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FCC hierarchical martensite transformation under dynamic impact in FeMnAlNiTi alloyLi, C.*; Fang, W.*; Yu, H. Y.*; Peng, T.*; Yao, Z. T.*; Liu, W. G.*; Zhang, X.*; 徐 平光; Yin, F.*
Materials Science & Engineering A, 892, p.146096_1 - 146096_11, 2024/02
被引用回数：0 パーセンタイル：0.02(Nanoscience & Nanotechnology)The quasi-static superelastic responses and hierarchical martensite transformation from body-centered cubic (BCC) to face-centered cubic (FCC) under dynamic impact in Fe
Mn
Al
Ni
Ti
alloys were investigated. Polycrystalline and oligocrystalline alloys were produced through solution heat treatment and cyclic heat treatment processes, respectively. The results show the volume fraction of residual martensite for oligocrystalline alloys is lower, which exhibits better superelastic responses compared with polycrystalline alloys. Dynamic impact tests indicate that, despite the weakening of the grain boundary strengthening effect, the ultimate strength of the oligocrystalline alloys closely matches that of the polycrystalline alloys under dynamic impact. The martensite transformation of the FeMnAlNiTi alloy is characterized as hierarchical under dynamic impact, and increasing strain rates and grain sizes can enhance the BCC FCC martensite transformation, resulting in higher martensite phase fractions for oligocrystalline alloys. The increase in ultimate strength is attributed to the dynamic Hall-Petch effect introduced by more martensite phase interfaces under dynamic impact.
廣田 夕貴*; 富永 大輝*; 川端 隆*; 川北 至信; 松尾 康光*
Bioengineering (Internet), 10(5), p.622_1 - 622_17, 2023/05
被引用回数：0 パーセンタイル：0.01(Biotechnology & Applied Microbiology)Recently, it was reported that chitin and chitosan exhibited high-proton conductivity and function as an electrolyte in fuel cells. In particular, it is noteworthy that proton conductivity in the hydrated chitin becomes 30 times higher than that in the hydrated chitosan. Since higher proton conductivity is necessary for the fuel cell electrolyte, it is significantly important to clarify the key factor for the realization of higher proton conduction from a microscopic viewpoint for the future development of fuel cells. Therefore, we have measured proton dynamics in the hydrated chitin using quasi-elastic neutron scattering (QENS) from the microscopic viewpoint and compared the proton conduction mechanism between hydrated chitin and chitosan. QENS results exhibited that a part of hydrogen atoms and hydration water in chitin are mobile even at 238 K, and the mobile hydrogen atoms and their diffusion increase with increasing temperature. It was found that the diffusion constant of mobile protons is two times larger and that the residence time is two times in chitin faster than that in chitosan. In addition, it is revealed from the experimental results that the transition process of dissociable hydrogen atoms between chitin and chitosan is different. To realize proton conduction in the hydrated chitosan, the hydrogen atoms of the hydronium ions (H
O
) should be transferred to another hydration water. By contrast, in hydrated chitin, the hydrogen atoms can transfer directly to the proton acceptors of neighboring chitin. It is deduced that higher proton conductivity in the hydrated chitin compared with that in the hydrated chitosan is yielded by the difference of diffusion constant and the residence time by hydrogen-atom dynamics and the location and number of proton acceptors.
橋本 俊輔*; 山口 聡*; 原田 雅史*; 中島 健次; 菊地 龍弥*; 大石 一城*
Journal of Colloid and Interface Science, 638, p.475 - 486, 2023/05
被引用回数：2 パーセンタイル：60.61(Chemistry, Physical)最近、粒子分率から計算される理論的に予測された値と比較して、ベース液体と分散された固体ナノ粒子で構成されるナノ流体の熱伝導率の異常な改善が報告されている。一般に、気体と液体の熱伝導率の値は、並進運動中の分子の平均自由行程によって支配される。ここでは、ナノ粒子の周りの液体分子の振動挙動がこれらの熱伝導率の増加に寄与している可能性を示す確かな証拠を提示する。
dynamics in the H conductors LaH
O
玉造 博夢; 福井 慧賀*; 飯村 壮史*; 本田 孝志*; 多田 朋史*; 村上 洋一*; 山浦 淳一*; 倉本 義夫*; 佐賀山 基*; 山田 武*; et al.
Physical Review B, 107(18), p.184114_1 - 184114_8, 2023/05
被引用回数：0 パーセンタイル：0(Materials Science, Multidisciplinary)Using an incoherent quasi-elastic neutron scattering (QENS) technique, we investigate H dynamics in a series of oxyhydrides LaHO that exhibit characteristic high H conductivity. In the end member LaH (
= 0), two kinds of H dynamics are identified: the jump diffusion and the localized motion. The jump length in the jump diffusion mode increases with increasing 
. The localized motion is identified as a jump between the two inequivalent sites. These dynamics are corroborated by our molecular dynamical simulations. Our QENS data suggest that similar H dynamics occurs also in oxyhydrides LaHO ( 
0), whose H concentration dependence is consistent with the previous measurement of ionic conductivity. We also discuss the possibility that LaHO is an example of H ion conductors governed by the concerted migration mechanism. The identified H dynamics is a key to understanding the anomalous hydrogen concentration dependence of the diffusion coefficient in lanthanum hydrides, which has been a longstanding mystery in this compound.
H
O藤原 理賀; 萩原 雅人; 森田 克洋*; 村井 直樹; 幸田 章宏*; 岡部 博孝*; 満田 節生*
Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02
被引用回数：0 パーセンタイル：0(Materials Science, Multidisciplinary)
= 1/2ハイゼンベルグ直線鎖反強磁性体は、最も単純なスピンモデルであるが、様々な量子多体現象のプラットフォームを提供する。この論文では、準一次元反強磁性体KCuPOHOの磁性を報告した。
= 11.7(1) Kにおいて、格子整合な長距離反強磁性秩序が形成され、その磁気モーメントの大きさは0.31(1) 
である事がわかった。また鎖内相互作用
と鎖間相互作用
の大きさはそれぞれ172Kと4.25(4) Kと見積もられ、/の比は0.0247(3)である。中性子非弾性散乱実験により、より高温では、一次元ハイゼンベルグ量子スピン鎖の特徴である連続体励起スペクトルが観測され、より低温では、分散励起にスピンギャップが観測された。これらの結果は、弱く結合した = 1/2ハイゼンベルグスピン鎖系で観測される性質と一致する。
中島 健次; 菊地 龍弥*; 河村 聖子; 神原 理*
EPJ Web of Conferences, 272, p.02012_1 - 02012_8, 2022/11
パルス源の冷中性子チョッパー分光計であるAMATEASで、単一測定条件での時間枠を増やす試みのいくつかを紹介する。方法の1つは、飛行時間図で介在する軌道を許可することにより、
で選択可能な使用可能な幅を増やすことができるということである。われわれの経験に基づいて、パルス源でのチョッパー分光計でのパルス繰り返し周波数増倍に基づく多色測定の条件について説明する。広帯域多色測定の最適化と一般化された定式化された条件が提案される。既存の分光計および最適化されたチョッパー分光計の基準設計へのわれわれのアイデアの適用についても説明し、パルス整形チョッパーを変更することによって効率を改善するさらなる可能性を示唆する。
Xu, X.*; 大平 拓実*; Xu, S.*; 平田 研二*; 大森 俊洋*; 植木 洸輔*; 上田 恭介*; 成島 尚之*; 長迫 実*; 貝沼 亮介*; et al.
Advanced Materials & Processes, 180(7), p.35 - 37, 2022/10
Metallic biomaterials are widely used to replace or support failing hard tissues due to excellent mechanical properties and high wear resistance, with demand increasing as the global population continues to age. It is widely accepted that successful metallic biomaterials should have good biocompatibility, high corrosion resistance, and strong wear resistance. In addition, a low Young's modulus similar to human bone is now recognized as another important factor, in order to avoid bone atrophy due to the stress shielding effect. While the Young's modulus of stainless steels and conventional fcc CoCr alloys is as high as 190-240 GPa, for 
-type Ti-base alloys it is generally in the range of 50-80 GPa. Young's modulus values are as low as 35 GPa for Ti-Nb-Ta-Zr, close to that of human bone at approximately 10-30 GPa. However, Ti-base alloys come with the compromise of low wear resistance. In fact, alloys that feature a low Young's modulus along with high wear resistance have been difficult to realize. This article explores the recently developed bcc CoCr-base alloy Co-Cr-Al-Si as a potential solution to these issues, i.e., the difficulty in combining a low Young's modulus with high wear resistance, and the challenge of realizing large superelastic strains.
廣田 夕貴*; 富永 大輝*; 川端 隆*; 川北 至信; 松尾 康光*
Bioengineering (Internet), 9(10), p.599_1 - 599_17, 2022/10
被引用回数：2 パーセンタイル：32.07(Biotechnology & Applied Microbiology)Chitosan, which is an environmentally friendly and highly bio-producible material, is a potential proton-conducting electrolyte for use in fuel cells. Thus, to microscopically elucidate proton transport in hydrated chitosan, we employed the quasi-elastic neutron scattering (QENS) technique. QENS analysis showed that the hydration water, which was mobile even at 238 K, moved significantly more slowly than the bulk water, in addition to exhibiting jump diffusion. Furthermore, upon increasing the temperature from 238 to 283 K, the diffusion constant of water changed increased from 
to 
cm
/s. It was also found that a portion of the hydrogen atoms in chitosan undergo a jump-diffusion motion similar to that of the hydrogen present in water. Moreover, QENS analysis revealed that the activation energy for the jump-diffusion of hydrogen in chitosan and in the hydration water was 0.30 eV, which is close to the value of 0.38 eV obtained from the temperature-dependent proton conductivity results. Overall, it was deduced that a portion of the hydrogen atoms in chitosan dissociate and protonate the interacting hydration water, resulting in the chitosan exhibiting proton conductivity.
and TiH
up to 21 GPa by incoherent inelastic neutron scattering服部 高典; 中村 充孝; 飯田 一樹*; 町田 晃彦*; 佐野 亜沙美; 町田 真一*; 有馬 寛*; 大下 英敏*; 本田 孝志*; 池田 一貴*; et al.
Physical Review B, 106(13), p.134309_1 - 134309_9, 2022/10
被引用回数：0 パーセンタイル：0(Materials Science, Multidisciplinary)量子調和振動子(QHO)で近似できる蛍石型のZrHとTiHの水素の振動励起を非弾性非干渉性中性子散乱によって21GPaおよび4GPaまで調べた。第一励起の振動エネルギー
はそれぞれ(meV) = 141.4(2) + 1.02(2)
(GPa)および(meV) = 149.4(1) + 1.21(8)(GPa)で表され、圧力とともに上昇した。格子定数の圧力変化と組み合わせて得られた金属水素原子間距離(
)との関係は、(meV) = 1.62(9)
10
(
および(meV) = 1.47(21) 10 
(であった。これらのカーブの傾きは、様々な蛍石型の金属水素化物の常圧下のトレンドに比べ、急峻であった。から得られた水素波動関数の広がりは、格子間サイトよりも縮み易いことが分かった。高圧下における水素の波動関数の優先的な収縮や小さなにおけるの急峻な立ち上がりは金属原子のイオンコアが水素原子よりも堅いために水素原子が高圧下でより狭い領域に閉じ込められるために起こると考えられる。
大平 拓実*; Xu, S.*; 平田 研二*; Xu, X.*; 大森 俊洋*; 植木 洸輔*; 上田 恭介*; 成島 尚之*; 長迫 実*; Harjo, S.; et al.
Advanced Materials, 34(27), p.2202305_1 - 2202305_11, 2022/07
被引用回数：12 パーセンタイル：87.92(Chemistry, Multidisciplinary)The demand for biomaterials has been increasing along with the increase in the population of elderly people worldwide. The mechanical properties and high wear resistance of metallic biomaterials makes them well-suited for use as substitutes or as support for damaged hard tissues. However, unless these biomaterials also have a low Young's modulus similar to that of human bones, bone atrophy inevitably occurs. Because a low Young's modulus is typically associated with poor wear resistance, it is difficult to realize a low Young's modulus and high wear resistance simultaneously. Also, the superelastic property of shape memory alloys makes them suitable for biomedical applications, like vascular stents and guide wires. However, due to the low recoverable strain of conventional biocompatible shape memory alloys, the demand for a new alloy system is high. The novel body-center-cubic cobalt-chromium-based alloys in this paper provide a solution to both of these problems. We believe our novel alloys are promising candidates for biomedical applications.
Puebla, J.*; Hwang, Y.*; 前川 禎通*; 大谷 義近*
Applied Physics Letters, 120(22), p.220502_1 - 220502_9, 2022/05
被引用回数：20 パーセンタイル：93.77(Physics, Applied)Surface acoustic waves (SAWs) are elastic waves propagating on the surface of solids with the amplitude decaying into the solid. The well- established fabrication of compact SAW devices, together with well-defined resonance frequencies, places SAWs as an attractive route to manipulate the magnetization states in spintronics, all of which is made possible by the magnetostriction and magnetoelastic effects. Here, we review the basic characteristics of SAW devices and their interaction out-of-resonance and in-resonance with the magnetization in thin films. We describe our own recent results in this research field and closely related works and provide our perspectives moving forward.
Al
and Nd
Pd
Ge
目時 直人; 柴田 薫; 松浦 直人*; 北澤 英明*; 鈴木 博之*; 山内 宏樹; 萩原 雅人; Frontzek, M. D.*; 松田 雅昌*
Journal of the Physical Society of Japan, 91(5), p.054710_1 - 054710_6, 2022/05
被引用回数：0 パーセンタイル：0(Physics, Multidisciplinary)NdPdAlにおけるNdの超微細相互作用分裂を高分解能の中性子非弾性散乱によって研究した。Nd核の核スピン(
=7/2)と、
の軌道が主成分の
基底状態を示す4
電子との間の超微細相互作用によって、磁気秩序相において生じた超微細相互作用分裂に起因する中性子非弾性散乱ピークを、
= 
3
eVのエネルギーに観察した。低温では、Nd核スピンの低エネルギー状態の占拠確率が増加することによりNd核スピンが偏極し、反強磁性散乱ピーク強度に寄与するが、その際、中性子の非スピン反転過程の寄与が最も大きい。この現象の応用として反強磁性散乱ピーク強度の温度変化から、NdPdGeのNd磁気モーメント及び超微細相互作用分裂の大きさを見積もることに成功した。
古池 美彦*; Ouyang, D.*; 富永 大輝*; 松尾 龍人*; 向山 厚*; 川北 至信; 藤原 悟*; 秋山 修志*
Communications Physics (Internet), 5(1), p.75_1 - 75_12, 2022/04
被引用回数：4 パーセンタイル：65.23(Physics, Multidisciplinary)Circadian clock proteins often reveal temperature-compensatory responses that counteract temperature influences to keep their enzymatic activities constant over a physiological range of temperature. This temperature-compensating ability at the reaction level is likely crucial for circadian clock systems, to which the clock proteins are incorporated, to achieve the system-level temperature compensation of the oscillation frequency. Nevertheless, temperature compensation is yet a puzzling phenomenon, since side chains that make up the clock proteins fluctuate more frequently due to greater thermal energy at higher temperature. Here, we investigated temperature influences on the dynamics of KaiC, a temperature-compensated enzyme (ATPase) that hydrolyzes ATP into ADP in the cyanobacterial circadian clock system, using quasielastic neutron scattering. The frequency of picosecond to subnanosecond incoherent local motions in KaiC was accelerated by a factor of only 1.2 by increasing the temperature by 10
C. This temperature insensitivity of the local motions was not necessarily unique to KaiC, but confirmed also for a series of temperature-sensitive mutants of KaiC and proteins other than clock-related proteins. Rather, the dynamics associated with the temperature-compensatory nature of the reaction- and system-level was found in global diffusional motions, which was suggested to regulate the temperature dependence of ATPase activity and dephosphorylation process presumably through changes in the hexamer conformation of KaiC. The spatiotemporal scale at which cross-scale causality of the temperature sensitivity is established is finite, and extends down to picosecond to subnanosecond dynamics only in a very limited part of KaiC, not in its entire part.
Yang, J.*; Ren, W.*; Zhao, X.*; 菊地 龍弥*; Miao, P.*; 中島 健次; Li, B.*; Zhang, Z.*
Journal of Materials Science & Technology, 99, p.55 - 60, 2022/02
被引用回数：6 パーセンタイル：39.91(Materials Science, Multidisciplinary)物性測定と中性子散乱を組み合わせることにより、面心立方高エントロピー合金CrMnFeCoNiの磁気および熱輸送特性を調べた。DCおよびAC帯磁率は、温度領域全体で反強磁性および強磁性相互作用が共存する常磁性挙動を示し、それぞれ、常磁性から反強磁性への遷移、反強磁性から強磁性への遷移、およびスピン凍結に対応して、約80, 50、および20Kで3つの異常が見られる。電気伝導率と熱伝導率はNiに比べて大幅に低下しており、格子熱伝導率の温度依存性はガラスのようなプラトーを示す。非弾性中性子散乱測定は弱い非調和性を示唆し、熱輸送は欠陥散乱によって支配されると思われる。
船戸 匠*; 松尾 衛
Physical Review Letters, 128(7), p.077201_1 - 077201_6, 2022/02
被引用回数：3 パーセンタイル：56.47(Physics, Multidisciplinary)The spin-motive force (SMF) in a simple ferromagnetic monolayer caused by a surface acoustic wave is studied theoretically via spin-vorticity coupling (SVC). The SMF has two mechanisms. The first is the SVC-driven SMF, which produces the first harmonic electromotive force, and the second is the interplay between the SVC and the magnetoelastic coupling, which produces the dc and second harmonic electromotive forces. We show that these electric voltages induced by a Rayleigh-type surface acoustic wave can be detected in polycrystalline nickel. No sophisticated device structures, noncollinear magnetic structures, or strong spin-orbit materials are used in our approach. Consequently, it is intended to broaden the spectrum of SMF applications considerably.
服部 高典; 河村 聖子; 川崎 卓郎
High Pressure Research, 42(2), p.226 - 235, 2022/00
被引用回数：0 パーセンタイル：0(Physics, Multidisciplinary)約1GPaまでの準弾性中性子散乱実験(QENS)のためのハイブリッドピストンシリンダーセルを開発した。このセルは、高張力鋼(SNCM439)のライナーとAl合金(NA700)のジャケットで構成される押し嵌めシリンダーからなる。性能試験の結果、0.8GPaの圧力に耐えることができ、3.14meV(波長5.10
)の中性子透過率が従来のCuBeモノブロックシリンダーの4.4倍であることが確認された。多重散乱を抑制するために考案したサンプルアセンブリと組み合わせることで、0.8GPaまでの水の高品質なQENSスペクトルを得ることができた。本研究は、ハイブリッドシリンダーが最大発生圧力を増大させるためだけでなく、発生圧力や信号強度を実験の目的に応じて調整するのに有効であることを示している。
富永 大輝*; 佐原 雅恵*; 川北 至信; 中川 洋; 山田 武*
Journal of Applied Crystallography, 54(6), p.1631 - 1640, 2021/12
被引用回数：4 パーセンタイル：54.54(Chemistry, Multidisciplinary)For quasi-elastic neutron scattering (QENS) studies, sample cells made of pure or alloyed aluminum are frequently employed. Although the Al surface is protected by a passivating film, this film is not robust. Therefore, when the sample is an aqueous solution, chemical interactions between the Al surface and sample, promoted by corrosive entities such as chloride ions and certain conditions of pH, can compromise the integrity of the cell and interfere with the experiment. In this study, the corrosion susceptibilities of Al and its alloys were investigated by subjecting them to various treatments; the results were compared with those of other candidate materials with low chemical reactivity. This work showed that alloys with higher Al content and boehmite-coated surfaces are resistant to corrosion. In particular, for Al, the resistance is due to a reduction in the contact area achieved by reducing the surface roughness. QENS measurements of empty sample cells made of these materials revealed two results: (1) the profile of the cell fabricated with a copper-free Al alloy showed a minor dependence on the scattering vector magnitude 
and (2) reducing the real surface area of Al effectively suppresses its scattering intensity, while boehmite coating strengthens the scattering. Cells fabricated with Mo, Nb and single-crystal sapphire can be used as alternatives to Al because of their low scattering intensity and reduced dependence on .
Li
TiO (x = 0.13) studied by quasielastic neutron scattering松浦 直人*; 藤原 靖幸*; 森分 博紀*; 尾原 幸治*; 川北 至信
Physical Review B, 104(9), p.094305_1 - 094305_7, 2021/09
被引用回数：5 パーセンタイル：43.44(Materials Science, Multidisciplinary)Quasielastic neutron scattering (QENS) measurements combined with first principles based molecular dynamics calculations were conducted to study the dynamics of Li ions in a solid-state electrolyte LaLiTiO (LLTO) with 
. By using a large 
Li-enriched single crystal sample, a QENS signal was clearly observed along the three principal axes [110], [111], and [001] at a temperature () of 600 K. Wave vector dependence of the linewidth of the QENS signal along each direction was explained well using the Chudley-Elliot model for jumps between the A sites of the perovskite lattice through the bottleneck square, which was also supported by molecular dynamics calculations. The estimated self-diffusion coefficient of Li (
) in the ab plane was slightly larger than that along the c axis, suggesting quasi-isotropic diffusion, that is, the three-dimensional diffusion of Li ions. The decrease in with decreasing was reasonably explained by a thermal activation process with the activation energy determined from ionic-conductivity measurements. Furthermore, the estimated values of the self-diffusion coefficient are comparable to those in the sulfide-based Li ion conductor, Li
PS
, with 10 times larger ionic conductivity, which clarifies how to understand the Li conduction mechanism in LLTO and LiPS in a unified manner.
船戸 匠*; 松尾 衛
Physical Review B, 104(6), p.L060412_1 - L060412_5, 2021/08
被引用回数：3 パーセンタイル：26.56(Materials Science, Multidisciplinary)We theoretically study spin transport in two- or three-dimensional Rashba systems dynamically distorted by surface acoustic waves. The spin currents in the linear response to lattice distortion dynamics are calculated on the basis of a microscopic theory combined with local coordinate transformations. As a result, we find a mechanism of direct spin-current generation from lattice distortion not associated with a charge current or spin accumulation. Moreover, the in-plane helicity currents are generated by shear surface acoustic waves via the present mechanism. The generated helicity currents are not parallel to the vorticity of the lattice, and cannot be created with the conventional methods. Thus, our findings offer an alternative functionality of the conventional Rashba systems in the field of spintronics.
橋立 竜太; 加藤 章一; 鬼澤 高志; 若井 隆純; 笠原 直人*
Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 9 Pages, 2021/07
過大地震荷重下における構造物の破損メカニズムを明らかにすることは非常に重要である。一方で、実際の構造材料を使用した構造物試験は非常に難しく、費用もかかる。そのため、過度の地震荷重下での構造破損メカニズムをシミュレートするために、模擬材料として鉛合金を用いた試験技術を提案した。この研究では、鉛合金を使用して材料試験を実施し、模擬材料試験の有効性を検証した。さらに、一連の材料試験の結果に基づいて、鉛合金の非弾性構成方程式(最適疲労破損式と動的応力-ひずみ関係式)を作成した。提案した式を用いることで、有限要素解析等の非線形解析も実行可能にした。これらの結果から、模擬材料試験技術が、過大地震荷重下での構造物の破損メカニズム解明に有効な手法として提案することができた。
