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論文

Unique deformation behavior of ultrafine-grained 304 stainless steel at 20 K

Mao, W.*; Gong, W.; 川崎 卓郎; Gao, S.*; 伊東 達矢; 山下 享介*; Harjo, S.; Zhao, L.*; Wang, Q.*

Scripta Materialia, 264, p.116726_1 - 116726_6, 2025/07

 被引用回数:0

An ultrafine-grained 304 austenitic stainless steel exhibited pronounced serrated Luders deformation at 20 K, with stress and temperature oscillations reaching 200 MPa and 20 K. ${it In-situ}$ neutron diffraction and digital image correlation revealed discontinuous Luders band propagation and burst martensite formation. During deformation, austenite phase stress remained lower than at upper yielding, indicating elastic behavior. Notably, martensite phase stress stayed lower than austenite until fracture, likely due to stress relaxation from burst martensitic transformation at 20 K. The low martensite stress delayed brittle fracture until austenite plastically yielded during uniform deformation.

論文

Role of solute hydrogen on mechanical property enhancement in Fe-24Cr-19Ni austenitic steel; An ${it in situ}$ neutron diffraction study

伊東 達矢; 小川 祐平*; Gong, W.; Mao, W.*; 川崎 卓郎; 岡田 和歩*; 柴田 曉伸*; Harjo, S.

Acta Materialia, 287, p.120767_1 - 120767_16, 2025/04

 被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)

Incorporating solute hydrogen into Fe-Cr-Ni-based austenitic stainless steels enhances both strength and ductility, providing a promising solution to hydrogen embrittlement by causing solid-solution strengthening and assisting deformation twinning. However, its impacts on the relevant lattice defects evolution (${it i.e.}$, dislocations, stacking faults, and twins) during deformation remains unclear. This study compared the tensile deformation behavior in an Fe-24Cr-19Ni (mass%) austenitic steel with 7600 atom ppm hydrogen-charged (H-charged) and without hydrogen-charged (non-charged) using ${it in situ}$ neutron diffraction. Hydrogen effects on the lattice expansion, solid-solution strengthening, stacking fault probability, stacking fault energy, dislocation density, and strain/stress for twin evolution were quantitatively evaluated to link them with the macroscale mechanical properties. The H-charged sample showed improvements in yield stress, flow stress, and uniform elongation, consistent with earlier findings. However, solute hydrogen exhibited minimal influences on the evolution of dislocation and stacking fault. This fact contradicts the previous reports on hydrogen-enhanced dislocation and stacking fault evolutions, the latter of which can be responsible for the enhancement of twinning. The strain for twin evolution was smaller in the H-charged sample compared to the non-charged one. Nevertheless, when evaluated as the onset stress for twin evolution, there was minimal change between the two samples. These findings suggest that the increase in flow stress due to the solid-solution strengthening by hydrogen is a root cause of accelerated deformation twinning at a smaller strain, leading to an enhanced work-hardening rate and improved uniform elongation.

論文

Study on the effect of radiation-resistant resin on water radiolysis

伊藤 辰也; 永石 隆二; 桑野 涼*; 神戸 正雄*; 吉田 陽一*

Radiation Physics and Chemistry, 226, p.112198_1 - 112198_5, 2025/01

 被引用回数:0 パーセンタイル:0.00(Chemistry, Physical)

近年、放射線照射実験や非密封放射性同位元素実験用の容器として、ポリイミドやポリエーテルエーテルケトンなどの耐放射線性樹脂の使用が増えている。しかし、水の分解生成物と樹脂との相互作用の可能性が見つかり、樹脂が放射線場における水中の反応に影響を及ぼすことが懸念された。その相互作用を明らかにするために、$$gamma$$線による水の放射線分解における重クロム酸イオン(Cr$$_{2}$$O$$_{7}$$$$^{2-}$$)の還元と過酸化水素(H$$_{2}$$O$$_{2}$$)の生成を樹脂の有無で比較した。同一線量で樹脂ありの水溶液中のCr$$_{2}$$O$$_{7}$$$$^{2-}$$還元量は樹脂なしの場合よりも大きくなり、樹脂によってCr$$_{2}$$O$$_{7}$$$$^{2-}$$還元が促進されることを示した。一方、電子捕捉剤の有無にかかわらず、純水中のH$$_{2}$$O$$_{2}$$生成は樹脂の有無にほとんど依存しなかった。これらは、放射線場において水と接触した樹脂とヒドロキシルラジカルとの相互作用を示唆している。

論文

Martensitic transformation and shape memory effect in Mn-rich Cu-Mn-Al alloys

伊東 達矢; Xu, S.*; Xu, X.*; 大森 俊洋*; 貝沼 亮介*

Shape Memory and Superelasticity, 9 Pages, 2025/00

The microstructure, crystal structures, cold workability, and martensitic transformation temperatures of several Cu$$_{100-{it x}-{it y}}$$Mn$$_{it x}$$Al$$_{it y}$$ (40 $$leq$$ ${it x}$ $$leq$$ 55; 10 $$leq$$ ${it y}$ $$leq$$ 13; at%) alloys were analyzed. For the first time, martensitic transformation was revealed Mn-rich Cu-Mn-Al alloys. The surface relief of the martensite phase reversibly appeared and disappeared during cooling and heating, along with small thermal hysteresis, implying a thermoelastic transformation. The crystal structures of the parent and martensite phases are B2 and 2M(BCT), respectively, with c$/a being approximately 1.35. Cold workability improves with decreasing Al content, exhibiting a trend similar to that observed for previously reported Cu-rich Cu-Al-Mn shape memory alloys. The martensitic transformation temperatures decrease with increasing Al content and increase with increasing Mn content. These results are consistent with the stability trends of the parent body-centered cubic phase in the phase diagram at high temperature. The shape memory effect with a recovery strain of 1.3% was observed in a 5.0% pre-stretched Cu$_{39}$$Mn$$_{50}$$Al$$_{11}$$ (at%) sample. This alloy demonstrates moderate cold workability and cost-effectiveness, exhibiting potential as an alternative for conventional shape memory alloys in various applications.

論文

Surface depth analysis of chemical changes in random copolymer thin films composed of hydrophilic and hydrophobic silicon-based monomers induced by plasma treatment as studied by hard X-ray photoelectron spectroscopy and neutron reflectivity measurements

山本 勝宏*; 今井 達也*; 河合 純希*; 伊藤 恵利*; 宮崎 司*; 宮田 登*; 山田 悟史*; 瀬戸 秀紀*; 青木 裕之

ACS Applied Materials & Interfaces, 16(48), p.66782 - 66791, 2024/11

 被引用回数:0 パーセンタイル:0.00(Nanoscience & Nanotechnology)

In this study, a silicon-based copolymer, poly(tris(trimethylsiloxy)-3-methacryloxypropylsilane)-co-poly(N,N-dimethyl acrylamide), thin film was subjected to plasma surface treatment to make its surface hydrophilic (biocompatible). Neutron reflectivity (NR) measurement of the plasma-treated thin film showed a decrease in the film thickness (etching width: similar to 20 nm) and an increase in the scattering length density (SLD) near the surface (similar to 15 nm). The region with a considerably high SLD adsorbed water (D$$_{2}$$O) from its saturated vapor, indicating its superior surface hydrophilicity. Nevertheless of the hydrophilicity, the swelling of the thin film was suppressed. Hard X-ray photoelectron spectroscopy (HAXPES) performed at various takeoff angles revealed that the thin-film surface (similar to 20 nm depth) underwent extensive oxidation. NR and HAXPES analysis quantitatively yielded the depth profiling of elemental compositions in a few tens of nm scale. Si oxidation and hydrogen elimination (probably CH$$_{3}$$ groups) in the vicinity of the surface region increased the SLD and decreased the hydrophobicity. A combination of Soft X-ray photoelectron spectroscopy and NR measurements revealed the surface chemical composition and mass density. It was considered that the surface near the film was chemically composed close to SiO$$_{2}$$, forming a gel-like (three-dimensional network) structure that is hydrophilic and suppresses swelling due to moisture, indicating it can be expected to maintain stable hydrophilicity on the film surface.

論文

${it In situ}$ neutron diffraction study to elucidate hydrogen effect on the deformation mechanism in Type 310S austenitic stainless steel

伊東 達矢; 小川 祐平*; Gong, W.; Mao, W.*; 川崎 卓郎; 岡田 和歩*; 柴田 曉伸*; Harjo, S.

Proceedings of the 7th International Symposium on Steel Science (ISSS 2024), p.237 - 240, 2024/11

Hydrogen embrittlement has long been an obstacle to the development of safe infrastructure. However, in contrast to hydrogen's embrittling effect, recent research has revealed that the addition of hydrogen improves both the strength and uniform elongation of AISI Type 310S austenitic stainless steel. A detailed understanding of how hydrogen affects the deformation mechanism of this steel could pave the way for the development of more advanced materials with superior properties. In the present study, ${it in situ}$ neutron diffraction experiments were conducted on Type 310S steel with and without hydrogen-charged to investigate the effect of hydrogen on the deformation mechanism. In addition to the effect of solid-solution strengthening by hydrogen, the q-value, a parameter representing the proportion of edge and screw dislocations in the accumulated dislocations, was quantitatively evaluated using CMWP analysis on neutron diffraction patterns. The comparison of q-values between the hydrogen-charged and non-charged samples reveals that hydrogen has minimal effect on dislocation character in Type 310S steel.

論文

Martensitic transformation-governed Luders deformation enables large ductility and late-stage strain hardening in ultrafine-grained austenitic stainless steel at low temperatures

Mao, W.*; Gao, S.*; Gong, W.; 川崎 卓郎; 伊東 達矢; Harjo, S.; 辻 伸泰*

Acta Materialia, 278, p.120233_1 - 120233_13, 2024/10

 被引用回数:12 パーセンタイル:87.44(Materials Science, Multidisciplinary)

Using a hybrid method of in situ neutron diffraction and digital image correlation, we found that ultrafine-grained 304 stainless steel exhibits Luders deformation after yielding, in which the deformation behavior changes from a cooperation mechanism involving dislocation slip and martensitic transformation to one primarily governed by martensitic transformation, as the temperature decreases from 295 K to 77 K. Such martensitic transformation-governed Luders deformation delays the activation of plastic deformation in both the austenite parent and martensite product, resulting in delayed strain hardening. This preserves the strain-hardening capability for the later stage of deformation, thereby maintaining a remarkable elongation of 29% while achieving a high tensile strength of 1.87 GPa at 77 K.

論文

Polarized and unpolarized neutron scattering for magnetic materials at the triple-axis spectrometer PONTA in JRR-3

中島 多朗*; 齋藤 開*; 小林 尚暉*; 川崎 卓郎; 中村 龍也; 古川 はづき*; 浅井 晋一郎*; 益田 隆嗣*

Journal of the Physical Society of Japan, 93(9), p.091002_1 - 091002_5, 2024/09

 被引用回数:2 パーセンタイル:68.78(Physics, Multidisciplinary)

Neutron scattering is a powerful tool to study magnetic structures and cross-correlated phenomena originated from symmetry of the magnetic structures in matter. Among a number of neutron scattering techniques, polarized neutron scattering is quite sensitive to the orientations of the magnetic moments, which are essential to understand microscopic mechanisms of the spin-driven emergent phenomena. Here, we present POlarized Neutron Triple-Axis spectrometer PONTA in the Japan Research Reactor 3 (JRR-3), and show the present capabilities of polarized and unpolarized neutron scattering by introducing recent results from the instrument.

論文

Comprehensive extraction study using $$N,N$$-dioctylthiodiglycolamic acid; Effect of S donor on metal extraction

下条 晃司郎; 藤原 伊織*; 斉藤 拓巳*; 大島 達也*

Analytical Sciences, 40(8), p.1429 - 1436, 2024/08

 被引用回数:0 パーセンタイル:0.00(Chemistry, Analytical)

アミド基とカルボン酸をチオエーテル鎖で結合したソフトベース硫黄ドナー配位子である$$N,N$$-ジオクチルチオジグリコール酸(T-DODGAA)を用いて56種類の金属イオンの抽出能力が包括的に調査し、エーテル性酸素原子よりなるハードベースドナー配位子であるN, N-ジオクチルジグリコール酸(DODGAA)との抽出能力を比較した。チオジグリコール酸骨格のp$$K_{a}$$は、電位差滴定により水(0.1M LiCl、25$$^{circ}$$C)中で3.71$$pm$$0.06と算出され、これは、T-DODGAAがDODGAA (p$$K_{a}$$ = 3.54$$pm$$0.03)よりわずかに弱い酸であることを示す。T-DODGAAはプロトン交換反応により56種類の金属イオンから様々な金属イオンを定量的に抽出することができる。T-DODGAAは、Hf(IV)、Cr(III)、Fe(III)、Ni(II)、Cu(II)、Pd(II)、Ag(I)、Au(III)、Hg(II)、Al(III)、Ga(III)、特にソフト金属イオンにたいして高い抽出能を有する。さらに、湿式製錬や金属リサイクルにおけるT-DODGAAの実用可能性を実証するために、金属混合抽出システムにおけるSc(III)、Ni(II)、Co(II)、Pd(II)、Au(III)、In(III)およびGa(II)のようなレアメタルの選択的分離実験を行った。

論文

Retention of hydrogen bubbles generated from water radiolysis in carbonate slurry

伊藤 辰也; 永石 隆二; 桑野 涼*

Nuclear Technology, 210(8), p.1427 - 1443, 2024/08

 被引用回数:0 パーセンタイル:0.00(Nuclear Science & Technology)

福島第一原子力発電所の多核種除去設備における凝集沈殿(共沈)プロセスから排出される放射性廃棄物のような強アルカリ条件下で、水の放射線分解によって発生した水素(H$$_{2}$$)気泡の保持を、マグネシウムとカルシウムの混合沈殿物である懸濁物固体(SS)からなる炭酸塩スラリーの高粘度懸濁液中で定量的に研究した。親水性の異なる2種類の炭酸塩スラリー、親水性の「現行型」と疎水性の「返送型」についてH$$_{2}$$保持特性を評価し、それらの特性を別の懸濁液であるベントナイトの粘土懸濁液の特性と比較した。SS粒子表面の化学吸着量とスラリー中のH$$_{2}$$Oの量の比較から、SS粒子間でH$$_{2}$$O分子が共有されている必要があり、この共有により粘土懸濁液中で微細な粘土鉱物間の静電的な結合が形成する粘性とは異なる構造粘性が形成されることが確認された。スラリー中のH$$_{2}$$気泡の保持は、$$^{60}$$Co$$gamma$$線照射後のスラリーの撹拌前後で観測されたH$$_{2}$$発生量の差から評価した。親水性スラリー、疎水性スラリー、粘土懸濁液、処理水の保持特性の比較から、親水性スラリー中のH$$_{2}$$気泡は構造粘性だけでなく立体障害によっても保持されると示唆された。

論文

Corrigendum to "Development of 0.5 mm gauge size radial collimators for high-pressure neutron diffraction experiments at PLANET in J-PARC" [Nucl. Instrum. Methods Phys. Res. A 1059 (2024) 168956]

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, 1064, p.169448_1 - 169448_9, 2024/07

 被引用回数:0 パーセンタイル:0.00(Instruments & Instrumentation)

著者らは、抄録と要約で標準的なダブルトロイダルアンビルのカップ径が1.5mmであると説明していることを遺憾に思う。これは誤りで、標準的な直径は4.0mmである。ご迷惑をおかけしたことをお詫びする。

論文

Polarized neutron diffraction study on UPt$$_{2}$$Si$$_{2}$$

今 布咲子*; 田端 千紘; 齋藤 開*; 中島 多朗*; 日高 宏之*; 柳澤 達也*; 網塚 浩*

Journal of the Physical Society of Japan, 93(4), p.044701_1 - 044701_11, 2024/04

 被引用回数:0 パーセンタイル:0.00(Physics, Multidisciplinary)

We investigated the magnetic structure of the antiferromagnetic (AFM) ordered state ($$T_{rm N}$$ $$sim$$ 34 K) in tetragonal UPt$$_{2}$$Si$$_{2}$$ using polarized and unpolarized neutron diffraction. Previous neutron scattering studies reported that this system possesses a simple AFM structure with a propagation vector, Q= 0, and the ordered magnetic moments aligned along the c-axis. By contrast, our latest resonant X-ray scattering (RXS) experiments have revealed that the magnetic structure is modulated by the charge-density-wave (CDW) order, which emerges in one of the two Pt atomic layers in the unit cell below $$sim$$320 K. The modulation is characterized by a transverse wave in the c-plane, with the propagation vector of the CDW order, q$$_{rm CDW}$$ = ($$sim$$0.42, 0, 0). In this study using neutron scattering, we observed that the superlattice reflections specified by q$$_{rm CDW}$$ develop below $$T_{rm N}$$, in addition to the magnetic reflections with Q= 0, thereby further confirming the presence of modulation in the AFM structure of this system. From detailed analyses, we revealed that the amplitude of the transverse-wave magnetic modulation is 0.72(2)$$mu$$$$_{rm B}$$/U, which is quantitative information that can not be obtained through RXS experiments. This implies that the CDW drives the ordered magnetic moments to be tilted up to 20$$^{circ}$$ in the AFM state. The observations strongly suggest that the magnetism of UPt$$_{2}$$Si$$_{2}$$ is heavily influenced by the hybridization effects between the $$5f$$ electrons of U and the 5d electrons of Pt.

論文

Adsorption behavior of platinum-group metals and Co-existing metal ions from simulated high-level liquid waste using HONTA and Crea impregnated adsorbent

大沢 直樹*; Kim, S.-Y.*; 久保田 真彦*; Wu, H.*; 渡部 創; 伊藤 辰也; 永石 隆二

Nuclear Engineering and Technology, 56(3), p.812 - 818, 2024/03

 被引用回数:2 パーセンタイル:57.00(Nuclear Science & Technology)

An impregnated silica-based adsorbent was prepared by combining HONTA extractant, Crea extractant, and macroporous silica polymer composite particles (SiO$$_{2}$$-P). The performance of platinum-group metals adsorption and separation on prepared (HONTA + Crea)/SiO$$_{2}$$-P adsorbent was assessed by batch-adsorption and chromatographic separation studies. (HONTA + Crea)/SiO$$_{2}$$-P adsorbent showed high adsorption performance of Pd(II) owing to an affinity between Pd(II) and Crea extractant based on the Hard and Soft Acids and Bases theory. The chromatographic experiment showed that Pd(II) was recovered entirely from the feed solution using 0.2 M thiourea in 0.1 M HNO$$_{3}$$. Possibility of recovery of Zr(IV), Mo(VI), and Re(VII) was also observed using the (HONTA + Crea)/SiO$$_{2}$$-P adsorbent.

論文

Measurement of the neutron capture cross section of $$^{185}$$Re in the keV energy region

片渕 竜也*; 佐藤 八起*; 武部 花凛*; 井頭 政之*; 梅澤 征悟*; 藤岡 諒*; 齋藤 辰宏*; 岩本 信之

Journal of Nuclear Science and Technology, 61(2), p.224 - 229, 2024/02

 被引用回数:0 パーセンタイル:0.00(Nuclear Science & Technology)

Measurements of the neutron capture cross section of $$^{185}$$Re have been limited in the keV energy region. In addition, existing measured data have discrepancies. In this study, the neutron time-of-flight method was employed to measure the capture cross section of $$^{185}$$Re at Tokyo Institute of Technology. The capture $$gamma$$-rays were detected with a large volume NaI(Tl) detector. The pulse-height weighting technique was applied to obtain the capture yield. The present results were corrected for neutron scattered effects and impurities in the sample. The measured cross sections were determined with the standard capture cross section of gold in the energy range from 15 to 90 keV, and compared with measured and evaluated data. The results of the measurement provided improved accuracy relative to previous studies in the keV energy range.

論文

Experimental determination of phase equilibria in the Mn-Zn binary system

今富 大介*; 石川 遼典*; 仲田 玲*; 伊東 達矢; Han, K.*; 長迫 実*; Xu, X.*; 大森 俊洋*; 貝沼 亮介*

Journal of Phase Equilibria and Diffusion, 45(1), p.3 - 17, 2024/02

 被引用回数:1 パーセンタイル:12.80(Chemistry, Physical)

Mn-Zn二元系における相平衡を、組成分析、結晶構造解析、熱分析により実験的に決定した。これまでの報告と比較し、$$beta$$相、$$varepsilon$$相、$$delta$$相の存在領域に違いが見られた。$$beta$$相の領域から急冷した試料で$$delta$$Mn相と同じ不規則な体心立方構造が確認されたため、$$beta$$-B2の単相域は確認できなかった。先行研究において、$$varepsilon$$相が$$varepsilon$$,$$varepsilon_{1}$$,$$varepsilon_{2}$$相に分離しているかどうかが論争になっていきたが、拡散対といくつかの合金組成の調査により、$$varepsilon$$相、$$varepsilon_{1}$$相、$$varepsilon_{2}$$相は分離しておらず、単一の$$varepsilon$$相となっていることが示された。さらに、熱分析によって対応する不変系反応が検出されなかったことから、$$delta$$相はZn過剰領域には存在しない。

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

 被引用回数:2 パーセンタイル:46.61(Instruments & Instrumentation)

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

エネルギーロスの小さなPd$$_{2}$$MnGaメタ磁性形状記憶合金の開発

伊東 達矢; Xu, X.*; 大森 俊洋*; 貝沼 亮介*

物性研だより, 63(3), p.8 - 10, 2023/10

メタ磁性形状記憶合金は磁場により駆動することが出来る形状記憶合金であり、センサーやアクチュエーター等での応用が期待されている。しかし、これまでに開発されてきた合金系ではマルテンサイト変態に伴うエネルギーロスが大きいという問題点があった。近年、我々の研究グループではPd$$_2$$MnGa合金において初めて相変態によるエネルギーロスの小さなメタ磁性形状記憶合金を発見した。本稿ではその内容を紹介する。

論文

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

山本 風海; 金正 倫計; 林 直樹; Saha, P. K.; 田村 文彦; 山本 昌亘; 谷 教夫; 高柳 智弘; 神谷 潤一郎; 菖蒲田 義博; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 被引用回数:7 パーセンタイル:74.40(Nuclear Science & Technology)

J-PARC 3GeVシンクロトロン(RCS)は、最大1MWの大強度ビームを25Hzという早い繰り返しで中性子実験及び下流の主リングシンクロトロンに供給することを目的に設計された。2007年の加速器調整運転開始以降、RCSではビーム試験を通じて加速器の設計性能が満たされているかの確認を進め、必要に応じてより安定に運転するための改善を行ってきた。その結果として、近年RCSは1MWのビーム出力で連続運転を行うことが可能となり、共用運転に向けた最後の課題の抽出と対策の検討が進められている。本論文ではRCSの設計方針と実際の性能、および改善点について議論する。

論文

Two-step Mott transition in Ni(S,Se)$$_2$$; $$mu$$SR studies and charge-spin percolation model

Sheng, Q.*; 金子 竜也*; Yamakawa, Kohtaro*; Guguchia, Z.*; Gong, Z.*; Zhao, G.*; Dai, G.*; Jin, C.*; Guo, S.*; Fu, L.*; et al.

Physical Review Research (Internet), 4(3), p.033172_1 - 033172_14, 2022/09

A pyrite system NiS$$_{2-x}$$Se$$_x$$ exhibits a bandwidth controlled Mott transition via (S,Se) substitutions in a two-step process: the antiferromagnetic insulator (AFI) to antiferromagnetic metal (AFM) transition at $$xsim$$0.45 followed by the AFM to paramagnetic metal (PMM) transition at $$xsim$$1.0. Among a few other Mott systems which exhibit similar two-step transitions, Ni(S,Se)$$_2$$ is of particular interest because a large intermediate AFM region in the phase diagram would provide unique opportunities to study the interplay between the spin and charge order. By comparing and combining our muon spin relaxation studies and previous neutron scattering studies, here we propose a picture where the spin order is maintained by the percolation of "nonmetallic" localized and dangling Ni moments surrounded by S, while the charge transition from AFI to AFM is caused by the percolation of the conducting paths generated by the Ni-Se-Ni bonds.

論文

Extraction behavior of a novel functionalized ionic liquid for separation of platinum group metals from aqueous nitric acid solution

伊藤 辰也; 大杉 遥*; 大沢 直樹*; 高橋 正幸*; Kim, S.-Y.*; 永石 隆二

Analytical Sciences, 38(1), p.91 - 97, 2022/01

 被引用回数:3 パーセンタイル:22.50(Chemistry, Analytical)

高レベル放射性廃液(HLLW)などの硝酸水溶液から白金族元素(Ru, Rh, Pd)を効果的かつ効率的に抽出するために、ソフトなSドナーを含有するチオジグリコールアミド酸を修飾した新規イオン液体(IL)を合成した。このILは約100%の抽出率で迅速なPd(II)の抽出を可能にした。Ru(III)及びRh(III)の抽出は、Pd(II)より遅いものの、温度上昇によって抽出速度が加速した。50$$^{circ}$$CにおけるRu(III)とRh(III)の抽出はそれぞれ4hと8h以内に平衡に達し、抽出系に補助剤やその他の方法を使用しなくても抽出率は90%を超えた。さらに、このILは50$$^{circ}$$Cにおいて2h以内に模擬HLLWから90%以上のRu(III)、Rh(III)及びPd(II)を抽出可能だった。

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