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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
被引用回数：1 パーセンタイル：0(Physics, Multidisciplinary)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.
SnSe
Ren, Q.*; Gupta, M. K.*; Jin, M.*; Ding, J.*; Wu, J.*; Chen, Z.*; Lin, S.*; Fabelo, O.*; Rodriguez-Velamazan, J. A.*; 古府 麻衣子; et al.
Nature Materials, 22, p.999 - 1006, 2023/05
被引用回数：21 パーセンタイル：99.22(Chemistry, Physical)Ultralow thermal conductivity and fast ionic diffusion endow superionic materials with excellent performance both as thermoelectric converters and as solid-state electrolytes. Yet the correlation and interdependence between these two features remain unclear owing to a limited understanding of their complex atomic dynamics. Here we investigate ionic diffusion and lattice dynamics in argyrodite AgSnSe using synchrotron X-ray and neutron scattering techniques along with machine-learned molecular dynamics. We identify a critical interplay of the vibrational dynamics of mobile Ag and a host framework that controls the overdamping of low-energy Ag-dominated phonons into a quasi-elastic response, enabling superionicity. Concomitantly, the persistence of long-wavelength transverse acoustic phonons across the superionic transition challenges a proposed 'liquid-like thermal conduction' picture. Rather, a striking thermal broadening of low-energy phonons, starting even below 50 K, reveals extreme phonon anharmonicity and weak bonding as underlying features of the potential energy surface responsible for the ultralow thermal conductivity (
0.5 Wm
K) and fast diffusion. Our results provide fundamental insights into the complex atomic dynamics in superionic materials for energy conversion and storage.
中西 匠*; 堀 優太*; 重田 育照*; 佐藤 寛泰*; Wu, S.-Q.*; 鬼柳 亮嗣; 宗像 孝司*; 大原 高志; 佐藤 治*
Physical Chemistry Chemical Physics, 25(17), p.12394 - 12400, 2023/05
被引用回数：1 パーセンタイル：56.86(Chemistry, Physical)The application of single-crystal neutron diffraction (SCND) to observe proton-transfer phenomena in crystalline compounds exhibiting unusual protonation states or proton dynamics has garnered significant research interest in recent years. However, proton tautomerism, which results in different protonation states before and after proton transfer, has never been observed using the SCND technique. Thus, to observe the proton tautomerism phenomenon by SCND measurements, we developed an iron(II) complex that forms a large crystal and exhibits a proton-transfer-coupled spin transition (PCST). The presence of the two types of proton tautomers was determined by conventional analysis of the proton position by X-ray crystallography, infrared spectroscopy, and density functional theory calculations. Finally, our results confirmed that proton tautomerism was successfully observed for the first time using variable-temperature SCND measurements.
Ao, N.*; Zhang, H.*; Xu, H. H.*; Wu, S. C.*; Liu, D.*; 徐 平光; Su, Y. H.; Kang, Q. H.*; Kang, G. Z.*
Engineering Fracture Mechanics, 281, p.109166_1 - 109166_14, 2023/03
被引用回数：4 パーセンタイル：85.05(Mechanics)Considering the complex service environments that high-speed railway axles are subjected to, the fatigue crack growth (FCG) behavior of a structurally gradient axle steel with different pre-crack depths both in air and corrosive medium was investigated at a frequency of 5 Hz. The results indicated that in the high 
region, FCG rate was dramatically accelerated by corrosion, but the gap narrows as decreased. The accelerated corrosion FCG rate was a comprehensive result of the acceleration effect of the anodic dissolution, hydrogen-enhanced localized plasticity and the retardation effect of corrosion-induced crack-tip blunting. Despite the fact that the corrosion resistance gradually decreased as the pre-crack depth increased, the FCG rate in the corrosive medium gradually decreased. This was because fatigue loading played a more important role than corrosion in accelerating the corrosion FCG rate.
BaCo(PO
)Sheng, J.*; Wang, L.*; Candini, A.*; Jiang, W.*; Huang, L.*; Xi, B.*; Zhao, J.*; Ge, H.*; Zhao, N.*; Fu, Y.*; et al.
Proceedings of the National Academy of Sciences of the United States of America, 119(51), p.e2211193119_1 - e2211193119_9, 2022/12
被引用回数：3 パーセンタイル：28(Multidisciplinary Sciences)Although considerable progress has been made in the theoretical understanding of the low-dimensional frustrated quantum magnets, experimental realizations of a well-established scaling analysis are still scarce. This is particularly true for the two-dimensional antiferromagnetic triangular lattices. Owing to the small exchange strength, the newly discovered compound NaBaCo(PO) provides a rare opportunity for clarifying the quantum criticality in an ideal triangular lattice with quantum spin S=1/2. In addition to the establishment of the complete phase diagrams, the spin Hamiltonian with a negligible interplane interaction has been determined through the spin wave dispersion in the polarized state, which is consistent with the observation of a two-dimensional quantum critical point with the Bose-Einstein condensation of diluted free bosons.
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
被引用回数：49 パーセンタイル：98.33(Chemistry, Multidisciplinary)Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing HO 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
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 PtCo cores.
Wu, C.*; 田中 万也; 谷 幸則*; Bi, X.*; Liu, J.*; Yu, Q.*
Science of the Total Environment, 821, p.153265_1 - 153265_9, 2022/05
被引用回数：21 パーセンタイル：94.35(Environmental Sciences)異なる粒径のマイクロプラスチックを淡水性の真菌である
KR21-2株とともに培養し、マイクロプラスチック表面にバイオフィルムを形成させた。それらの物理化学的特性を調べた結果、バイオフィルムによる被覆により表面への重金属元素の吸着容量が高くなり、その程度はマイクロプラスチックの粒径に関係していることが明らかとなった。このことは、マイクロプラスチックがバイオフィルム形成を通じて環境中における重金属の重要なキャリアとなり得ることを示している。
Wang, Y.*; Jia, G.*; Cui, X.*; Zhao, X.*; Zhang, Q.*; Gu, L.*; Zheng, L.*; Li, L. H.*; Wu, Q.*; Singh, D. J.*; et al.
Chem, 7(2), p.436 - 449, 2021/02
被引用回数：194 パーセンタイル：99.8(Chemistry, Multidisciplinary)Nanozymes are promising alternatives to natural enzymes, but their use remains limited owing to poor specificity. Overcoming this is extremely challenging due to the intrinsic structural complexity of these systems. We report theoretical design and experimental realization of a series of heterogeneous molybdenum single-atom nanozymes (named Mo
-N
-C), wherein we find that the peroxidase-like specificity is well regulated by the coordination numbers of single Mo sites. The resulting Mo-N-C catalyst shows exclusive peroxidase-like behavior. It achieves this behavior via a homolytic pathway, whereas Mo-N-C and Mo-N-C catalysts have a different heterolytic pathway. The mechanism of this coordination-number-dependent enzymatic specificity is attributed to geometrical structure differences and orientation relationships of the frontier molecular orbitals.
Wu, Q.*; 肥山 詠美子*; Kim, H.-C.; Yakhshiev, U.*; Zong, H.*
Progress of Theoretical and Experimental Physics (Internet), 2018(12), p.123D01_1 - 123D01_11, 2018/12
被引用回数：0 パーセンタイル：0.01(Physics, Multidisciplinary)We investigate the mass spectra of ordinary heavy mesons, based on a nonrelativistic potential approach. The heavy-light quark potential contains the Coulomb-type potential arising from one-gluon exchange, the confining potential, and the instanton-induced nonperturbative local heavy-light quark potential. All parameters are theoretically constrained and fixed. We carefully examine the effects from the instanton vacuum. Within the present form of the local potential from the instanton vacuum, we conclude that the instanton effects are rather marginal on the charmed mesons.
Li, B.; Wang, H.*; 川北 至信; Zhang, Q.*; Feygenson, M.*; Yu, H. L.*; Wu, D.*; 尾原 幸治*; 菊地 龍弥*; 柴田 薫; et al.
Nature Materials, 17(3), p.226 - 230, 2018/03
被引用回数：121 パーセンタイル：96.83(Chemistry, Physical)As a generic property, all substances transfer heat through microscopic collisions of constituent particles. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here, we report liquid-like thermal conduction observed in the crystalline AgCrSe. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive, and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. These microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.
Li, B.; Luo, X. H.*; Wang, H.*; Ren, W. J.*; Yano, S.*; Wang, C.-W.*; Gardner, J. S.*; Liss, K.-D.*; Miao, P.*; Lee, S.-H.*; et al.
Physical Review B, 93(22), p.224405_1 - 224405_6, 2016/06
被引用回数：45 パーセンタイル：85.49(Materials Science, Multidisciplinary)Competition between ferromagnetic and antiferromagnetic phases on frustrated lattices in hexagonal Laves phase compound Hf
Ta
Fe is investigated by using neutron diffraction as a function of temperature and magnetic fields and density-functional-theory calculations. At 325 K, the compound orders into the 120
frustrated antiferromagnetic state with well-reduced magnetic moment and an in-plane lattice contraction simultaneously sets in. With further cooling down, however, the accumulated distortion in turn destabilizes this susceptible frustrated structure. The frustration is completely relieved at 255 K when the first-order transition to the ferromagnetic state takes place, where a colossal negative volumetric thermal expansion, 
/K, is obtained. Meanwhile, the antiferromagnetic state can be suppressed by few Tesla magnetic fields, which results in a colossal positive magnetostriction. Such delicate competition is attributed to the giant magnetic fluctuation inherent in the frustrated antiferromagnetic state. Therefore, the magnetoelastic instability is approached even under a small perturbation.
de Boissieu, M.*; Francoual, S.*; Minalkovi
, M.*; 柴田 薫; Baron, A. Q. R.*; Sidis, Y.*; 石政 勉*; Wu, D.*; Lograsso, T.*; Regnault, L.-P.*; et al.
Nature Materials, 6(12), p.977 - 984, 2007/12
被引用回数：42 パーセンタイル：81.31(Chemistry, Physical)局所構造及び(周期性又は準周期性)長距離秩序のそれぞれが格子振動に及ぼす影響を研究する目的でZn-Mg-Sc正20面体準結晶及びZn-Sc周期性1/1近似結晶の単結晶を用いた非弾性中性子,X-ray散乱実験を実施した。全体的な格子振動の相似性や横波分散関係に擬ギャップが共通して存在する等の定性的な相似性を別にすると、準結晶中と近似結晶中の格子振動には定量的な違いが観測された。例えば近似結晶中の格子振動の方が擬ギャップが大きくはっきりしている点である。またこれらの実験結果は精密原子構造モデルと振動型ペアポテンシャルをもとにしたシミュレーションと比較が行われよく再現されることが明らかになった。
Lu, L.*; 飯田 浩正; Li, Y.*; Ding, A.*; Zeng, Q.*; Huang, C.*; Wu, Y.*
no journal, ,
ポートリミターはITER(国際熱核融合炉)の重要な機器の一つであり、非常に複雑な形状を持っている。CAD図面から自動的にモンテカルロコードMCNPの入力を作成するプログラムMCAMを用いて、核解析を行うための詳細な入力を作成した。本発表は元図であるCAD図面のpreprocess及び変換された入力のvalidationの詳細なフローについて述べたものである。本作業が成功裏に行われたことは、複雑な機器のモンテカルロコード用入力を作成することにおいて、MCAMが、従来のマニュアル作業による入力作成に比べ、圧倒的に効率を高め、また正確さを増すことができることを示すものである。
亀島 敬; 小瀧 秀行; 神門 正城; 大東 出; 川瀬 啓悟; 福田 祐仁; Chen, L. M.*; 本間 隆之; 近藤 修司; Esirkepov, T. Z.; et al.
no journal, ,
レーザープラズマ電子加速は非常に高い電場を持っているが、加速空間が非常に短いという問題点を持っているため、その電子ビームの加速エネルギーは100MeV程度に制限されていた。近年、このレーザープラズマ電子加速が抱える問題点をキャピラリー放電管を用いることで大幅に解決がなされた。プラズマは密度が高いほど屈折率が低くなる特徴を利用して放電管の中でプラズマ密度を中心で薄く、その外周を高く分布させれば光ファイバーと同じ原理でレーザーは放電管内のプラズマ中を集光伝搬しながら相互作用する。ゆえに、加速空間を大幅に拡張することができる。この実験を2006年に中国工程物理研究院とKEK、及び原子力機構で共同実験を行い、キャピラリ放電管を用いて4.4Jのレーザーパルスの集光伝搬及び0.56GeVの電子ビームの生成に成功した。加えて、JAEAにて同様の実験を2007年に行い、1Jのレーザーパルスの集光伝搬及び電子ビームの発生に成功した。
Ding, F.*; 芦川 直子*; 福本 正勝; 片山 一成*; Mao, H.*; Ding, R.*; Xu, Q.*; Wu, J.*; Xie, C. Y.*; Luo, G.-N.*
no journal, ,
Castellated tungsten samples with different gap width and gap depth are exposed to the scrape-off-layer plasma with the material and plasma evaluation system (MAPES) to investigate effects of castellation configurations on impurity deposition and fuel retention. After the plasma exposure, composition and distribution of the impurity deposited on the inner surface of the gap are investigated. The composition and the distribution of the deposits have a strong dependence of the gap configuration. The amount of the deposits on the inner surface of the inverse trapezoid gap is small compared with that of the rectangular gap with the same top width. For all the samples, the amount of the deposits decreases with the gap width and depth.
