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論文

Stacking fault driven phase transformation in CrCoNi medium entropy alloy

He, H.*; Naeem, M.*; Zhang, F.*; Zhao, Y.*; Harjo, S.; 川崎 卓郎; Wang, B.*; Wu, X.*; Lan, S.*; Wu, Z.*; et al.

Nano Letters, 21(3), p.1419 - 1426, 2021/02

 被引用回数:3 パーセンタイル:0(Chemistry, Multidisciplinary)

In CrCoNi, a so-called medium-entropy alloy, an fcc-to-hcp phase transformation has long been anticipated. Here, we report an in situ loading study with neutron diffraction, which revealed a bulk fcc-to-hcp phase transformation in CrCoNi at 15 K under tensile loading. By correlating deformation characteristics of the fcc phase with the development of the hcp phase, it is shown that the nucleation of the hcp phase was triggered by intrinsic stacking faults. The confirmation of a bulk phase transformation adds to the myriads of deformation mechanisms available in CrCoNi, which together underpin the unusually large ductility at low temperatures.

論文

Selective removal of radiocesium from micaceous clay for post-accident soil decontamination by temperature-controlled Mg-leaching in a column

Yin, X.; Zhang, L.*; Meng, C.*; 稲葉 優介*; Wang, X.*; 二田 郁子; 駒 義和; 竹下 健二*

Journal of Hazardous Materials, 387, p.121677_1 - 121677_10, 2020/04

The effective and efficient removal of radioactive Cs from contaminated soil is highly urgent for the nuclear post-accident remediation. In present study, we achieved rapid Cs desorption from both a typical micaceous clay (i.e., vermiculitized biotite, VB) and actually contaminated soil by high-speed ion exchange through temperature-controlled continuous leaching with Mg-solutions in a column reactor. Cs-sorbed VB was firstly employed as a soil surrogate to explore the macro-Cs desorption process and micro-mechanism in detail.

論文

Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs

Xu, Z.*; Dai, G.*; Li, Y.*; Yin, Z.*; Rong, Y.*; Tian, L.*; Liu, P.*; Wang, H.*; Xing, L.*; Wei, Y.*; et al.

npj Quantum Materials (Internet), 5(1), p.11_1 - 11_7, 2020/02

 被引用回数:3 パーセンタイル:55.89(Materials Science, Multidisciplinary)

We use neutron scattering to study Vanadium (hole)-doped LiFe$$_{1-x}$$V$$_{x}$$As. In the undoped state, LiFeAs exhibits superconductivity at $$T_mathrm{c} = 18$$ K and transverse incommensurate spin excitations similar to electron overdoped iron pnictides. Upon Vanadium doping to form LiFe$$_{0.955}$$V$$_{0.045}$$, the transverse incommensurate spin excitations in LiFeAs transform into longitudinally elongated ones in a similar fashion to that of potassium (hole)-doped Ba$$_{0.7}$$K$$_{0.3}$$Fe$$_{2}$$As$$_{2}$$ but with dramatically enhanced magnetic scattering and elimination of superconductivity. This is different from the suppression of the overall magnetic excitations in hole-doped BaFe$$_{2}$$As$$_{2}$$ and the enhancement of superconductivity near optimal hole doping. These results are consistent with density function theory plus dynamic mean field theory calculations, suggesting that Vanadium doping in LiFeAs may induce an enlarged effective magnetic moment $$S_mathrm{eff}$$ with a spin crossover ground state arising from the inter-orbital scattering of itinerant electrons.

論文

Coexistence of ferromagnetic and stripe-type antiferromagnetic spin fluctuations in YFe$$_{2}$$Ge$$_{2}$$

Wo, H.*; Wang, Q.*; Shen, Y.*; Zhang, X.*; Hao, Y.*; Feng, Y.*; Shen, S.*; He, Z.*; Pan, B.*; Wang, W.*; et al.

Physical Review Letters, 122(21), p.217003_1 - 217003_5, 2019/05

 被引用回数:2 パーセンタイル:35.62(Physics, Multidisciplinary)

We report neutron scattering measurements of single-crystalline YFe$$_{2}$$Ge$$_{2}$$ in the normal state, which has the same crystal structure as the 122 family of iron pnictide superconductors. YFe$$_{2}$$Ge$$_{2}$$ does not exhibit long-range magnetic order but exhibits strong spin fluctuations. Like the iron pnictides, YFe$$_{2}$$Ge$$_{2}$$ displays anisotropic stripe-type antiferromagnetic spin fluctuations at ($$pi, 0, pi$$). More interesting, however, is the observation of strong spin fluctuations at the in-plane ferromagnetic wave vector ($$0, 0, pi$$). These ferromagnetic spin fluctuations are isotropic in the ($$H, K$$) plane, whose intensity exceeds that of stripe spin fluctuations. Both the ferromagnetic and stripe spin fluctuations remain gapless down to the lowest measured energies. Our results naturally explain the absence of magnetic order in YFe$$_{2}$$Ge$$_{2}$$ and also imply that the ferromagnetic correlations may be a key ingredient for iron-based materials.

論文

Uniaxial pressure effect on the magnetic ordered moment and transition temperatures in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ ($$T$$ = Co,Ni)

Tam, D. M.*; Song, Y.*; Man, H.*; Cheung, S. C.*; Yin, Z.*; Lu, X.*; Wang, W.*; Frandsen, B. A.*; Liu, L.*; Gong, Z.*; et al.

Physical Review B, 95(6), p.060505_1 - 060505_6, 2017/02

 被引用回数:18 パーセンタイル:75.96(Materials Science, Multidisciplinary)

We use neutron diffraction and muon spin relaxation to study the effect of in-plane uniaxial pressure on the antiferromagnetic (AF) orthorhombic phase in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ and its Co- and Ni-substituted members near optimal superconductivity. In the low-temperature AF ordered state, uniaxial pressure necessary to detwin the orthorhombic crystals also increases the magnetic ordered moment, reaching an 11% increase under 40 MPa for BaFe$$_{1.9}$$Co$$_{0.1}$$As$$_2$$, and a 15% increase for BaFe$$_{1.915}$$Ni$$_{0.085}$$As$$_2$$. We also observe an increase of the AF ordering temperature ($$T_N$$) of about 0.25 K/MPa in all compounds, consistent with density functional theory calculations that reveal better Fermi surface nesting for itinerant electrons under uniaxial pressure. The doping dependence of the magnetic ordered moment is captured by combining dynamical mean field theory with density functional theory, suggesting that the pressure-induced moment increase near optimal superconductivity is closely related to quantum fluctuations and the nearby electronic nematic phase.

口頭

異なる中性子回折装置を用いた鉄鋼材料バルク集合組織の評価と比較

徐 平光; 鈴木 裕士; 目時 直人; 塩田 佳徳; 鈴木 徹也*; Yin, F. X.*; 秋田 貢一

no journal, , 

中性子回折は金属材料のバルク集合組織を測定できるが、測定精度は中性子回折装置に依存している。以前より原子力機構では、中性子応力測定装置RESA, RESAIIを利用することによりバルク材の集合組織測定を行ってきたが、近年の集合組織測定に対するニーズ増加に対応するため、他の回折装置で良好な集合組織測定が可能であるか検討した。多目的単色熱中性子ビームポートMUSASIを利用した集合組織測定を行った結果、集合組織測定実験への応用が十分可能であることを確認した。

口頭

Rapid removal of cesium from Fukushima contaminated soil by hydrothermal treatment with multivalent cations

Yin, X.; 駒 義和; 稲葉 優介*; 竹下 健二*

no journal, , 

福島第一原子力発電所の事故によりセシウムで汚染した土壌の除染と減容は大きな課題である。本研究において著者らは、カラム法により粘土質土壌からセシウムを高速に除去する連続水熱処理プロセスの開発を目指した。福島県における事故後の処理に向けての新しい知見が得られた。

口頭

Rapid removal of cesium from vermiculite by collapsing the interlayers with hydrothermal column system

Yin, X.; 駒 義和; 稲葉 優介*; 竹下 健二*

no journal, , 

The decontamination and volume reduction of Cs contaminated soil by efficient Cs removal remains a great challenge after the Fukushima Daiichi Nuclear Power Station accident. In present work, we studied the removal of Cs from the clay soils by treating with hydrothermal cations in a column system. The new results showed that Cs can be selectively removed from its collapsed interlayers in vermiculite by hydrothermally heating at 150 degrees.

口頭

Rapid desorption of radioactive Cs from contaminated soil by high-speed ion exchange in subcritical water

Yin, X.; 駒 義和; 稲葉 優介*; 竹下 健二*

no journal, , 

除染で発生した汚染土壌の総量は福島県内で約2200万m$$^{3}$$と推定されている。これら廃棄物は仮置き場や除染現場にて一時的に保管された後、福島県内の中間貯蔵施設で最大30年間保管され、最終的には県外で最終処分される予定である。中間貯蔵あるいは最終処分において、汚染度の高い土壌は安全性、経済性を考慮して廃棄物減容化と安定した最終処分形態の検討が必要である。本報では土壌分級物に含まれる粘土鉱物に強力に吸着したCsのカラム法による連続回収について報告する。

口頭

Rapid desorption of radioactive Cs from contaminated soil by ion exchange with subcritical water in column

Yin, X.; 駒 義和; 稲葉 優介*; 竹下 健二*

no journal, , 

除染で発生した汚染土壌の総量は福島県内で約2200万m$$^{3}$$と推定されている。これら廃棄物は仮置き場や除染現場にて一時的に保管された後、福島県内の中間貯蔵施設で最大30年間保管され、最終的には県外で最終処分される予定である。中間貯蔵あるいは最終処分において、汚染度の高い土壌は安全性, 経済性を考慮して廃棄物減容化と安定した最終処分形態の検討が必要である。本報では土壌分級物に含まれる粘土鉱物に強力に吸着したCsのカラム法による連続回収について報告する。

口頭

Removal of radioactive cesium from Fukushima contaminated soil by hot-pressing water extraction in a column

Yin, X.; 駒 義和; 稲葉 優介*; 竹下 健二*

no journal, , 

The decontamination and volume reduction of Cs contaminated soil remains a great challenge after the Fukushima Daiichi Nuclear Power Station accident. In present study, the authors aim to develop the continuous hydrothermal treatment process to remove radioactive Cs rapidly from the clay soils by a column system.

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