検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年
検索結果: 2761 件中 1件目~20件目を表示

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

選択した検索結果をダウンロード

論文

Quantitative analysis of microstructure evolution, stress partitioning and thermodynamics in the dynamic transformation of Fe-14Ni alloy

Li, L.*; 宮本 吾郎*; Zhang, Y.*; Li, M.*; 諸岡 聡; 及川 勝成*; 友田 陽*; 古原 忠*

Journal of Materials Science & Technology, 184, p.221 - 234, 2024/06

Dynamic transformation (DT) of austenite ($$gamma$$) to ferrite ($$alpha$$) in the hot deformation of various carbon steels was widely investigated. However, the nature of DT remains unclear due to the lack of quantitative analysis of stress partitioning between two phases and the uncertainty of local distribution of substitutional elements at the interface in multi-component carbon steels used in the previous studies. Therefore, in the present study, a binary Fe-Ni alloy with $$alpha$$+$$gamma$$ duplex microstructure in equilibrium was prepared and isothermally compressed in $$alpha$$+$$gamma$$ two-phase region to achieve quantitative analysis of microstructure evolution, stress partitioning and thermodynamics during DT. $$gamma$$ to $$alpha$$ DT during isothermal compression and $$alpha$$ to $$gamma$$ reverse transformation on isothermal annealing under unloaded condition after deformation were accompanied by Ni partitioning. The lattice strains during thermomechanical processing were obtained via in-situ neutron diffraction measurement, based on which the stress partitioning behavior between $$gamma$$ and $$alpha$$ was discussed by using the generalized Hooke's law. A thermodynamic framework for the isothermal deformation in solids was established based on the basic laws of thermodynamics, and it was shown that the total Helmholtz free energy change in the deformable material during the isothermal process should be smaller than the work done to the deformable material. Under the present thermodynamic framework, the microstructure evolution in the isothermal compression of Fe-14Ni alloy was well explained by considering the changes in chemical free energy, plastic and elastic energies and the work done to the material. In addition, the stabilization of the soft $$alpha$$ phase in Fe-14Ni alloy by deformation was rationalized since the $$gamma$$ to $$alpha$$ transformation decreased the total Helmholtz free energy by decreasing the elastic and dislocation energies.

論文

Distinguishing ion dynamics from muon diffusion in muon spin relaxation

伊藤 孝; 門野 良典*

Journal of the Physical Society of Japan, 93(4), p.044602_1 - 044602_7, 2024/04

We propose a model to describe the fluctuations in the internal magnetic field due to ion dynamics observed in muon spin relaxation ($$mu$$SR) by an Edwards-Anderson-type autocorrelation function that separates the quasi-static and dynamic components of the correlation by the parameter $$Q$$ (where $$0leq Qleq 1$$). Our Monte Carlo simulations for this model showed that the time evolution of muon spin polarization deviates significantly from the Kubo-Toyabe function. To further validate the model, the results of simulations were compared with the $$mu$$SR spectra observed in a hybrid organic-inorganic perovskite FAPbI$$_3$$ [with FA referring to HC(NH$$_2$$)$$_2$$], where local field fluctuations associated with the rotational motion of FA molecules and quasi-static fields from the PbI$$_3$$ lattice are presumed to coexist. The least-squares curve fitting showed reasonable agreement with the model with $$Q=0.947(3)$$, and the fluctuation frequency of the dynamical component was obtained. This result opens the door to the possibility of experimentally distinguishing fluctuations due to the dynamics of ions around muons from those due to the self-diffusion of muons. On the other hand, it suggests the need to carefully consider the spin relaxation function when applying $$mu$$SR to the issue of ion dynamics.

論文

Crystal-liquid duality driven ultralow two-channel thermal conductivity in $$alpha$$-MgAgSb

Li, J.*; Li, X.*; Zhang, Y.*; Zhu, J.*; Zhao, E.*; 古府 麻衣子; 中島 健次; Avdeev, M.*; Liu, P.-F.*; Sui, J.*; et al.

Applied Physics Reviews (Internet), 11(1), p.011406_1 - 011406_8, 2024/03

The desire for intrinsically low lattice thermal conductivity ($$kappa_L$$) in thermoelectrics motivates numerous efforts on understanding the microscopic mechanisms of heat transport in solids. Here, based on theoretical calculations, we demonstrate that $$alpha$$-MgAgSb hosts low-energy localized phonon bands and avoided crossing of the rattler modes, which coincides with the inelastic neutron scattering result. Using the two-channel lattice dynamical approach, we find, besides the conventional contribution ($$sim$$70% at 300 K) from particlelike phonons propagating, the coherence contribution dominated by the wavelike tunneling of phonons accounts for $$sim$$30% of total $$kappa_L$$ at 300 K. By considering dual contributions, our calculated room-temperature $$kappa_L$$ of 0.64 Wm$$^{-1}$$K$$^{-1}$$ well agrees with the experimental value of 0.63 Wm$$^{-1}$$K$$^{-1}$$. More importantly, our computations give a nonstandard $$kappa_L propto T^{-0.61}$$ dependence, perfectly explaining the abnormal temperature-trend of $$sim T^{-0.57}$$ in experiment for $$alpha$$-MgAgSb. By molecular dynamics simulation, we reveal that the structure simultaneously has soft crystalline sublattices with the metavalent bonding and fluctuating liquid-like sublattices with thermally induced large amplitude vibrations. These diverse forms of chemical bonding arouse mixed part-crystal part-liquid state, scatter strongly heat-carrying phonons, and finally produce extremely low $$kappa_L$$. The fundamental research from this study will accelerate the design of ultralow-$$kappa_L$$ materials for energy-conversion applications.

論文

Proton diffusion in liquid 1,2,3-triazole studied by incoherent quasi-elastic neutron scattering

篠原 佑也*; 岩下 拓哉*; 中西 真大*; Osti, N. C.*; 古府 麻衣子; 楡井 真実; Dmowski, W.*; 江上 毅*

Journal of Physical Chemistry B, 128(6), p.1544 - 1549, 2024/02

Improving the proton transport in polymer electrolytes impacts the performance of next-generation solid-state batteries. However, little is known about proton conductivity in nonaqueous systems due to the lack of an appropriate level of fundamental understanding. Here, we studied the proton transport in small molecules with dynamic hydrogen bonding, 1,2,3-triazole, as a model system of proton hopping in a nonaqueous environment using incoherent quasi-elastic neutron scattering. By using the jump-diffusion model, we identified the elementary jump-diffusion motion of protons at a much shorter length scale than those by nuclear magnetic resonance and impedance spectroscopy for the estimated long-range diffusion. In addition, a spatially restricted diffusive motion was observed, indicating that proton motion in 1,2,3-triazole is complex with various local correlated dynamics. These correlated dynamics will be important in elucidating the nature of the proton dynamics in nonaqueous systems.

論文

Development of 0.5 mm gauge size radial collimators for high-pressure neutron diffraction experiments at PLANET in J-PARC

服部 高典; 鈴木 浩二*; 三代 達也*; 伊藤 崇芳*; 町田 真一*

Nuclear Instruments and Methods in Physics Research A, 1059, p.168956_1 - 168956_9, 2024/02

見込み幅0.5mmのラジアルコリメータを高圧中性子回折実験用に特別に設計し、その性能と有効性を調べた。0.75mm, 1.5mm, 3.0mmのラジアルコリメータはそれぞれ0.50mm, 1.07mm, 2.78mmのみこみ幅を示した。3つのラジアルコリメータの透過率はすべて同等であった。Paris-Edinburgh(PE)プレスとdiamond anvil cell (DAC)を使用した評価では、見込み幅0.5mmラジアルコリメータを使用した場合、アンビル散乱はかなり減少し、サンプル/アンビル信号比はPEプレスとDACでそれぞれ0.5と2.0に達した。これらの結果は、見込み幅0.5mmラジアルコリメータが意図したとおりに製作され、高圧中性子回折実験(特に30GPaを超える実験)に有効であることを示している。今回作成されたラジアルコリメータの見込み幅は、これまで世界の中性子散乱実験用に製作されたものの中で、最も小さい見込み幅を持つものである。

論文

Composition dependence of bulk properties in the Co-intercalated transition metal dichalcogenide Co$$_{1/3}$$TaS$$_{2}$$

Park, P.*; Cho, W.*; Kim, C.*; An, Y.*; Avdeev, M.*; 飯田 一樹*; 梶本 亮一; Park, J.-G.*

Physical Review B, 109(6), p.L060403_1 - L060403_7, 2024/02

Spontaneous Hall conductivity has recently been reported in the triangular lattice antiferromagnet Co$$_{1/3}$$TaS$$_{2}$$ under a zero magnetic field. This phenomenon originates from the distinctive noncoplanar triple-$$mathbf{Q}$$ magnetic ground state, possessing uniform real-space Berry curvature characterized by scalar spin chirality. We investigated the physical properties of Co$$_{1/3}$$TaS$$_{2}$$ by judiciously controlling the composition, revealing a drastic change in its bulk properties, even by slight variations in cobalt composition, despite the same crystal structure. For $$0.299 le x le 0.325$$, Co$$_{x}$$TaS$$_{2}$$ keeps all the characteristics of the ground state consistent with the previous studies --- two antiferromagnetic phase transitions at $$T_mathrm{N1}$$ and $$T_mathrm{N2}$$ ($$< T_mathrm{N1}$$), a large spontaneous Hall conductivity [$$sigma_{xy}(mathbf{H} = 0)$$], and a weak ferromagnetic moment along the $$c$$ axis. However, samples with $$x ge 0.330$$ exhibit distinct bulk properties, including the absence of both $$sigma_{xy}(mathbf{H} = 0)$$ and the weak ferromagnetic moment. Our neutron diffraction data reveal that Co$$_{x}$$TaS$$_{2}$$ with $$x ge 0.330$$ develops coplanar helical magnetic order with $$mathbf{q}_mathrm{m1} =(1/3, 0, 0)$$. This is entirely different from what has been seen in $$x le 0.325$$, explaining the observed composition dependence.

論文

Quantum critical behavior of the hyperkagome magnet Mn$$_3$$CoSi

山内 宏樹; Sari, D. P.*; 安井 幸夫*; 坂倉 輝俊*; 木村 宏之*; 中尾 朗子*; 大原 高志; 本田 孝志*; 樹神 克明; 井川 直樹; et al.

Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02

$$beta$$-Mn-type family alloys Mn$$_3$$$$TX$$ have three-dimensional antiferromagnetic (AFM) corner-shared triangular network. The antiferromagnet Mn$$_3$$RhSi shows magnetic short-range order (SRO) over a wide temperature range of approximately 500 K above the N$'{e}$el temperature $$T_{rm N}$$ = 190 K. Mn$$_3$$CoSi has the smallest lattice parameter and the lowest $$T_{rm N}$$ in the family compounds. The quantum critical point (QCP) from AFM to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 $AA. Although $T_N$$ of Mn$$_3$$CoSi is only 140 K, quantum critical behavior is observed in Mn$$_3$$CoSi as the enhancement of the electronic specific heat coefficient $$gamma$$. We study how the magnetic SRO appears in Mn$$_3$$CoSi by using neutron scattering, $$mu$$SR, and physical property measurements. The experimental results show that the neutron scattering intensity of the magnetic SRO does not change much regardless of the suppressed magnetic moment in the long-range magnetic ordered state compared to those of Mn$$_3$$RhSi. The initial asymmetry drop ratio of $$mu$$SR above $$T_{rm N}$$ becomes small, and the magnetic SRO temperature $$T_{SRO}$$ is suppressed to 240 K. The results suggest that the Mn$$_3$$CoSi is close to the QCP in the Mn$$_3$$$$TX$$ system.

論文

Anisotropic electrical conductivity changes in FeTiO$$_3$$ structure transition under high pressure

山中 高光*; 中本 有紀*; 坂田 雅文*; 清水 克哉*; 服部 高典

Physics and Chemistry of Minerals, 51(1), p.4_1 - 4_10, 2024/02

FeTiO$$_3$$イルメナイトの中性子及び放射光X線回折と電気伝導度測定を高圧下で行った。イルメナイトの構造は28GPaまで保持された。構造解析の結果、8GPa以下ではFeO$$_6$$は圧縮され、TiO$$_6$$はほとんど圧縮されないことが分かった。抵抗率は、金属イオン対の中で原子間距離が最も短いFe-Ti方向で最も小さかった。c軸に垂直な方向の抵抗率は圧力とともに単調減少するが、c軸に沿った抵抗率は圧力とともに山なりとなった。最大エントロピー解析の結果、Fe$$^{2+}$$(3$$d^6$$)の電子配置はTi$$^{4+}$$(3$$d^0$$)よりも圧縮下で大きく変化することがわかった。異方的な電気伝導度とFe-Ti原子間距離の非一様な圧縮は、Feイオンの高スピン状態から中間スピン状態へのスピン転移によって説明できるかもしれない。

報告書

水銀ターゲット容器内壁のキャビテーション損傷観察に関する技術資料,2; キャビテーション損傷深さの測定

直江 崇; 涌井 隆; 木下 秀孝; 粉川 広行; 勅使河原 誠; 羽賀 勝洋

JAEA-Technology 2023-022, 81 Pages, 2024/01

JAEA-Technology-2023-022.pdf:9.87MB

大強度陽子加速器研究施設(Japan Proton Accelerator Research Complex, J-PARC)の物質・生命科学実験施設に設置されている核破砕パルス中性子源水銀ターゲットでは、高エネルギーのパルス陽子ビーム入射時に、核破砕反応による中性子の発生と同時に水銀の急激な熱膨張によって、圧力波が発生する。この圧力波は、水銀中を伝ぱする過程で負圧によるキャビテーションを誘発する。水銀を充填するステンレス鋼製の水銀ターゲット容器の内壁近傍でキャビテーションが崩壊することによって、内壁表面には激しい壊食損傷が形成される。水銀ターゲット容器は、陽子ビームが入射することによって先端部分の内部発熱に起因する熱応力を低減するために、先端部を厚さ3mmの薄肉構造としている。陽子ビーム強度の増加に伴って、キャビテーションによる攻撃性は増加するため、壊食損傷がターゲット容器の疲労破壊や水銀の漏洩につながる。したがって、設計出力である1MWでの長期的な安定運転を実現するために損傷の低減化が求められている。キャビテーションによる容器壁面の壊食損傷を低減することを目的として、圧力波を低減するための水銀中への微小気泡注入や、ターゲット容器先端部の2重壁構造化などの対策を施している。損傷低減化策の効果の確認や、ビーム出力と壊食痕による損傷深さの相関を評価し、今後の運転条件を検討するために、使用済みのターゲット容器の先端部から試験片を切出し、損傷の観察を実施している。これまでに、内壁に形成されたキャビテーションによる損傷形態の観察と壊食痕による損傷の深さを測定することで、運転条件との相関について検討を実施し、気泡注入によって著しい損傷低減効果が発現されること、2重壁構造によって、先端部分の損傷形成がビーム出力に依存せず抑制できることを確認した。これらの成果によって、施設の設計目標である1MWの安定運転を実施可能な見通しを得た。本報では、これまでに開発、適用した実機水銀ターゲット容器内壁の損傷観察の手法、測定結果及び運転条件との相関についてこれまでに得られた成果をまとめる。

論文

Martensitic transformation behavior of Fe-Ni-C alloys monitored by ${it in-situ}$ neutron diffraction during cryogenic cooling

山下 享介*; Harjo, S.; 川崎 卓郎; 諸岡 聡; Gong, W.; 藤井 英俊*; 友田 陽*

ISIJ International, 64(2), p.192 - 201, 2024/01

${it In situ}$ neutron diffraction measurements were performed on Fe-33Ni-0.004C alloy (33Ni alloy) and Fe-27Ni-0.5C alloy (27Ni-0.5C alloy) during cooling from room temperature to the cryogenic temperature (4 K) to evaluate changes in the lattice constants of austenite and martensite, and changes in the tetragonality of martensite due to thermally induced martensitic transformation. As the martensitic transformation progressed, the lattice constants of austenite in both alloys deviated to smaller values than those predicted considering the thermal shrinkage, accompanied by an increase in the full width at half maximum of austenite. The fresh martensite formed in both alloys had a body-centered tetragonal (BCT) structure, regardless of the carbon content. The tetragonality of martensite decreased with progressive martensitic transformation during cooling in the 33Ni alloy, but was almost constant in the 27Ni-0.5C alloy. This suggests that carbon is necessary to maintain the tetragonality of martensite during cooling. The tetragonality of martensite in the 27Ni-0.5C alloy decreased during room temperature aging because of carbon mobility.

論文

Probing deformation behavior of a refractory high-entropy alloy using ${it in situ}$ 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

The grain orientation-dependent lattice strain evolution of a (TiZrHfNb)$$_{98}$$$$N_2$$ refractory high-entropy alloy (HEA) during tensile loading has been investigated using ${it in situ}$ neutron diffraction. The equivalent strain-hardening rate of each of the primary $$<hkl>$$-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

Microscopic origin of the spin-reorientation transition in the kagome topological magnet TbMn$$_{6}$$Sn$$_{6}$$

Huang, Z.*; Wang, W.*; Ye, H.*; Bao, S.*; Shangguan, Y.*; Liao, J.*; Cao, S.*; 梶本 亮一; 池内 和彦*; Deng, G.*; et al.

Physical Review B, 109(1), p.014434_1 - 014434_9, 2024/01

TbMn$$_{6}$$Sn$$_{6}$$ is a correlated topological magnet with a Mn-based kagome lattice, in which a Chern gap opens at the Dirac point at low temperatures. The magnetic moment direction of the ferrimagnetic order changes from in the kagome plane to the out-of-plane upon cooling, which is essential for generating the Chern gap, but the underlying mechanism for the spin reorientation remains elusive. Here, we investigate the spin-reorientation transition in TbMn$$_{6}$$Sn$$_{6}$$ using neutron scattering. We provide direct evidence for the spin-reorientation transition and unveil the coexistence of two Tb modes at 200 K. To account for these results, we put forward a model based on SU(N) spin-wave theory, in which there is a temperature evolution of the ground state Tb $$4f$$ orbitals, driven by the crystalline electric field, single-ion anisotropy, and exchange interactions between Tb and Mn ions. Our findings shed light on the complex magnetism of TbMn$$_{6}$$Sn$$_{6}$$, despite its relatively simple ground state magnetic structure, and provide insights into the mechanisms for tuning magnetic topological materials.

論文

Magnetic boson peak in classical spin glasses

古府 麻衣子; 河村 聖子; 村井 直樹; 石井 梨恵子*; 平井 大悟郎*; 有馬 寛*; 舟越 賢一*

Physical Review Research (Internet), 6(1), p.013006_1 - 013006_9, 2024/01

We revisited spin dynamics in archetypical classical spin glass systems, such as Cu$$_{1-x}$$Mn$$_{x}$$ ($$x = 0.017$$, 0.034, and 0.067) dilute alloys and iron aluminosilicate glass using a modern neutron scattering spectrometer with high neutron flux. The former is crystalline, and the latter is amorphous, where their spin glass state is well separated from magnetically ordered phases. Bose-scaled localized magnetic excitations were observed in both compounds below the spin-freezing temperature ($$T_{rm f}$$). The spectrum exhibits a maximum at low energy and a broad tail on the high-energy side. The excitation energy tends to be higher for the material with a higher $$T_{rm f}$$. Above the $$T_{rm f}$$, the spectrum considerably changes with temperature, thereby indicating the emergence of the magnetic relaxation process. The magnetic excitation in the spin glass state has much in common with the boson peak in structural glasses. We consider that the Bose-scaled broad excitation peak is an elementary excitation inherent in disordered systems.

論文

Principal preferred orientation evaluation of steel materials using time-of-flight neutron diffraction

徐 平光; Zhang, S.-Y.*; Harjo, S.; Vogel, S. C.*; 友田 陽*

Quantum Beam Science (Internet), 8(1), p.7_1 - 7_13, 2024/01

Comprehensive information about the ${it in situ}$ microstructure and crystal structure evolution during the preparation/production processes of various materials is in great demand in order to precisely control the microstructure morphology and the preferred orientation characteristics for the excellent strength-ductility-toughness balance of advanced engineering materials. ${it In situ}$ isothermal annealing experiments of cold rolled 17Ni-0.2C (mass %) martensitic steel sheets were carried out by using the TAKUMI and ENGIN-X time-of-flight neutron diffractometers, respectively. The inverse pole figures based on full-profile refinement were extracted to roughly evaluate the preferred orientation features along three principal sample directions of investigated steel sheets using the General Structure Analysis System (GSAS) software with built-in generalized spherical harmonic functions. The consistent rolling direction (RD) inverse pole figures from TAKUMI and ENGIN-X have confirmed that the time-of-flight neutron diffraction has high repeatability and statistical reliability, revealing that the principal preferred orientation evaluation of steel materials is available through 90$$^{circ}$$ TD $$rightarrow$$ ND (transverse direction $$rightarrow$$ normal direction) rotation of the investigated specimen on the sample stage during two neutron diffraction experiments. Moreover, these RD, TD and ND inverse pole figures before and after in situ experiments were compared with the corresponding inverse pole figures recalculated respectively from the MUSASI-L complete pole figure measurement and the HIPPO in situ microstructure evaluation. The similar orientation distribution characteristics suggested that the principal preferred orientation evaluation method can be applied to in situ microstructure evolution of bulk orthorhombic materials and spatially resolved principal preferred orientation mappings of large engineering structure parts.

論文

Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis

二宮 和彦*; 久保 謙哉*; 稲垣 誠*; 吉田 剛*; Chiu, I.-H.; 工藤 拓人*; 浅利 駿介*; 千徳 佐和子*; 竹下 聡史*; 下村 浩一郎*; et al.

Scientific Reports (Internet), 14, p.1797_1 - 1797_8, 2024/01

鋼の特性を決める上で重要な鋼中のC量は、鋼の生産技術に大きく左右される。このため、ミュオンを使って鋼のC含有量を非破壊で測定する新しい方法を提案する。この方法は、生産中の鋼の品質管理だけでなく、貴重な鋼製考古学的遺物の分析にも使えるかもしれない。負の電荷を持つミュオンは原子系を形成し、最終的には核に吸収されるか電子に崩壊する。ミュオンの寿命は、Fe原子かC原子に捕らわれるかによってかなり違い、ミュオン停止位置での元素含有量をミュオン寿命測定で特定できる。C/Feのミュオン捕獲確率とCの元素含有量の関係は直線的で、ミュオン寿命測定で鋼のC含有量を定量的に決められる。さらに、ミュオンの入射エネルギーを調整して、0.5mm厚の3種類の鋼板からなる積層サンプルの各層でミュオンを停止させ、0.20-1.03wt%の範囲でC含有量を深さ選択的に、サンプルを壊さずに決定することに成功した。

論文

Recrystallization of bulk nanostructured magnesium alloy AZ31 after severe plastic deformation; An in situ diffraction study

Liss, K.-D.*; Han, J.-K.*; Blankenburg, M.*; Lienert, U.*; Harjo, S.; 川崎 卓郎; 徐 平光; 行武 栄太郎*; Kawasaki, M.*

Journal of Materials Science, 23 Pages, 2024/00

The magnesium alloy AZ31, which has undergone high-pressure torsion processing, was subjected to in situ annealing micro-beam synchrotron high-energy X-ray diffraction and compared to the as-received rolled sheet material that was investigated through in situ neutron diffraction. While the latter only exhibits thermal expansion and minor recovery, the nanostructured specimen displays a complex evolution, including recovery, strong recrystallization, phase transformations, and various regimes of grain growth. Nanometer-scale grain sizes, determined using Williamson-Hall analysis, exhibit seamless growth, aligning with the transition to larger grains, as assessed through the occupancy of single grain reflections on the diffraction rings. The study uncovers strain anomalies resulting from thermal expansion, segregation of Al atoms, and the kinetics of vacancy creation and annihilation. Notably, a substantial number of excess vacancies were generated through high-pressure torsion, and maintained for driving the recrystallization and forming highly activated volumes for diffusion and phase precipitation during heating. The unsystematic scatter observed in the Williamson-Hall plot indicates high dislocation densities following severe plastic deformation, which significantly decreases during recrystallization. Subsequently, dislocations reappear during grain growth, likely in response to torque gradients in larger grains. It is worth noting that the characteristics of unsystematic scatter differ for dislocations created at high and low temperatures, underscoring the strong temperature dependence of slip system activation.

報告書

MLFデータ処理環境"空蝉"インストールマニュアル

稲村 泰弘

JAEA-Testing 2023-002, 80 Pages, 2023/12

JAEA-Testing-2023-002.pdf:2.43MB

空蝉とは、J-PARCの物質・生命科学実験施設(MLF)において実施される中性子散乱実験にて得られたデータ処理に使用されるソフトウェア群の一つである。MLFの多くの装置(ビームライン)では、測定されたデータから条件に応じて抽出し、強度の規格化、装置機器依存の強度補正、単位変換などを行い、物理量へと変換し可視化する必要がある。空蝉はこの一連の処理を効率的に行うために開発されたソフトウェア群である。空蝉は主にデータの抽出機能(ヒストグラム化)や各種補正機能、それらを効率よく実行するためのグラフィカルインターフェースを持つソフトウェア、さらには処理されたデータを可視化するプロッタアプリケーションなどから構成されている。既にMLFの多数の装置において解析作業の要として動作している。本書は、MLFの中性子散乱装置を運用する装置担当者やユーザーが空蝉を利用したデータ処理を自分自身の計算機環境にて実施する際に、その環境構築やインストール作業を容易に実施できるよう、オペレーションシステムごとに具体的な手順を記述したマニュアルである。なお、WindowsやmacOSといった一般向けオペレーションシステムであれば、通常のアプリケーションを扱う程度の知識があれば本書を利用してインストールが可能である。

論文

Chiral Dirac fermion in a collinear antiferromagnet

Zhang, A.*; Deng, K.*; Sheng, J.*; Liu, P.*; Kumar, S.*; 島田 賢也*; Jiang, Z.*; Liu, Z.*; Shen, D.*; Li, J.*; et al.

Chinese Physics Letters, 40(12), p.126101_1 - 126101_8, 2023/12

In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, itis predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral "Dirac-like" fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Here, by combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions.

論文

Measurements of neutron total and capture cross sections of $$^{139}$$La and evaluation of resonance parameters

遠藤 駿典; 河村 しほり*; 奥平 琢也*; 吉川 大幹*; Rovira Leveroni, G.; 木村 敦; 中村 詔司; 岩本 修; 岩本 信之

European Physical Journal A, 59(12), p.288_1 - 288_12, 2023/12

ランタン(La)-139の断面積と共鳴パラメータは、原子力分野への応用や基礎核物理の研究にとって重要である。本論文では、大強度陽子加速器施設(J-PARC)のANNRIにてLaの中性子全断面積と捕獲断面積を測定した。Negative共鳴を含む4つの共鳴の共鳴パラメータを、共鳴解析コードREFITを用いて求めた。その結果いくつかの共鳴パラメータにおいて、評価済み核データライブラリとの不一致が見られた。さらに全断面積を再現するために、スピン依存する散乱半径もフィットした。得られた散乱半径は、評価済み核データライブラリで記録されたものよりも大きいことがわかった。

論文

Microphase separation of cationic homopolymers bearing alkyl ammonium salts into sub-4 nm lamellar materials with water intercalation channels

筋田 涼太*; 今井 彩帆里*; 大内 誠*; 青木 裕之; 寺島 崇矢*

Macromolecules, 56(23), p.9738 - 9749, 2023/12

Constructing ordered ionic nanostructures into bulk polymers and thin films is an important technique to create functional materials, such as polyelectrolytes and proton- and ion-conducting materials, for various applications. Herein, we report microphase separation of cationic homopolymers bearing alkyl ammonium bromides to create sub-4 nm lamellar materials, where an ionic phase is alternatingly layered with a hydrophobic alkyl phase and serves as a channel for water intercalation. We prepared cationic homopolymers with linear or branched alkyl pendants (octyl or 2-ethylhexyl group: C8-eicosyl or 2-octyldodecyl group: C20) via the free radical polymerization of 2-(dimethylamino)ethyl acrylate (DMAEA), followed by the quaternization of the polyDMAEA with corresponding alkyl bromides. The homopolymers carrying linear hexadecyl, octadecyl, and eicosyl groups were crystalline at room temperature, whereas the others were amorphous. The homopolymers bearing linear alkyl pendants longer than the decyl group or branched alkyl pendants larger than the 2-butyloctyl group formed lamellar structures by the self-assembly of the side chains. The domain spacing can be controlled between 2.5 and 3.7 nm by tuning the pendant structures and are smaller than that formed by the corresponding random copolymers. A cationic homopolymer bearing crystalline octadecyl groups maintained lamellar structures up to $$sim$$210 $$^circ$$C far beyond the melting temperature ($$sim$$50 $$^circ$$C). The cationic homopolymer further formed a multilayered lamellar thin film on a silicon substrate, in which the cationic layers absorbed water under humid conditions and reversibly released the water therefrom in a N$$_2$$ gas atmosphere.

2761 件中 1件目~20件目を表示