations along isotopic chains and on the universal decay law, the proton- and 
-decay partial half-lives are calculated for odd-, even-
neutron-deficient Bi-Pa isotopes. Eight proton-emission states in five new isotopes are suggested. The calculated half-lives for the 1/2
states in 
Bi and 
At are around 100 ns, too short to be studied using the recoil separator setups, which strongly encourages the development of new experimental techniques and devices to search for new submicrosecond proton-emitting nuclei.
U and 
ThFilipescu, D.*; Gheorghe, I.*; Goriely, S.*; 西尾 勝久; 宇都宮 弘章*; 洲嵜 ふみ; 廣瀬 健太郎; 他10名*
Physical Review C, 109(4), p.044602_1 - 044602_23, 2024/04
被引用回数：3 パーセンタイル：74.10(Physics, Nuclear)New measurements of photofission and photoneutron reactions on U and Th in the Giant Dipole Resonance (GDR) energy region have been performed at the laser Compton-scattering -ray source of the NewSUBARU synchrotron radiation facility. The photoneutron (
) with 
= 1-3 and photofission (
) reactions have been discriminated by considering a Gaussian distribution of prompt-fission-neutron (PFN) multiplicities predicted by the theory of evaporation in sequential neutron emission from excited fission fragments. We report experimental (
), (
), (
) and () cross sections, average energies of PFNs and of(, 
) photoneutrons, as well as the mean number of PFNs per fission and the width of the PFNs multiplicity distribution. Based on these primary experimental results and combined with reasonable assumptions, we extract also the first- and second-chance fission contributions.
Ahn, J. K.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; 他10名*
Nuclear Instruments and Methods in Physics Research A, 1047, p.167775_1 - 167775_13, 2023/02
被引用回数：1 パーセンタイル：15.32(Instruments & Instrumentation)We have constructed a conduction-cooled superconducting dipole magnet for the Hyperon spectrometer at Japan Proton Accelerator Research Complex (J-PARC). The magnet is a Helmholtz-type dipole magnet with two circular coils with a radius of 500 mm separated by 500 mm. It provides a uniform magnetic field of 1.0 T or higher in a volume of 
mm 
600 mm, covering the drift region of a time projection chamber (TPC). Owing to the target location inside the TPC, the Hyperon spectrometer has a broad angular coverage with a nearly 
solid angle. We have successfully excited the magnet up to 1.3 T. At 1.0 T, we operated it stably for more than 1 week in single-magnet configuration and double-magnet configuration with a normal-conducting 0.7-T dipole magnet located 30 cm apart. The measured magnetic field distribution in the TPC volume is consistent with the calculated field map.
nuclear modification at backward and forward rapidity in 
, Al, and Au collisions at 
GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他310名*
Physical Review C, 105(6), p.064912_1 - 064912_15, 2022/06
被引用回数：18 パーセンタイル：90.69(Physics, Nuclear)Suppression of the 
nuclear-modification factor has been seen as a trademark signature of final-state effects in large collision systems for decades. In small systems, the nuclear modification was attributed to cold-nuclear-matter effects until the observation of strong differential suppression of the state in 
collisions suggested the presence of final-state effects. Results of and measurements in the dimuon decay channel are presented here for , Al, and Au collision systems at GeV. The results are predominantly shown in the form of the nuclear-modification factor, 
, the ratio of the invariant yield per nucleon-nucleon collision in collisions of proton on target nucleus to that in collisions. Measurements of the and nuclear-modification factor are compared with shadowing and transport-model predictions, as well as to complementary measurements at Large-Hadron-Collider energies.
Mg
Ni
Mn
O (0 
x 0.07) from electrochemical and muon spin relaxation studiesMa, L. A.*; 杉山 純; 他10名*
Physical Chemistry Chemical Physics, 23(42), p.24478 - 24486, 2021/11
被引用回数：10 パーセンタイル：53.92(Chemistry, Physical)Sodium transition metal oxides with a layered structure are one of the most widely studied cathode materials for Na ion batteries. Since the mobility of Na in such cathode materials is a key factor that governs the performance of material, electrochemical and muon spin rotation and relaxation techniques are here used to reveal the Na ion mobility in a P2-type P2-type NaMgNiMnO (x = 0, 0.02, 0.05 and 0.07) cathode material. Combining electrochemical techniques such as galvanostatic cycling, cyclic voltammetry with 
SR, we have successfully extracted both self-diffusion and chemical-diffusion under a potential gradient, which are essential to understand the electrode material from an atomic-scale viewpoint. The results indicate that a small amount of Mg substitution has strong effects on the cycling performance and the Na mobility.
clarified with high-pressure 
SR杉山 純; 他10名*
Physical Review B, 101(17), p.174403_1 - 174403_10, 2020/05
ミュオンスピン緩和法により、擬一次元スピン系BaVSの粉末試料における磁気的性質を研究した。常圧では
=31K以下で不整合反強磁性秩序状態を示す。は、圧力が増加してもほぼ一定であるが、1.4GPa以上において急激に減少する。最終的には1.8GPaで消滅し、それ以上では金属相が安定化する。このは1.4GPa以上で生じる圧力誘起金属絶縁体転移温度に相当する。
Oset, E.*; 他10名*; 岡 眞
Acta Physica Polonica B, 47(2), p.357 - 365, 2016/02
被引用回数：3 パーセンタイル：25.43(Physics, Multidisciplinary)メソン複数個を含むエキゾチックハドロンに関する研究成果をレビューした。未発見の状態については、今後の実験による探索を示唆した。
Thalmeier, R.*; 谷田 聖; 他102名*
Journal of Instrumentation (Internet), 11(1), p.C01044_1 - C01044_10, 2016/01
被引用回数：2 パーセンタイル：9.91(Instruments & Instrumentation)The upgrade of the Belle II experiment plans to use a vertex detector based on two different technologies, DEPFET pixel (PXD) technology and double side silicon microstrip (SVD) technology. The vertex electronics are characterized by the topology of SVD bias that forces to design a sophisticated grounding because of the floating power scheme. The complex topology of the PXD power cable bundle may introduce some noise inside the vertex area. This paper presents a general overview of the EMC issues present in the vertex system, based on EMC tests on an SVD prototype and a study of noise propagation in the PXD cable bundle based on Multi-conductor transmission line theory.
都留 智仁; Lobzenko, I.; 椎原 良典*; Wei, D.*; 山下 真一郎; 板倉 充洋; 他10名*
no journal, ,
ハイエントロピー合金(HEA)は、5元素またはそれ以上の成分が高濃度で混合した結晶構造を持つ合金として定義される。FCC構造とBCC構造でそれぞれCoCrFeNiMn(Cantor)合金とZrNbTaTiHf(Senkov)合金という強度と延性を両立した合金系が発見されており、これらの組成を軸にさらに優れた合金系の開発が行われている。力学特性の向上に対する機構は、格子の局所ひずみに対応する平均二乗原子変位(MSAD)による効果に加えて、FCC構造では双晶形成、BCC構造では特異な転位運動が重要な役割を果たしている。本研究では、FCC構造とBCC構造を有するHEAを対象に、第一原理計算に基づくシミュレーションを用いて欠陥構造の諸特性について検討する。MoNbTaVWとZrNbTaTiHfの2つのBCC-HEAにおけるRandom構造と800KのMC計算から得られた短距離秩序を有する構造に対して、135のサイトに転位双極子が導入された際のエネルギーの分布を評価した。その結果、2つの合金ではMSADが大きく異なっており、格子のひずみが大きなZrNbTaTiHfでは転位の形成エネルギーが小さくなることがわかった。
