仲村 龍介 (ナカムラ リュウスケ)

NAKAMURA Ryusuke

写真a

取得学位 【 表示 / 非表示

  • 博士(工学)  東北大学  2004年03月

学外略歴 【 表示 / 非表示

  • 東北大学  金属材料研究所  研究員   2004年04月 ~ 2005年03月

  • 大阪大学  産業科学研究所  研究員   2005年04月 ~ 2005年08月

  • 大阪大学  産業科学研究所  特任助手   2005年09月 ~ 2006年05月

  • 大阪大学  産業科学研究所  助手   2006年05月 ~ 2007年03月

  • 大阪大学  産業科学研究所  助教   2007年04月 ~ 2012年02月

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所属学会・委員会 【 表示 / 非表示

  • 日本金属学会  

  • 日本鉄鋼協会  

  • 応用物理学会  

研究分野(科研費分類) 【 表示 / 非表示

  • 構造・機能材料

 

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  • Electron diffraction radial distribution function analysis of amorphous boron carbide synthesized by ion beam irradiation and chemical vapor deposition

    Ishimaru M., Nakamura R., Zhang Y., Weber W.J., Peterson G.G., Ianno N.J., Nastasi M.

    Journal of the European Ceramic Society  Journal of the European Ceramic Society  42 (2)   376 ~ 382  2022年02月

    10.1016/j.jeurceramsoc.2021.10.020  共著  共同(副担当)

    [概要]

    Amorphous boron carbide (a-BxC) networks consist of light elements, and their low atomic scattering factors makes structural analysis by x-ray diffraction difficult. Electron diffraction has an advantage of detecting the light elements, because of the strong interaction between the matter and electrons. We prepared a-BxC by ion beam technologies and plasma-enhanced chemical vapor deposition, and characterized their structures via atomic pair-distribution functions derived from electron diffraction intensity profiles. It was found that a pentagonal pyramid is the most favorable cluster in a-B4C generated by ion irradiation, while C[sbnd]C homonuclear bonds were formed in the deposited a-BxC thin film. X-ray photoemission spectroscopy revealed that the a-BxC thin film possesses more carbon than B4C, which is responsible for the formation of the homonuclear bonds.

  • Explosive crystallization of sputter-deposited amorphous germanium films by irradiation with an electron beam of SEM-level energies

    Nakamura R., Matsumoto A., Ishimaru M.

     Journal of Applied Physics  129 (21)   215301.1 ~ 215301.6  2021年06月

    10.1063/5.0052142  共著  共同(主担当)

    [概要]

    The crystallization of sputter-deposited substrate-free films of amorphous germanium was induced by electron irradiation at SEM-level energies of less than 20 keV at ambient temperature using an electron probe microanalyzer. Instantaneous crystallization, referred to as explosive crystallization, occurred consistently at 2-20 keV; the threshold of electron fluxes is 1015-1016 m−2 s−1, which is five to six orders of magnitude lower than those at 100 keV reported previously. This process is expected to be advantageous in the production of polycrystalline Ge films since it is rapid, requires little energy, and results in negligible damage to the substrate.

  • Permeation and diffusion of hydrogen in vanadium using deoxidation and glow-discharge surface cleaning techniques

    Fujimura N., Asano K., Nakamura R., Iijima Y.

     Journal of Membrane Science  614    2020年11月

    10.1016/j.memsci.2020.118522  共著  共同(副担当)

    [概要]

    Vanadium (V) is an attractive hydrogen separation membrane material. However, its diffusion behavior under hydrogen permeation is not well understood mainly because of surface oxidation. Here, we have attempted to observe the permeation of hydrogen through V by subjecting V samples to different surface treatments e.g., electropolishing and plasma-induced cleaning using a glow-discharge technique. We have achieved a high flux of hydrogen controlled by long-range diffusion under a low hydrogen potential at 723–973 K. The diffusion coefficients of hydrogen in defect-free and high-purity samples analyzed from the permeation curves at 823–973 K are almost consistent with the literature data obtained by Gorsky effect and absorption measurements. However, the activation energy of diffusion (19 kJ mol−1) is 8–14 kJ mol−1 higher than the literature values. This difference in activation energy suggests that permeation through the active surface of V is highly sensitive to trapping by oxygen—a slight amount of oxygen dissolved from a very thin native oxide layer would segregate near the surface to trap hydrogen. Furthermore, we have found that residual strain, grain boundaries, and lattice defects, induced by mechanical deformation, reduce the flux and retard the diffusion considerably.

  • Dual crystallization modes of sputter-deposited amorphous SiGe films

    Okugawa M., Nakamura R., Numakura H., Ishimaru M., Yasuda H.

     Journal of Applied Physics  128 (1)   015303.1 ~ 015303.9  2020年07月

    10.1063/5.0010202  共著  共同(主担当)

    [概要]

    The crystallization behavior of sputter-deposited films of amorphous Si (a-Si) and SiGe alloys (a-SiGe) induced by electron irradiation at room temperature and by thermal annealing was investigated by in situ transmission electron microscopy. On electron irradiation at room temperature, extremely rapid crystallization, so-called explosive crystallization, occurred at a higher electron flux but not at a lower electron flux. On in situ thermal annealing, explosive crystallization occurred preferentially and partially at low temperatures in Ge-rich a-SixGe100-x for x < 50 but not for x > 50. These results indicate that the increase of Si content in a-SiGe prevents the occurrence of explosive crystallization. We previously proposed that explosive crystallization can occur in pristine a-Ge films via the interface of a liquid-like, high-density amorphous state at the growth front. An increase in the instability of this high-density amorphous state caused by the increase of Si in a-SiGe apparently gives rise to the suppression of explosive crystallization.

  • Effects of hydrogen on structure and crystallization behavior of sputter-deposited amorphous germanium films

    Hanya Y., Nakamura R., Okugawa M., Ishimaru M., Oohata G., Yasuda H.

     Japanese Journal of Applied Physics  59 (7)   075506.1 ~ 075506.7  2020年07月

    10.35848/1347-4065/ab9cd9  共著  共同(主担当)

    [概要]

    We examined by transmission electron microscopy the structure and crystallization behavior of hydrogenerated and non-hydrogenerated amorphous germanium films (a-Ge:H and a-Ge) prepared by sputtering to figure out the effects of hydrogen on them. In pair-distribution function, first and second peaks at the interatomic distance of 0.26 and 0.40 nm, respectively, were found to be higher and sharper in a-Ge:H than in a-Ge; therefore amorphous structure was organized in a more ordered state within a short range by hydrogeneration. On thermal annealing, fine nanograins (FGs) of about 10 nm in size appeared preferentially at 350 °C and above in a-Ge:H, which is in contrast with the formation of coarse particles of about 100 nm in size at 500 °C in a-Ge. Hydrogeneration would make a certain number of short-range ordered clusters distributed in the amorphous matrix, inducing the preferential formation of FGs at lower temperatures.

  • 二次イオン質量分析法によるα鉄中のホウ素の拡散浸透プロファイルの測定と拡散係数の決定

    濱名 桂佑 , 仲村 龍介 , 沼倉 宏 , 鈴木 健之

    日本鉄鋼協会  鉄と鋼  106 (6)   302 ~ 309  2020年06月

    10.2355/tetsutohagane.TETSU-2019-104  共著  共同(主担当)

    [概要]

    We report an attempt to determine the diffusion coefficient of B in α Iron by measuring the penetration profile by means of secondary-ion mass spectrometry (SIMS). Pure iron plates of grain-size of 1 to 3 mm were prepared, and thin films of Fe-B alloy (200 nm) and alumina (50 nm) were deposited on the surface as a B source and a capping layer, respectively. The samples were subjected to diffusion annealing at 700ºC, 800ºC, and 900ºC for certain periods of time, and the intensity of secondary ions of B was measured as a function of depth by SIMS. The mesa method was employed, in which a groove is prepared first around the target area by sputtering, and then the depth profile of B through the inner pillar was obtained. The concentration profiles thus obtained were analysed with the thin-film solution, the error-function solution, and also using Hall’s method, depending on the form of the profile. The diffusion coefficient was of the order of 10–18 m2 s–1 in all the cases, which is seven to eight orders of magnitude smaller than those evaluated from deboronising experiments in the 1950 s, but is close to recent theoretical prediction for substitutional diffusion.

  • Liquid-mediated crystallization of amorphous GeSn under electron beam irradiation

    Inenaga K., Motomura R., Ishimaru M., Nakamura R., Yasuda H.

    Journal of Applied Physics  Journal of Applied Physics  127 (20)   205304.1 ~ 205304.9  2020年01月

    10.1063/5.0006416  共著  共同(副担当)

    [概要]

    Crystallization processes of amorphous germanium–tin (GeSn) under low-energy electron-beam irradiation were examined using transmission electron microscopy (TEM). Freestanding amorphous GeSn thin films were irradiated with a 100 keV electron beam at room temperature. The amorphous GeSn was athermally crystallized by electron-beam irradiation, when the electron flux exceeded the critical value. Heterogeneous structures consisting of nano- and micro-crystallites were formed after crystallization of amorphous GeSn with ∼24 at. % Sn in the as-sputtered amorphous state. In situ TEM observations of structural changes under electron-beam irradiation revealed that random nucleation and growth of nanocrystallites occur at the early stage of crystallization, followed by rapid formation of micro-grains surrounding the nanocrystals. It has been suggested that the growth of micro-grains progresses via supercooled liquid Sn at the amorphous/crystalline interface. The resultant GeSn grains with a size of a few micrometers contained ∼15 at. % Sn, much larger than the solubility limit of Sn in Ge (∼1 at. % Sn).

  • Direct observations of crystallization processes of amorphous GeSn during thermal annealing: A temperature window for suppressing Sn segregation

    Higashiyama M., Ishimaru M., Okugawa M., Nakamura R.

     Journal of Applied Physics  125 (17)   175703.1 ~ 175703.8  2019年05月

    10.1063/1.5086480  共著  共同(副担当)

    [概要]

    The solubility limit of tin (Sn) in germanium (Ge) is very small, and, therefore, it is difficult to synthesize high Sn concentration GeSn crystals by conventional methods. An amorphous phase can contain elements beyond the solubility limit of the crystal state, and, therefore, recrystallization of the amorphous alloy is one of the possible ways to realize materials far from the equilibrium state. To suppress Sn precipitation during thermal annealing, knowledge of crystallization processes is required. In the present study, amorphous GeSn thin films with different Sn concentrations were prepared by sputtering, and their crystallization processes were examined by in situ transmission electron microscopy. It was found that the crystallization temperature decreases with increasing Sn concentration, and it became lower than the eutectic temperature when the Sn concentration exceeded ∼25 at. %. Radial distribution function analyses revealed that phase decomposition occurs in the amorphous state of the specimens which crystallize below the eutectic temperature, and Sn crystallites were simultaneously precipitated with crystallization. On the other hand, no remarkable phase decomposition was detected in amorphous GeSn with <25 at. % Sn. Sn precipitation occurred at a higher temperature than the crystallization in these specimens, and the difference between the crystallization and Sn precipitation temperatures became large with decreasing Sn concentration. Because of the existence of this temperature difference, a temperature window for suppressing Sn segregation existed. We demonstrated that large GeSn grains with high Sn concentration could be realized by annealing the specimens within the temperature window.

  • Synthesis of high Sn concentration GeSn by recrystallization of amorphous phase

    Higashiyama M., Ishimaru M., Okugawa M., Nakamura R.

     Materials Science and Technology 2018, MS and T 2018   284 ~ 287  2019年01月

    10.7449/2018/MST_2018_284_287  共著  共同(副担当)

    [概要]

    Amorphous structures of germanium-tin (GeSn) thin films as well as their recrystallization processes during thermal annealing were examined by means of transmission electron microscopy. The specimens were prepared by radio-frequency magnetron sputtering. The as-sputtered GeSn thin films possessed an amorphous structure with 16.4 at.%Sn. The specimen crystallized at 325 °C, and Sn atoms were substitutionally incorporated in a diamond structure. The Sn atoms were ejected from Ge at 350 °C, and molten Sn were formed. In the cooling process, it was confirmed that the molten Sn remained at 150 o C which is much lower than the eutectic temperature of the Ge-Sn binary system. Finally, a remarkable Sn precipitates were formed at room temperature.

  • The relation between amorphous structure and explosive crystallization of sputter-deposited amorphous germanium thin films

    Okugawa M., Nakamura R., Numakura H., Heya A., Matsuo N., Yasuda H.

     Japanese Journal of Applied Physics  58 (4)   045501.1 ~ 045501.6  2019年01月

    10.7567/1347-4065/ab0909  共著  共同(主担当)

    [概要]

    In amorphous germanium (a-Ge) and amorphous silicon films, extremely rapid crystallization, called explosive crystallization, is known to occur by instantaneous processes such as mechanical stimulation, laser irradiation, and electron irradiation. In the present study, using transmission electron microscopy, we have investigated crystallization of a-Ge induced by electron irradiation and flash-lamp annealing (FLA). We have found that the mode of crystallization depends on the amorphous state: explosive crystallization occurred by both electron irradiation and FLA in pristine films, while it did not occur in those aged at room temperature for over 6 months. In a previous paper [Okugawa et al., J. Appl. Phys. 119, 214309 (2016)], it was reported that liquid-like high-density amorphous (HDA) regions were formed in a-Ge films by the long-term aging. The explosive crystallization observed in pristine a-Ge films is suggested to occur via liquid-like HDA interfaces at the growth front.

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著書 【 表示 / 非表示

  • 中空微粒子の合成と応用

    仲村龍介

    シーエムシー出版  2016年11月

    単行本(学術書)  分担執筆

  • Recent Progress in Fabrication of Hollow Nano-structures

    Ryusuke Nakamura, Hideo Nakajima

    Springer  2013年

    単行本(学術書)  分担執筆

  • Recent progress in fabrication of hollow nanostructures

    Nakamura R., Nakajima H.

    Advanced Structured Materials  2012年01月

    単行本(学術書)  単著

  • マクロおよびナノポーラス金属の開発最前線

    仲村龍介

    シーエムシー出版  2011年

    単行本(学術書)  分担執筆

  • Diffusion study in Japan

    仲村龍介

    Research signpost  2006年

    単行本(学術書)  分担執筆

総説・解説記事 【 表示 / 非表示

  • アモルファスGeSnの結晶化におけるSnの振る舞い

    石丸 学 , 仲村 龍介

    日本金属学会  まてりあ  59 (12)   662 ~ 668  2020年12月

    10.2320/materia.59.662  共著  共同(副担当)

  • 低エネルギー電子線照射によるアモルファスGeSnの結晶化

    石丸 学 , 仲村 龍介

     顕微鏡  54 (3)   126 ~ 130  2019年12月

     共著  共同(副担当)

  • 電子励起効果によるアモルファス物質の低温結晶化

    石丸 学 , 仲村龍介

     日本結晶学会誌  61 (1)   29 ~ 34  2019年03月

    10.5940/jcrsj.61.29  共著  共同(副担当)

  • 気相法で作製したアモルファスゲルマニウム薄膜の構造変化と結晶化

    仲村 龍介 , 奥川 将行 , 沼倉 宏

     顕微鏡  52 (3)   166 ~ 169  2017年12月

     共著  共同(主担当)

  • アモルファス酸化物の構造変化および結晶化に伴うナノポーラス化

    仲村 龍介 , 石丸 学 , 平田 秋彦 , 佐藤 和久 , 多根 正和 , 君塚 肇 , 今野 豊彦 , 中嶋 英雄

    日本金属学会  まてりあ  51 (3)   95 ~ 101  2012年03月

    10.2320/materia.51.95  共著  共同(主担当)

  • 金属の酸化反応を利用した酸化物中空ナノ粒子およびナノチューブの作製

    仲村 龍介 , 中嶋 英雄

    アグネ技術センター  金属  80 (9)   757 ~ 762  2010年09月

     共著  共同(主担当)

  • 金属ナノ粒子の酸化による中空構造体の形成

    仲村 龍介 , 床桜 大輔 , 李 正九 , 森 博太郎 , 中嶋 英雄

    日本金属学会  まてりあ  47 (7)   368 ~ 374  2008年07月

    10.2320/materia.47.368  共著  共同(主担当)

  • B2型金属間化合物の拡散 –構造欠陥は拡散に寄与するのか

    仲村龍介

    アグネ技術センター  金属  74 (9)   890 ~ 894  2004年09月

     単著  共同(主担当)

  • NiAl, CoA, FeAlにおける相互拡散とマルチプルマーカー法による固有拡散係数の決定

    山崎 仁丈 , 仲村 龍介 , 高澤 孝一 , 飯島 嘉明

    日本金属学会  まてりあ  39 (6)   497 ~ 501  2000年06月

    10.2320/materia.39.497  単著  共同(副担当)

会議での講演 【 表示 / 非表示

  • Diffusion of boron in alpha-iron: Long-range diffusion measurement by secondary ion mass spectroscopy

    15th International Conference on Diffusion in Solids and Liquids (DSL2019)  2019年06月

  • Structural evolution and crystallization behaviour of sputter-deposited amorphous germanium films

    International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS -Processing, Fabrication, Properties, Applications- (Thermec’2018)  2018年07月

  • アモルファス Ge 薄膜における構造不均一と結晶化挙動

    日本学術振興会 材料の微細組織と機能性第 133委員会 第239回研究会 「半導体材料における結晶欠陥・拡散・薄膜の結晶化挙動」  2018年01月

  • アモルファス Ge 薄膜の結晶化における安定相と準安定相の競合

    第78回 応用物理学会 秋季学術講演会 シンポジウム「IV 族系半導体の製膜と低温結晶化(固相結晶化を中心に)」  2017年09月

  • Inhomogeneous crystallization of sputter-deposited amorphous Ge films

    International workshop on Active-Matrix Flatpanel Display and Devices (AM-FPD 17)  2017年07月

  • 単成分アモルファス物質における構造不均一性と それにまつわる二、三の現象

    日本材料学会 金属ガラス部門委員会 第36 回研究会「ガラス構造と製膜技術」  2016年05月

  • アモルファス酸化物の潜在的欠陥構造に由来するナノポーラス構造の形成

    日本セラミックス協会 第26回秋季シンポジウム  2013年09月

  • 点欠陥の集積化を利用したナノポーラス構造体の作製に関する研究

    日本鉄鋼協会・日本金属学会関西支部 材料開発研究会 平成25年度第1回研究会  2013年05月

 

競争的資金(科学研究費補助金・振興調整費・JSPS等) 【 表示 / 非表示

  • 電子ビームを用いたアモルファスGeSnの室温・瞬間結晶化技術の確立と電気特性評価

     科学研究費助成事業 基盤研究(B)   2022年04月 ~ 2025年03月

  • 銀中の酸素の粒界拡散挙動の解明:ヒロック形成と制御の基礎

     泉科学技術振興財団 2021年度研究助成   2021年10月 ~ 2023年09月

  • 鉄中のホウ素の粒界拡散係数の測定

     日本鉄鋼協会 鉄鋼研究振興助成(第30回)   2021年04月 ~ 2023年03月

  • 非加熱方式によるGeSn混晶薄膜の作製

     村田学術振興財団 第36回(2020年度)研究助成   2020年07月 ~ 2021年06月

  • 鉄中のボロンの“正規の”および“異常な”拡散

    日本学術振興会  科学研究費助成事業 基盤研究(C)   2019年04月 ~ 2022年03月

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