2024/03/15 更新

写真a

トクナガ トモハル
徳永 智春
TOKUNAGA, Tomoharu
所属
大学院工学研究科 材料デザイン工学専攻 先端計測分析 助教
大学院担当
大学院工学研究科
学部担当
工学部 マテリアル工学科
職名
助教
連絡先
メールアドレス

学位 1

  1. 工学博士 ( 2007年9月 ) 

研究分野 4

  1. ナノテク・材料 / ナノ材料科学

  2. ナノテク・材料 / 構造材料、機能材料

  3. ナノテク・材料 / ナノ材料科学

  4. ナノテク・材料 / 構造材料、機能材料

経歴 5

  1. 名古屋大学   大学院工学研究科 材料デザイン工学専攻 先端計測分析   助教

    2017年4月 - 現在

  2. 名古屋大学   大学院工学研究科 量子工学専攻   助教

    2007年10月 - 2017年3月

  3. 名古屋大学 工学研究科 助教

    2007年10月

      詳細を見る

    国名:日本国

  4. 名古屋大学 工学研究科 助教

    2007年10月

  5. 名古屋大学 工学研究科 助教

    2007年10月

学歴 2

  1. 九州大学   工学部   工学府 材料物性工学専攻

    2005年4月 - 2007年9月

      詳細を見る

    国名: 日本国

  2. 名古屋工業大学   工学研究科   都市循環システム工学専攻

    2003年4月 - 2005年3月

      詳細を見る

    国名: 日本国

所属学協会 8

  1. 日本金属学会

  2. フラーレン・ナノチューブ学会

  3. 顕微鏡学会

  4. 応用物理学会

  5. フラーレン・ナノチューブ学会

  6. 応用物理学会

  7. 日本金属学会

  8. 顕微鏡学会

▼全件表示

委員歴 2

  1. 東海若手セラミスト懇話会   運営委員  

    2006年4月 - 現在   

  2. 東海若手セラミスト懇話会   運営委員  

    2006年4月 - 現在   

受賞 1

  1. 第57回金属組織写真賞 奨励賞

    2006年   日本金属学会  

     詳細を見る

    受賞国:日本国

 

論文 137

  1. Non-uniformity of shrinkage rate as a function of current acceleration during flash event under voltage-to-current protocol in 8 mol %Y<sub>2</sub>O<sub>3</sub>-ZrO<sub>2</sub> 査読有り

    Seko, M; Inagaki, S; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   132 巻 ( 3 ) 頁: 93 - 98   2024年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    This study verified the behavior of sample current, volumetric power dissipation, and shrinkage during flash sintering with the voltage-to-current protocol in the time frame of 90 s before and after the flash event. The volumetric power dissipation exhibited a peak value, followed by a decrease to the minimum value, and then increased asymptotically and approached a steady-state value. The discrepancy between the peak and minimum values, ¦P, increased with the limiting current value pre-set at the power supply during the heat-up stage. As ¦P increased, the degree of shrinkage progress decreased in stage III after the flash event, which is caused by the heterogeneity of shrinkage rate inside a compact. To consider the complete shrinkage amount, including stage III, in the current-to-voltage protocol, it is crucial to ensure that ¦P does not reach an excessive level when setting the maximum current.

    DOI: 10.2109/jcersj2.23179

    DOI: 10.2109/jcersj2.23179

    Web of Science

    Scopus

  2. Variation of grain boundary dihedral angles caused by voltage-to-current-based flash treatment in fully stabilized yttria-doped zirconia polycrystals 査読有り

    Seko, M; Kayukawa, S; Inagaki, S; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   132 巻 ( 2 ) 頁: 63 - 67   2024年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    The flash sintering method has garnered attention for its ability to significantly accelerate the densification rate of ceramic green compact through the generation of an electric power spike under an electric field exceeding a defined threshold. In order to amass foundational knowledge about the phenomenon that results from an electric field during flash sintering via a voltage-to-current protocol, the dihedral angles of grain boundaries were surveyed in flash-treated pre-sintered fully stabilized zirconia polycrystal. The flash treatment resulted in a reduction of the grain boundary dihedral angle for grain boundaries that are approximately perpendicular to the direction of the electric field. The reduction in the dihedral angle is possibly attributed to a reduction in surface energy which can be observed through the formation of sinuous pores during flash sintering.

    DOI: 10.2109/jcersj2.23170

    Web of Science

    Scopus

  3. Effect of Initial Grain Size on Crack Healing Behavior under DC Electric Field of Zirconia (8Y-CSZ) Ceramic 査読有り

    Takahashi, S; Morita, K; Nambu, K; Terada, D; Kobayashi, K; Tokunaga, T; Yamamoto, T

    ADVANCED ENGINEERING MATERIALS   25 巻 ( 18 )   2023年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Advanced Engineering Materials  

    The effect of initial grain size on the flash event was examined in microcrack healing behavior under DC electric field in fine- and coarse-grained 8 mol% Y2O3-stabilized cubic ZrO2 (8Y-CSZ) polycrystals. The healing behavior depends strongly on the initial grain size and is apparently accelerated in fine-grained 8Y-CSZ than in coarse-grained one. Since the crack healing under the flash event is higher than that of static annealing treatment without the electric field, the enhanced healing phenomena cannot be explained only by the thermal effect caused by Joule heating, but nonthermal effects caused by the flash event. The grain size-dependent healing behavior indicates that the grain boundaries play an important role in the flash event and the flash healing would be accelerated through the field/current-enhanced diffusional processes, especially through the grain boundary diffusivity of the cations.

    DOI: 10.1002/adem.202201807

    DOI: 10.1002/adem.202201807

    Web of Science

    Scopus

  4. Layer transfer of ultrathin Ge crystal segregated on Al/Ge(111) structure 査読有り

    Matsushita, K; Ohta, A; Shibayama, S; Tokunaga, T; Taoka, N; Makihara, K; Miyazaki, S

    JAPANESE JOURNAL OF APPLIED PHYSICS   62 巻 ( SG )   2023年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Journal of Applied Physics  

    Effects of the surface modification by O2 plasma exposure on the Al/Ge(111) structure have been investigated in order to get an insight into a layer transfer technique of the ultrathin Ge layer segregated on the Al/Ge(111) structure toward the device fabrication, and then the wafer bonding of the Al/Ge(111) structure to the thermally-grown SiO2/Si structure has been demonstrated. The O2 plasma treatment and the subsequent pure water rinse were found to be effective to form the hydrophilic surface of the Al/Ge(111) structure with a suppression of the segregated Ge layer oxidation. The Al/Ge(111) structure with the hydrophilic surface was then bonded to the SiO2/Si substrate, and its bonding strength was enough to perform Ge thinning by the chemical mechanical polishing and the wet-chemical etching using H2O2-based solutions. Ohmic contact of the ring-type device pattern with the segregated Ge/Al stack was achieved by using the remaining p-type Ge substrate as the contact pads.

    DOI: 10.35848/1347-4065/acb65c

    DOI: 10.35848/1347-4065/acb65c

    Web of Science

    Scopus

  5. Scanning electron microscopy observation in wide field of view for SrO/TiO2-terminated step-terrace structure formed on SrTiO3(001) single crystal surface 査読有り

    Katsuyama, Y; Kodaira, A; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   131 巻 ( 5 ) 頁: 135 - 139   2023年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    SrO-terminated terraces were formed along TiO2-terminated step edges by annealing (001) surfaces of SrTiO3 single crystal originally with step-terrace structure fully terminated at TiO2 atomic layer. The prepared step-terrace structure with the two different terminations were visualized in a wide field of view using scanning electron microscopy (SEM) under a low acceleration voltage of 1 kV and a short working distance of 2 mm. The different termination was clearly identified by an in-column secondary electron detector even in the wide-field region with dimensions of 30 © 30 ¯m2. As results, the uniformity of the step-terrace structure was found to be limited only at a localized area. The wide-field observation revealed that there exist many “step-defects” such as pinning of the step lines and wandering so large that it goes around to an opposite side. Step-defects were present in at least several for 30 © 30 ¯m2 sized observation areas with a probability of about 60 %.

    DOI: 10.2109/jcersj2.23011

    DOI: 10.2109/jcersj2.23011

    Web of Science

    Scopus

  6. Local Crystallization of Amorphous Aluminum Oxide Thin Film Using Electron Beam Irradiation by SEM

    Tanahashi, S; Okawara, S; Tokunaga, T; Yamamoto, T

    MATERIALS TRANSACTIONS   64 巻 ( 1 ) 頁: 184 - 190   2023年

  7. Shrinkage-rate controlled flash sintering for 3-10 mol %Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> polycrystals 査読有り

    Koike, M; Kodaira, A; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   130 巻 ( 12 ) 頁: 906 - 912   2022年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    Shrinkage-rate controlled flash (SCF) sintering using alternative current electric field was systematically performed for 310 mol% Y2O3-doped ZrO2. As results, the uniformly densified compacts with about 99% relative densities could be produced at furnace temperatures of about 754781 °C for about 30 min as SCF-regime irrespective of Y concentration, while the achieved densities were limited by conventional flash sintering. The shrinkage-rates during SCF-sintering were found to be enhanced in lower temperature range comparing those during thermal-sintering. The enhancement of shrinkage-rates in lower temperature range observed in SCFsintering is possibly related to the reduction of apparent activation energy of sintering under electric fields.

    DOI: 10.2109/jcersj2.22114

    Web of Science

    Scopus

  8. Shell-like structure to limit further densification formed during flash sintering under alternative current electric field for 8 mol %Y2O3-doped ZrO2 査読有り

    Seko, M; Hattori, K; Ishino, Y; Kodaira, A; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   130 巻 ( 11 ) 頁: 895 - 898   2022年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    A phenomenon often appears that the final achieved density is limited during conventional flash sintering even under alternative current electric field. By observing the cross-sectional microstructure of the flash sintered 8 mol %Y2O3-doped ZrO2 at this state, we found that a thin surface portion with near full density surrounds a porous inside with lower density. The densified thin surface portion is shell-like structure covering a whole of the sintered compact. The formation of this characteristic shell-like structure in the early stage of flash sintering greatly restricts subsequent densification of porous inside. In order to suppress the formation of the shell that inhibit densification, a technique of controlling a steep power spike at a flash event must be necessary to be appropriately transitioned.

    DOI: 10.2109/jcersj2.22109

    Web of Science

    Scopus

  9. A first attempt of automated shrinkage-rate control flash sintering using a current profile without feedback of shrinkage behavior for 8 mol % Y<sub>2</sub>O<sub>3</sub> -doped ZrO<sub>2</sub> 査読有り

    Koike, M; Ishino, Y; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   130 巻 ( 4 ) 頁: 327 - 330   2022年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    Shrinkage-rate control flash (SCF) sintering is an attractive flash sintering that is modified to densify ceramic green compacts up to high density, which controls electric current to keep shrinkage-rate constant by feedback from shrinkage behavior during a flash state. To build up easier sintering protocol and to realize faster shrinkage-rate, we attempted automated SCF-sintering using the predicted current profile without feedback of the shrinkage behavior. As results, 8YSZ polycrystal with a density of 5.83 g/cm3 and a grain size of 1.84.5 μm could be produced within 10 min during SCF and soaking regimes at the furnace temperature of 870 °C, although the linearity of shrinkage-rate during automated SCF-sintering is degraded from the assumed shrinkage-rate. In order to improve automated SCF-sintering further, a more accurate method of approximating the current profile would be necessary to realize the higher linearity of shrinkage-rate.

    DOI: 10.2109/jcersj2.22009

    Web of Science

    Scopus

  10. Crystalline boron monosulfide nanosheets with tunable bandgaps 査読有り

    Kusaka, H; Ishibiki, R; Toyoda, M; Fujita, T; Tokunaga, T; Yamamoto, A; Miyakawa, M; Matsushita, K; Miyazaki, K; Li, LH; Shinde, SL; Lima, MSL; Sakurai, T; Nishibori, E; Masuda, T; Horiba, K; Watanabe, K; Saito, S; Miyauchi, M; Taniguchi, T; Hosono, H; Kondo, T

    JOURNAL OF MATERIALS CHEMISTRY A   9 巻 ( 43 ) 頁: 24631 - 24640   2021年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Materials Chemistry A  

    Two-dimensional (2D) boron monosulfide (BS) nanosheets are predicted to have several stable phases and unique electronic structures, endowing them with interesting attributes, including superconducting, thermoelectric, and hydrogen storage properties. In this paper, we report the experimental realization of 2D BS nanosheets by the physical exfoliation of rhombohedral boron monosulfide (r-BS). Moreover, we demonstrate the facile separation of a mixture of 2D BS nanosheets and the r-BS powder in acetonitrile; the former were selectively separated as a dispersion in the supernatant, whereas the latter remained in the precipitate. In addition, density functional theory calculations reveal a clear dependence of the bandgap energy (Eg) on the number of layers of stacked BS nanosheets, whereEgfor BS nanosheets is approximately 1.0 eV higher than that for r-BS. Atomic force microscopy, cathode luminescence, ultraviolet-visible absorption spectroscopy, and excitation emission matrix experiments revealed a consistent bandgap difference of approximately 1.0 eV between the BS nanosheets and r-BS. We also demonstrate the applications based on the properties that originated from the difference in the bandgap between r-BS and BS nanosheets using photoelectrochemical current switching. These results indicate that the nanosheet bandgap can be tuned to a desired value by controlling the number of stacked 2D BS nanosheets. Therefore, BS nanosheets are promising non-metal 2D materials for applications requiring bandgap control, such as electronics and photocatalysis.

    DOI: 10.1039/d1ta03307g

    Web of Science

    Scopus

  11. Shrinkage rate control during a flash state by current-ramping for 3 mol% Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> polycrystals 査読有り

    Ishino, Y; Taguchi, K; Koike, M; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   104 巻 ( 10 ) 頁: 4960 - 4967   2021年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Ceramic Society  

    3 mol% Y2O3-doped ZrO2 green compacts with rectangular shapes were sintered by maintaining the shrinkage rates at constant values under alternating electric fields by ramping the electric current during flash states. Green compacts were furnace-heated under 40-100 Vrms/cm until current hits an initial current limit of 100 mArms. After then, current-ramping was started to keep the shrinkage rates constant by increasing the limit current value using a programmable power supply operating in a current control mode. Highly densified 3 mol% Y2O3-doped ZrO2 polycrystals with a density of 6.05 g/cm3 as a bulk density and a grain size of about 0.4 μm were obtained at a furnace temperature of about 930℃, 50 Vrms/cm with 1000 Hz and shrinkage rate of about 120 μm/min (0.8%/min against initial lengths of green compacts). The Vickers hardness and indentation fracture toughness of the compact exhibit similar values to those obtained from thermally sintered compacts.

    DOI: 10.1111/jace.17912

    Web of Science

    Scopus

  12. Rapid sintering of 3 mol % Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> by a combined rapid furnace heating and shrinkage-controlled flash sintering protocol 査読有り

    Ishino, Y; Taguchi, K; Kodaira, A; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   129 巻 ( 8 ) 頁: 551 - 554   2021年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    Flash sintering has attracted much attention as a useful sintering technique that is able to lower the sintering furnace temperature and shorten the sintering time. To further improve this original flash sintering technique, we have developed a technique to facilitate shrinkage at a constant shrinkage rate by controlling the power dissipation during a flash state, which is termed as shrinkage-controlled flash (SCF) sintering. Here, we combine this SCF sintering method with a rapid furnace heating process to shorten the entire sintering process time. Accordingly, we succeed in sintering 3 mol % Y2O3-doped ZrO2 (3YSZ) polycrystals with a high density of 6.05 g/cm3 and a uniform grain size of approximately 0.47 μm with a short sintering time of approximately 40 min. The obtained 3YSZ polycrystals are confirmed to exhibit a Vickers hardness and fracture toughness [by an indentation fracture method] of approximately 1295 HV and 5.3 MPa m1/2, respectively.

    DOI: 10.2109/jcersj2.21066

    Web of Science

    Scopus

  13. Near complete densification of flash sintered 8YSZ: controlled shrinkage rate effects 査読有り

    Taguchi, K; Ishino, Y; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   41 巻 ( 8 ) 頁: 4567 - 4571   2021年7月

     詳細を見る

    記述言語:英語   出版者・発行元:Journal of the European Ceramic Society  

    Rate-controlled sintering of 8 mol%Y2O3-doped ZrO2 (8YSZ) polycrystals was performed by rating the current limit of alternating current (AC) electric field during a flash event; this method promotes constant linear shrinkage of the green compact with respect to the sintering time. A power dissipation peak associated with the flash event was suppressed by setting the initial current limit at 100 mA; after AC current hits 100 mA, the current limit was rated to a maximum value of 1100−2000 mA to keep shrinkage rate constant. The power dissipation behavior during the current-rating process exhibited a characteristic inverted S-shaped curve as a function of time. 8YSZ polycrystal with a near-theoretical density of 5.97 g/cm3 and a grain size of approximately 3.4 μm was produced in AC electric field (150 V/cm at 1000 Hz) with a final maximum current limit of 1150 mA as a rectangular bulk style.

    DOI: 10.1016/j.jeurceramsoc.2021.03.005

    Web of Science

    Scopus

  14. Constant shrinkage rate control during a flash event for 8 mol%Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> polycrystals 査読有り

    Taguchi, K; Ishino, Y; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   129 巻 ( 3 ) 頁: 204 - 207   2021年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    The shrinkage rate during a flash event is controlled at a constant value by current ramping for 8 mol %Y2O3ZrO2 green compact with a rectangular shape. The green compact is heated at a constant heating rate of 5 °C/min until the occurrence of a flash event under a constant alternative current (AC) field of 50 Vrms/cm and 1000 Hz at a limit current of 100 mArms. After the flash event, current ramping is started to keep the shrinkage rate at a constant value of 120 ¯m/min. Current ramping is conducted by controlling the limit current using a programmable power supply operating in a current control mode. When the limit current reaches 1200 mArms, the sintering condition is kept as it is for 5 min, and the sintering process is completed. 8 mol %Y2O3ZrO2 sintered polycrystal with a relative density of approximately 99 % and a grain size of about 2.5 ¯m can be obtained at a furnace temperature of 870 °C for a current ramping and soaking regime of approximately 30 min.

    DOI: 10.2109/jcersj2.20192

    Web of Science

    Scopus

  15. Power Dissipation Behaviors during SCF-sintering for 8 mol% Y<inf>2</inf>O<inf>3</inf>-doped ZrO<inf>2</inf>

    Ishino Y., Taguchi K., Kodaira A., Tokunaga T., Yamamoto T.

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   68 巻 ( 11 ) 頁: 482 - 486   2021年

     詳細を見る

    出版者・発行元:Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy  

    Shrinkage behaviors during shrinkage rate-controlled flash (SCF) sintering were investigated for 8 mol% Y2O3–ZrO2 (8YSZ) when shrinkage rates were varied between 60 and 300 μm/min under alternating current fields of 50 Vrms/cm, 1200 mArms, and 1000 Hz at a furnace temperature of approximately 870°C. Volumetric power dissipation and electrical conductivity were shown to exhibit similar dependencies against linear shrinkages even if the shrinkage rates were changed. The 8YSZ polycrystals, with similar microstructure and density, could be produced under all SCF conditions used in this study, which was confirmed as a characteristic feature of SCF sintering. Finally, the 8YSZ polycrystals with a density of 5.91–5.93 g/cm3 and a grain size of 2.2–2.6 μm could be produced with a shrinkage process period of 15–65 min at a furnace temperature of approximately 870°C.

    DOI: 10.2497/jjspm.68.482

    Scopus

  16. Cross-sectional Area Dependency of Shrinkages and Grain Sizes of Flash-sintered 3 mol%Y<inf>2</inf>O<inf>3</inf>–ZrO<inf>2</inf> Polycrystals with a Circular Truncated Cone-shape at High Frequency Alternating Electric Current Fields

    Kurachi T., Kobayashi K., Tokunaga T., Yamamoto T.

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy   68 巻 ( 11 ) 頁: 487 - 493   2021年

     詳細を見る

    出版者・発行元:Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy  

    The uniformity of shrinkages and the distribution of grain sizes were investigated for flash-sintered 3 mol%Y2O3-ZrO2 compacts in direct current and alternating current (AC) electric fields using rectangular-shaped and circular truncated cone-shaped green compacts. The use of a high-frequency AC electric field enough to suppress electrode overvoltage was confirmed to be advantageous for uniform shrinkages, regardless of the shapes of the green compacts. However, the grain size distribution became larger in cone-shaped green compacts, the cross-sectional areas of which varied along the compact. The grain sizes in flashed cone-shaped green compacts were found to exhibit a near linear relation to current density, which provides a means for determining the grain size distribution upon the flash sintering of green compacts with different cross-sectional areas along an electric field.

    DOI: 10.2497/jjspm.68.487

    Scopus

  17. EBV status has prognostic implication among young patients with angioimmunoblastic T-cell lymphoma

    Eladl Ahmed E., Shimada Kazuyuki, Suzuki Yuka, Takahara Taishi, Kato Seiichi, Kohno Kei, Elsayed Ahmed Ali, Wu Chun-Chieh, Tokunaga Takashi, Kinoshita Tomohiro, Sakata-Yanagimoto Mamiko, Nakamura Shigeo, Satou Akira

    CANCER MEDICINE   9 巻 ( 2 ) 頁: 678 - 688   2020年1月

     詳細を見る

    記述言語:日本語   出版者・発行元:Cancer Medicine  

    Epstein-Barr virus (EBV)-positive B cells have been detected in 66%-86% of patients with angioimmunoblastic T-cell lymphoma (AITL). However, it remains controversial whether EBV status has an impact on the survival of patients with AITL. In this study, we aimed to reevaluate the impact of EBV on the clinicopathological characteristics of AITL. In particular, we focused on the impact of EBV in younger patients with AITL. In total, 270 cases of AITL were studied. Epstein-Barr virus-positive B cells were detected in 191 (71%) cases (EBER+ group). Among the patients who received anthracycline-based therapy, the EBER status did not affect the overall survival (OS) or progression-free survival (PFS). In the younger group of AITL (≤60 years), PFS was significantly worse in the EBER− group compared to the EBER+ group (P =.0013). Furthermore, the multivariate analysis identified EBER-negative status, thrombocytopenia, and elevated serum IgA level as significant adverse prognostic factors for PFS (P <.001, P <.001, and P =.002). Based on these findings, we constructed new prognostic model for the younger group, based on three adverse factors. We classified the patients into two risk groups: low risk (no or 1 adverse factor) and high risk (2 or 3 adverse factors). This new model for younger patients with AITL showed that both OS and PFS were significantly related to the level of risk (P <.0001). In summary, this study showed that, among younger patients with AITL, an EBER+ status significantly improved prognosis compared to an EBER− status. Our new prognostic model should be applicable to younger patients with AITL.

    DOI: 10.1002/cam4.2742

    Web of Science

    Scopus

  18. Characterisation of bovine embryos following prolonged culture in embryonic stem cell medium containing leukaemia inhibitory factor

    Hosoe Misa, Furusawa Tadashi, Hayashi Ken-Go, Takahashi Toru, Hashiyada Yutaka, Kizaki Keiichiro, Hashizume Kazuyoshi, Tokunaga Tomoyuki, Matsuyama Shuichi, Sakumoto Ryosuke

    REPRODUCTION FERTILITY AND DEVELOPMENT   31 巻 ( 6 ) 頁: 1157 - 1165   2019年5月

     詳細を見る

    記述言語:日本語   出版者・発行元:Reproduction, Fertility and Development  

    In order to help elucidate the process of epiblast and trophoblast cell differentiation in bovine embryos in vitro, we attempted to develop a suitable culture medium to allow extended embryo culture. Day 7 bovine blastocysts developed in conventional medium were cultured further in embryonic stem cell medium with or without leukaemia inhibitory factor (LIF) until Day 23. At Day 14, the expression of octamer-binding transcription factor 3/4 (OCT3/4) and VIMENTIN was significantly higher in embryos cultured with than without LIF, but embryonic disc formation was not observed. Although expression of SRY (sex determining region Y)-box 17 (SOX17) mRNA was significantly lower in Day 14 embryos cultured with and without LIF than in in vivo embryos, hypoblast cells formed just inside the trophoblast cells of the in vitro-cultured embryos. On Day 23, expression of placental lactogen (PL) and prolactin-related protein 1 (PRP1) was not affected by LIF in in vitro-cultured embryos, levels of both genes were significantly lower in the in vitro than in vivo embryos. Similar to in vivo embryos, binucleate cell clusters seen in Day 23 in vitro-cultured embryos were composed of PL-negative and -positive cells. These results suggest that our culture system partially reproduced the differentiation process of trophoblast cells in vivo.

    DOI: 10.1071/RD18343

    Web of Science

    Scopus

  19. Removal of carbon contamination in ETEM by introducing Ar during electron beam irradiation

    Tokunaga, T; Saito, K; Kuno, K; Higuchi, K; Yamamoto, Y; Yamamoto, T

    JOURNAL OF MICROSCOPY   273 巻 ( 1 ) 頁: 46 - 52   2019年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Microscopy  

    Organic materials, including carbon, exist inside the transmission electron microscope (TEM) chamber and are adsorbed onto samples under observation during TEM. When these adsorbed organic materials are irradiated by an electron beam, the adsorbed gas is decomposed. Carbon atoms remain on the sample and bond with each other forming a material with an amorphous structure. Due to the carbon deposition on the observation area of the sample, it is contaminated and the TEM image quality is decreased. Ar was introduced into environmental TEM (ETEM) to purge organic material from the sample chamber to reduce contamination growth. After Ar gas was introduced, the contamination was gradually removed. The contamination removal rate was dependent on the Ar pressure. Moreover, it was clear that Ar was ionised by electron beam irradiation and the Ar ions were produced in the ETEM during electron beam irradiation. It is proposed that the Ar ions removed the carbon contamination. Lay Description: Organic materials, including carbon, exist inside the transmission electron microscope (TEM) chamber and are adsorbed onto samples under observation during TEM. When these adsorbed organic materials are irradiated by an electron beam, the adsorbed gas is decomposed. Carbon atoms remain on the sample and bond with each other forming a material with an amorphous structure. Due to the carbon deposition on the observation area of the sample, it is contaminated and the TEM image quality is decreased. Ar was introduced into environmental TEM (ETEM) to purge organic material from the sample chamber to reduce contamination growth. After Ar gas was introduced, the contamination was gradually removed. The contamination removal rate was dependent on the Ar pressure. Moreover, it was clear that Ar was ionised by electron beam irradiation and the Ar ions were produced in the ETEM during electron beam irradiation. It is proposed that the Ar ions removed the carbon contamination.

    DOI: 10.1111/jmi.12759

    Web of Science

    Scopus

    PubMed

  20. Intentionally encapsulated metal alloys within vertically aligned multi-walled carbon nanotube array via chemical vapor deposition technique

    Inoue H., Nishikawa T., Hayashi Y., Hada M., Tokunaga T., Amaratunga G., Amaratunga G.

    Conference Program Digest - 7th International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale, IEEE 3M-NANO 2017   2018-January 巻   頁: 357 - 361   2018年2月

     詳細を見る

    記述言語:日本語   出版者・発行元:Conference Program Digest - 7th International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale, IEEE 3M-NANO 2017  

    This paper presents a growth and characterization of vertically aligned PdxCoi-x alloy encapsulated inside Multi-Walled Carbon Nanotube (MWCNT) arrays on Pd/Co thin layers coated on Si substrate by a dc bias-enhanced plasma chemical vapor deposition (CVD) method. The Metal Alloy Encapsulated within MWCNTs (MAE-MWCNTs) were characterized by a scanning electron microscope (SEM) and a transmission electron microscopy (TEM). The SEM images show the teardrop-shape particles encapsulated within the tube top of MWCNTs. A vibrating sample magnetometer was used to study the magnetism of a large number of MAE-MWCNTs on Si substrate at room temperature. The hysteresis loop of the ME-MWCNTs shows clear ferromagnetic behavior and the easy axis of magnetization is parallel to the MEA-MWCNT tube axis, as can be elucidated from the large coercive fields and remanence values. Moreover, TEM off-axis electron holograms were used to study the magnetism of the individual MAE-MWCNT or the two pair of MAE-MWCNTs. Based on electron holography, we have successfully obtained the saturation magnetization of 0.7 T and 1.12 T for the individual MAE-MWCNT with diameters of 41 nm and 83 nm, respectively.

    DOI: 10.1109/3M-NANO.2017.8286262

    Scopus

  21. Applying an alternating current to strontium titanate minimizes the change in oxidation state caused by flash sintering

    Seko, M; Inagaki, S; Tokunaga, T; Kobayashi, S; Nakamura, A; Yamamoto, T

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   44 巻 ( 5 ) 頁: 2965 - 2971   2024年5月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the European Ceramic Society  

    This study estimated the amount of oxygen deficiency in SrTiO3 polycrystals that were flash sintered under direct current (DC) and alternating current (AC) electric fields, mainly by using the fine structural change of the Ti L23-edges collected by electron energy-loss spectroscopy. The DC electric field corresponded to formation of the maximum amount of oxygen deficiency at approximately δ = 0.07 as SrTiO3−δ, which corresponds to a lattice expansion of roughly 0.1% as a lattice constant of SrTiO3. Furthermore, the oxygen deficiency was distributed unevenly. The formation of dislocation networks in DC-flash-sintered SrTiO3 polycrystals might be related to the lattice strain field caused by this nonuniform oxygen deficiency. In contrast, an AC electric field did not correspond to the oxygen deficiency of SrTiO3, which is similar to the results in thermally sintered SrTiO3 polycrystals.

    DOI: 10.1016/j.jeurceramsoc.2023.12.046

    Web of Science

    Scopus

  22. Flash healing of Vickers microcracks formed on the (001) surface of cubic zirconia single crystals

    Kayukawa, S; Katsuyama, Y; Kodaira, A; Tokunaga, T; Morita, K; Nakamura, A; Yamamoto, T

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   43 巻 ( 14 ) 頁: 6272 - 6278   2023年11月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the European Ceramic Society  

    Flash healing, a technique for microcrack healing using a flash event, has recently attracted attention for effective microcrack healing of ceramics. To investigate the diffusion-accelerated phenomena that occur during flash healing, the flash-healing behavior of Vickers indentation microcracks on (001) zirconia single crystals was investigated, mainly from the viewpoint of microstructure analysis of the healed microcracks. Scanning electron microscopy and atomic force microscopy showed that the surface microcracks were rapidly healed. However, scanning transmission electron microscopy showed that a row of pores remained along the original microcrack inside the crystal, and the crystallographic orientation relationship on both sides of the microcrack was restored to that of the original single crystal. Compared with the findings for healing without an electric field, the distance from the pore closest to the surface was larger and the total pore volume was smaller for flash healing. These results suggest that flash treatment increases lattice diffusion.

    DOI: 10.1016/j.jeurceramsoc.2023.06.001

    Web of Science

    Scopus

  23. Near-full compaction within only 30 min of total sintering time by shrinkage-rate-controlled flash sintering in 3 mol % Y2O3-doped ZrO2 polycrystal

    Ishino, Y; Koike, M; Kodaira, A; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   131 巻 ( 10 ) 頁: 600 - 607   2023年10月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    The development of a high-speed sintering method that can shorten the entire sintering time while guaranteeing the mechanical properties is very attractive as a sintering process for structural ceramic polycrystals. For this purpose, a sintering protocol that combines shrinkage-rate-controlled flash sintering, which controls the shrinkage rate to be constant with the use of an alternative current electric field, and a rapid furnace ramp were applied to 3-mol % Y2O3-doped ZrO2 (3YSZ). As a result, a 3YSZ sintered polycrystal with about the relative density of 99.5 % (6.06 g/cm3) could be successfully fabricated within 30 min as the entire sintering time, which includes the furnace-heating regime. The sintered 3YSZ polycrystal is confirmed to exhibit a Vickers hardness of approximately 1290 HV and a fracture toughness (KIC) of approximately 5.2 MPa m1/2, which are similar values to those obtained from a typical thermally sintered 3YSZ polycrystal.

    DOI: 10.2109/jcersj2.23041

    Web of Science

    Scopus

  24. Structural Defect Effect on the Concentration Quenching of TbXY2-XO3 Phosphor Thin Films

    Suzuki, S; Dazai, T; Tokunaga, T; Yamamoto, T; Katoh, R; Takahashi, R

    JOURNAL OF PHYSICAL CHEMISTRY C   127 巻 ( 19 ) 頁: 9380 - 9387   2023年5月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Physical Chemistry C  

    This study investigates the structural defect effect on the luminescence properties of TbxY2-xO3 (x = 0-0.5) composition-gradient films using combinatorial pulsed laser deposition (PLD). TbxY2-xO3 films were grown on a SrTiO3 (001) substrate in an O2/He mixed atmosphere at PO2 = 1 × 10-4 Torr. A He buffer gas moderated the kinetic energy of the PLD plume and suppressed the resputtering of the film surface, resulting in the fabrication of defect-rich and poor TbxY2-xO3 films. The TbxY2-xO3 composition-gradient films exhibited varying green emissions from the Tb-doped Y2O3 films. The luminescence intensity of the defect-rich film was significantly weaker than that of the defect-poor film. Furthermore, concentration quenching of the luminescence occurred at high Tb concentrations. The analysis of the decay profiles of the luminescence as a function of the Tb concentration suggested two possible reasons for luminescence quenching: dynamic quenching induced by structural defects and static quenching induced by the shorter average distance of adjacent Tb ions. The investigation of the structural defect effect on the luminescence properties provides insights into the primary material parameters of phosphor materials and offers a pathway for enhancing their luminescence properties.

    DOI: 10.1021/acs.jpcc.3c01679

    Web of Science

    Scopus

  25. Mechanistic consideration of ZnTe microspheres formation in a PVP-contained polyol system via hot injection method

    Chau, YTR; Nguyen, MT; Tokunaga, T; Yonezawa, T

    ADVANCED POWDER TECHNOLOGY   34 巻 ( 4 ) 頁: 103970 - 103970   2023年4月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Advanced Powder Technology  

    Zinc telluride (ZnTe) microspheres have been synthesized in a polyol system with adding various amount of poly(N-vinyl-2-pyrrolidone) (PVP, K-90) at 200 °C via a hot injection method. The smallest sized ZnTe microspheres obtained in this study had an average size of 634 nm through reaction for 48 h using 518 mg of PVP. A retrospective study was conducted to evaluate the formation process of ZnTe microspheres by conducting experiments from 0.2 h to 48 h. Nucleation and growth of ZnTe at the tips of Te rods in a PVP-contained polyol system were observed in sample reacted less than 1 h. More ZnTe microspheres and less Te rods were observed when the reaction was proceeded for longer time, suggesting that Te rods were the sacrificial template for the growth of ZnTe. Amount of PVP is the key factor of controlling dimensions of Te rods formed at the initial stage as well as the sizes of ZnTe microspheres by influencing the nucleation and growth rate of ZnTe. The obtained ZnTe microspheres at 48 h consisted of voids, which were originated by the detachment of ZnTe microspheres from Te rods after their growth.

    DOI: 10.1016/j.apt.2023.103970

    Web of Science

    Scopus

  26. Flash self-joining of Y-TZP ceramics assisted with an AC electric field 査読有り

    Nambu, K; Kitaoka, T; Morita, K; Soga, K; Tokunaga, T; Yamamoto, T; Masuda, H; Yoshida, H

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   106 巻 ( 3 ) 頁: 2073 - 2082   2023年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Ceramic Society  

    In this study, flash joining experiments were conducted using an AC field on 3 mol% Y2O3‐stabilized tetragonal ZrO2 polycrystal (Y‐TZP) bodies. Furthermore, the necessary conditions to obtain an almost complete self‐joining of Y‐TZP bodies were clarified. The specimens were successfully joined by applying an AC field at 60 mA·mm−2 for 80 s at a furnace temperature of 1000°C, thus resulting in a successfully joined specimen with 92% of the flexural strength of the as‐sintered Y‐TZP body. Almost complete self‐joining of Y‐TZP was achieved at current densities above 30 mA·mm−2, and input energy densities of >24 J·mm−3. Both the input energy density and electric current were critical factors for producing the reliable joining of ceramics.

    DOI: 10.1111/jace.18889

    Web of Science

    Scopus

  27. Microcrack healing in single-crystal cubic zirconia by thermal annealing 査読有り

    Kayukawa, S; Katsuyama, Y; Kodaira, A; Tokunaga, T; Morita, K; Nakamura, A; Higuchi, K; Yamamoto, T

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   43 巻 ( 3 ) 頁: 1078 - 1086   2023年3月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the European Ceramic Society  

    Thermally healed Vickers microcracks perpendicular to (001) surface of cubic zirconia single crystals were investigated mainly with scanning transmission electron microscopy. The orientational relationship of areas containing healed microcracks was completely restored to that of the original single crystal, but a row of pores corresponding to the unhealed state remained where the original microcrack was located. Isolated pore formation proceeded from dislocation recovery via heat treatment, which brought the inner surfaces of the microcrack into contact, followed by diffusion bonding via surface diffusion. Once isolated pores were formed, the total pore volume did not significantly change by increasing the healing temperature, although pore sizes increased and the number of pores decreased. Ostwald ripening became pronounced in pore microstructure evolution when pore elimination was dominated by lattice diffusion after complete crystallographic restoration to a single crystal.

    DOI: 10.1016/j.jeurceramsoc.2022.10.065

    Web of Science

    Scopus

  28. A technique to modify the photoluminescence intensity of β-Ga<sub>2</sub>O<sub>3</sub> polycrystals using an electric field during sintering 査読有り

    Ono, R; Kodaira, A; Tokunaga, T; Yoshida, H; Yamamoto, T

    JOURNAL OF LUMINESCENCE   254 巻   頁: 119508 - 119508   2023年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Luminescence  

    Beta gallium trioxide (β-Ga2O3) is an attractive wide bandgap oxide that exhibits photoluminescent emission in the ultraviolet and blue/green regions. In the present study, we describe the tuning and enhancement of photoluminescent emission in the blue/green region by applying an instantaneous electric field during the sintering of a β-Ga2O3 green compact. Blue/green emission at around 480 nm increases by a factor of approximately 16 in β-Ga2O3 polycrystal prepared with the sintering protocol that a green compact was heated up to 1300 °C and an alternating current electric field (50 V/cm at 1000 Hz) was isothermally loaded. Considering that the enhancement occurs at the cathode side under a direct current electric field, the enhanced blue/green photoluminescence is likely due to an increase in the number of oxygen vacancies.

    DOI: 10.1016/j.jlumin.2022.119508

    Web of Science

    Scopus

  29. Local Crystallization of Amorphous Aluminum Oxide Thin Film Using Electron Beam Irradiation by SEM

    Tanahashi S., Okawara S., Tokunaga T., Yamamoto T.

    Materials Transactions   64 巻 ( 1 ) 頁: 184 - 190   2023年1月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Materials Transactions  

    Amorphous thin film thinned for transmission electron microscopy observation is reported to crystallize by electron beam (EB) irradiation of TEM. If thin film deposited on substrates can be crystallized by EB irradiation of scanning electron microscopy (SEM), new nanoscale devices can be fabricated such as electronic nanoscale circuits in amorphous thin films. Therefore, an amorphous AlOx (am-AlOx) thin film is deposited onto a Si substrate by atomic layer deposition (ALD) and point and area scan irradiation of EBs were performed by SEM. Then, structure and elemental analyses are carried out by TEM. Only the point EB irradiated area crystallized from the surface to the interface between am-AlOx and the Si substrate, and £-Al2O3 appeared. Moreover, the oxygen content of the not irradiated area close to the irradiated area was lower than that of the not irradiated area far from the irradiated area. These results show that the EB irradiated area was positively charged by the emission of secondary and Auger electrons under point irradiation conditions, and that oxygen was supplied by attracting its negative charge to the EB irradiated area. Also, the electrostatic repulsion between positively charged atoms and the structure relaxation due to electron excitation were additional driving forces for the crystallization.

    DOI: 10.2320/matertrans.mt-n2022004

    Scopus

  30. Apparent Sintering Activation Energy Estimated by Master Sintering Curves for 8 mol% Y<inf>2</inf>O<inf>3</inf> Doped ZrO<inf>2</inf> Polycrystals during Shrinkage-Rate Controlled Flash Sintering

    Koike M., Kodaira A., Tokunaga T., Yamamoto T.

    Materials Transactions   64 巻 ( 10 ) 頁: 2315 - 2320   2023年

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Materials Transactions  

    The apparent activation energy of sintering for 8-mol%-Y2O3-doped ZrO2 during shrinkage-rate-controlled flash sintering was determined using a master sintering curve. The activation energy during SCF sintering was found to decrease from approximately 700 to 430 kJ/mol with density. The activation energy in a high-density region is approximately similar value of lattice diffusion, 460 kJ/mol. The relative density range over which the decrease in activation energy occurred during SCF sintering was smaller than during thermal sintering and further moved to a lower temperature range. The increase in shrinkage rate at lower temperatures that occurs during SCF sintering could be considered to be related to this decrease in activation energy.

    DOI: 10.2320/matertrans.MT-T2023002

    Scopus

  31. Apparent Sintering Activation Energy Estimated by Master Sintering Curves for 8mol% Y2O3 Doped ZrO2 Polycrystals during Shrinkage-Rate Controlled Flash Sintering

    Koike, M; Kodaira, A; Tokunaga, T; Yamamoto, T

    MATERIALS TRANSACTIONS   64 巻 ( 9 ) 頁: 2315 - 2320   2023年

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    DOI: 10.2320/matertrans.MT-M2023048

    Web of Science

  32. Variation of photoluminescence intensity depending on the timing of electric field application during isothermal flash sintering for 3mol% Y<sub>2</sub>O<sub>3</sub>-ZrO<sub>2</sub> polycrystal 査読有り

    Itoh, A; Tokunaga, T; Kodaira, A; Yoshida, H; Yamamoto, T

    CERAMICS INTERNATIONAL   48 巻 ( 19 ) 頁: 28712 - 28717   2022年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Ceramics International  

    The shrinkage process and the change in photoluminescence (PL) intensity during isothermal flash sintering were investigated for 3 mol% Y2O3–ZrO2 (3YSZ) polycrystals doped with 300 ppm Bi2O3 as a PL impurity centre. The PL intensity of 3YSZ is enhanced by isothermal flash sintering. However, the enhancement of the PL intensity was revealed to become smaller when flash-treatment was applied for thermally pre-sintered 3YSZ polycrystal. To maximize the efficiency of electric field on the enhancement of the PL intensity, the electric field needs to be applied throughout the sintering from the initial stage to the final densification. The necessity for continuing to apply the electric field until the densification is completed is due to the fact that the recovery of oxygen vacancies, the origin of the F+ band, must be suppressed.

    DOI: 10.1016/j.ceramint.2022.06.185

    Web of Science

    Scopus

  33. Effect of He Buffer Gas on Pulsed Nd:YAG Laser Deposition of Eu<i><sub>x</sub></i>Y<sub>2-<i>x</i></sub>O<sub>3</sub> Phosphor Thin Films 査読有り

    Suzuki, S; Dazai, T; Kawashima, K; Tokunaga, T; Yamamoto, T; Takahashi, R

    ACS APPLIED ELECTRONIC MATERIALS   4 巻 ( 9 ) 頁: 4419 - 4426   2022年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Applied Electronic Materials  

    We investigated the feasibility of using He buffer gas to moderate the kinetic energy of pulsed laser deposition (PLD) plumes during the growth of EuxY2-xO3phosphor films. The PLD growth of Y2O3films using a Nd yttrium aluminum garnet (Nd:YAG) laser results in expanded lattice parameters compared to those of the bulk crystals, indicating the presence of crystal defects in the Y2O3films. Ablation plumes with a high kinetic energy are generated by the Nd:YAG laser that operates at high energy densities, leading to defect formation. To moderate the kinetic energy without reducing the film growth rate, He buffer gas was used for the Nd:YAG-PLD growth of Y2O3films, resulting in the suppression of crystal defect generation. This process was demonstrated to improve the phosphor properties of EuxY2-xO3thin films grown via combinatorial PLD as the He buffer gas-induced reduction in crystal defect density enhances the phosphor properties of the EuxY2-xO3films. Using He buffer gas to moderate the kinetic energy of PLD plumes is expected to be useful in reducing the crystal defect density and improving the film characteristics.

    DOI: 10.1021/acsaelm.2c00691

    Web of Science

    Scopus

  34. A liquid metal catalyst for the conversion of ethanol into graphitic carbon layers under an ultrasonic cavitation field

    Kawasaki, H; Otsuki, T; Sugino, F; Yamamoto, K; Tokunaga, T; Tokura, R; Yonezawa, T

    CHEMICAL COMMUNICATIONS   58 巻 ( 56 ) 頁: 7741 - 7744   2022年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Communications  

    Eutectic gallium indium (EGaIn) has drawn considerable research interest in potential liquid catalysis. Herein, we report that EGaIn liquid metal acts as a catalyst for the growth of a graphitic carbon layer from ethanol under ultrasonication. High-speed imaging demonstrated the formation of ultrasonic cavitation bubbles at the liquid metal/ethanol interface, which facilitated the pyrolysis of ethanol into graphitic carbon on the liquid metal surface.

    DOI: 10.1039/d2cc02510h

    Web of Science

    Scopus

    PubMed

  35. Effect of electron beam irradiation in gas atmosphere during ETEM 査読有り

    Tokunaga, T; Kawakami, T; Higuchi, K; Yamamoto, Y; Yamamoto, T

    MICRON   158 巻   頁: 103289 - 103289   2022年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Micron  

    Transmission electron microscopy (TEM) is used to observe the atomic structures of materials. Environmental TEM (ETEM) is a method wherein a gas can be evaluated and it has been used to observe the dynamic reaction between materials and gases at the atomic level. An electron beam (EB), which has a sufficiently high energy (exceeding a few tens of kilovolts), can be used to ionize gas molecules. Subsequently, the ionized molecules might react with the materials during ETEM. Therefore, the current generated by the ions and electrons were measured to verify the presence of ions generated due to the ionization of the N2 gas atmosphere during EB irradiation in ETEM. The electron energy loss spectra (EELS) were acquired from the N2 gas atmosphere to estimate the types of ions generated. The results demonstrated that ions and electrons were generated in the N2 atmosphere during ETEM and EB irradiation. Moreover, the EELS analysis indicated that the generated ion was N2+. The material observation conducted using gas ETEM can detect the reaction between gases, ions, and materials.

    DOI: 10.1016/j.micron.2022.103289

    Web of Science

    Scopus

    PubMed

  36. The role of surface oxides and stabilising carboxylic acids of copper nanoparticles during low-temperature sintering

    Tokura, R; Tsukamoto, H; Tokunaga, T; Nguyen, MT; Yonezawa, T

    MATERIALS ADVANCES   3 巻 ( 12 ) 頁: 4802 - 4812   2022年6月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Materials Advances  

    This article provides a detailed discussion of 1-hexanoic-acid-stabilised copper nanoparticles with an average diameter of ∼80 nm prepared from cupric oxide micro-powders for low-temperature sintering applications. The obtained fine particles were dispersed in dipropylene glycol using a bead mill to obtain a stable paste containing 50 wt% copper. Sintering experiments at temperatures in the range of 120-250 °C were performed under a nitrogen or 3%H2-N2 gas flow. The lowest resistivity, approximately three times that of bulk copper, was obtained at 250 °C. These particles exhibited good conductivity upon sintering under nitrogen only. 1-Hexanoic acid contributed to the acceleration of sintering by removing the Cu64O oxide layer of the particles and activating the surface. The dispersed copper paste and the copper layer after sintering were observed using SEM.

    DOI: 10.1039/d1ma01242h

    Web of Science

    Scopus

  37. Excess oxygen-vacancy formed by FAST regime of direct-current electric field during flash sintering for 3 mol%-10 mol% Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> 査読有り

    Morisaki, N; Tokunaga, T; Kobayashi, K; Kodaira, A; Yamamoto, T

    CERAMICS INTERNATIONAL   48 巻 ( 9 ) 頁: 12091 - 12097   2022年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Ceramics International  

    The amount of excess oxygen vacancies that are generated during FAST regime of direct-current flash sintering was estimated semi-quantitatively for 3 mol%–10 mol% Y2O3-doped ZrO2 (3–10YSZ) using the temperature dependence of the electrical conductivity. For the estimation, the electrical conductivity in the temperature range, where shrinkages are below a few percent, was used to avoid the effect of large microstructural changes on the electric conductivity. For all Y2O3 contents except 3YSZ, the amount of excess oxygen vacancies increased above a compact temperature of approximately 840 °C, which depended on Y2O3 content, and was highest in 8YSZ. Approximately 0.13% excess oxygen vacancy was generated by direct-current flashing in 8YSZ in the present electric field condition. In contrast, the increase in the excess oxygen vacancies is negligible in 3YSZ. The dependence of the amount of excess oxygen vacancies on the Y2O3 content was related possibly to the dependence of the electrode overvoltage on the Y2O3 content.

    DOI: 10.1016/j.ceramint.2022.01.069

    Web of Science

    Scopus

  38. Anelasticityinduced by AC flash processing of cubic zirconia 査読有り

    Masuda, H; Morita, K; Tokunaga, T; Yamamoto, T; Yoshida, H

    ACTA MATERIALIA   227 巻   頁: 117704 - 117704   2022年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Acta Materialia  

    The defect physics is important for understanding the athermal effect of electric fields and/or currents on the enhanced ionic diffusion during flash sintering of ceramics. In this study, conventionally sintered 8 mol% yttria-stabilized zirconia with a fluorite cubic structure was processed by AC flash and subsequently quenched to partially freeze the flash-induced defect structures. The dynamic and quasi-static mechanical properties of flashed and non-flashed samples were evaluated by a sound velocity measurement and a nanoindentation technique to characterize the mechanical responses attributed to the flash-induced defects. A negligible change was confirmed in the dynamic elastic constants even after flash, while the quasi-static elastic properties of the flashed sample exhibited a considerable rate dependence (i.e., the slower the loading rate, the lower the measured contact modulus). The contact modulus of the flashed sample tested at the slowest loading rate in this study was reduced to approximately 72% of the non-flashed one, where the contact modulus was rate-independent. The time-dependent mechanical behavior was also confirmed during nanoindentation creep. Such rate- and time-dependent mechanical properties are characterized as anelasticity (i.e., viscoelasticity or pseudoelasticity in other terms), which can be attributed to stress-induced and thermally activated recoverable motions of point defects. The flash process of cubic zirconia possibly induced point defects associated with short-range structural change, which could be the origin of anelasticity.

    DOI: 10.1016/j.actamat.2022.117704

    Web of Science

    Scopus

  39. Anisotropic Growth of Copper Nanorods Mediated by Cl<SUP>-</SUP> Ions 査読有り 国際共著

    Saw, MJ; Nguyen, MT; Kunisada, Y; Tokunaga, T; Yonezawa, T

    ACS OMEGA   7 巻 ( 8 ) 頁: 7414 - 7420   2022年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    Anisotropic growth to form Cu particles of rod and wire shapes has been obtained typically in a complex system that involves both organic capping agents and Cl- ions. However, the sole effect of Cl- ions on the formation of Cu wires has yet to be fully understood, especially in an organic system. This present work determines the effect of Cl- ions on the morphologies of Cu particles in an organic phase without any capping agents. The results revealed that anisotropic Cu rods could be grown with the sole presence of Cl- ions. The rods have the (011) facets as the long axis, the (111) facets as the tip, and the (100) facets as the side surface. By increasing the Cl- ion concentration, more Cu atoms contributed to the formation of Cu rods and the kinetic growth of the length and the diameter of the rods varied. This suggests that Cl- ions have preferential adsorption on the (100) Cu surfaces to promote the anisotropic growth of Cu. Meanwhile, the adsorption of Cl- to the (111) and (100) surfaces at high Cl- concentrations regulates the relative growth of the particle length and diameter.

    DOI: 10.1021/acsomega.2c00359

    Web of Science

    Scopus

    PubMed

  40. Direct determination of a topmost atomic layer of (100) surfaces on (La<sub>0.3</sub>Sr<sub>0.7</sub>)(Al<sub>0.65</sub>Ta<sub>0.35</sub>)O<sub>3</sub> single crystals annealed in air by high-resolution scanning transmission electron microscopy 査読有り

    Tokuda, Y; Irimoto, T; Nishikawa, N; Katsuyama, Y; Kobayashi, S; Tokunaga, T; Yamamoto, T

    SURFACE AND INTERFACE ANALYSIS   54 巻 ( 3 ) 頁: 212 - 217   2022年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    Herein, we investigated the surface of an (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) single crystal via scanning transmission electron microscopy (STEM) after annealing in air. We found amorphous mounds and atomically flat surfaces formed on the surface of the (100) LSAT single crystal subsequent to heat treatment. These surface mounds mainly constituted SrO, including ~50 at.% Al. The atomically flat surface showed a B-site termination determined by the direct surface observation at the atomic scale through HAADF-STEM. The atomic arrangements on the surface were accommodated by surface-mound formation and La evaporation. Consequently, the ordered structure disappeared because of the increase in the Ta content at the terminated B-site layer.

    DOI: 10.1002/sia.7043

    Web of Science

    Scopus

    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/sia.7043

  41. Alginate-Stabilized Gold Nanoparticles Prepared Using the Microwave-Induced Plasma-in-Liquid Process with Long-Term Storage Stability for Potential Biomedical Applications 査読有り

    Liu, HR; Ikeda, K; Nguyen, MT; Sato, S; Matsuda, N; Tsukamoto, H; Tokunaga, T; Yonezawa, T

    ACS OMEGA   7 巻 ( 7 ) 頁: 6238 - 6247   2022年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    A one-step preparation of alginate-stabilized gold nanoparticles (Au NPs) using the microwave-induced plasma-in-liquid process (MWPLP) was reported. Effects of alginate with various concentrations on the preparation and properties of the synthesized Au NPs, including reaction rate, morphology, size, and optical absorption property, were studied. The introduction of alginate (1) accelerated the reaction rate, (2) prevented aggregation and precipitation due to long time discharge in MWPLP, and (3) provided long-term colloidal stability. An abnormal size change (from large to small) of Au NPs during particle growth, which was opposite to the typical change in bottom-up chemical reduction, was observed and a possible mechanism was proposed based on the dynamical and thermodynamical instability of particles during growth. The strategy of drying and redispersion of Au NPs in alginate solution was also studied. The drying and redispersion process had an imperceptible effect on the Au NPs. As a consequence, this strategy might be an effective technique for the long-term storage of Au NPs and other metal NPs. The alginate-stabilized Au NPs without the addition of toxic reducing or stabilizing agents can be appropriate to biomedical applications.

    DOI: 10.1021/acsomega.1c06769

    Web of Science

    Scopus

    PubMed

  42. Nanoporous ultra-high-entropy alloys containing fourteen elements for water splitting electrocatalysis

    Cai, ZX; Goou, H; Ito, Y; Tokunaga, T; Miyauchi, M; Abe, H; Fujita, T

    CHEMICAL SCIENCE   12 巻 ( 34 ) 頁: 11306 - 11315   2021年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Science  

    High-entropy alloys (HEAs) are near-equimolar alloys comprising five or more elements. In recent years, catalysis using HEAs has attracted considerable attention across various fields. Herein, we demonstrate the facile synthesis of nanoporous ultra-high-entropy alloys (np-UHEAs) with hierarchical porosityviadealloying. These np-UHEAs contain up to 14 elements, namely, Al, Ag, Au, Co, Cu, Fe, Ir, Mo, Ni, Pd, Pt, Rh, Ru, and Ti. Furthermore, they exhibit high catalytic activities and electrochemical stabilities in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic media, superior to that of commercial Pt/graphene and IrO2catalysts. Our results offer valuable insights for the selection of elements as catalysts for various applications.

    DOI: 10.1039/d1sc01981c

    Web of Science

    Scopus

    PubMed

  43. Flash sintering for BaTiO<sub>3</sub> with square alternating current field including zero-field duration 招待有り 査読有り

    Umemura, R; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   128 巻 ( 12 ) 頁: 1018 - 1023   2020年12月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    The shrinkage behavior of barium titanate (BaTiO3) green compacts during flash sintering with a square alternating current (AC) field including a zero-field duration (AC-pulse wave) was investigated. It was found that an AC-pulse wave is effective for the densification of BaTiO3 green compacts without reduction and discharge, which is confirmed by transmission electron microscopy and electron energy loss spectroscopy. BaTiO3 sintered polycrystal was obtained at a furnace temperature of 1000 °C by the optimal AC-pulse conditions of 285 V/cm at 250 Hz and a duty ratio of 30 %. A waveform with alternating polarity and the inclusion of a zero-field duration is shown to be possibly useful for flash sintering of oxide materials including altervalent cations.

    DOI: 10.2109/jcersj2.20181

    Web of Science

    Scopus

  44. H<sub>2</sub> production from methane decomposition by fullerene at low temperature 査読有り

    Tokunaga, T; Kuno, K; Kawakami, T; Yamamoto, T; Yoshigoe, A

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   45 巻 ( 28 ) 頁: 14347 - 14353   2020年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:International Journal of Hydrogen Energy  

    Carbon materials have previously been reported to work as catalysts for hydrogen (H2) production from hydrocarbons. Mechanisms of the catalytic behavior of graphite and carbon black (CB) have often been discussed in literature. Graphite and CB is constructed from mainly 6-membered rings with sp2 bonds. To understand the catalytic behavior of carbon materials for H2 production by methane (CH4) decomposition, the catalytic behavior of fullerenes with 6-membered rings and also those comprising 5- and 7-membered rings with sp2 bonds and their associated mechanisms should be investigated. In this study, the fullerene catalyst activity has been investigated using gas chromatography and the electronic states and nanoscale structures have been analyzed. H2 production started at 400 °C and the H2 production rate gradually increased with time, and the activation energy of the fullerene for H2 production by CH4 decomposition was found to be 166 kJ/mol. Moreover, in situ heating X-ray photon spectroscopy (XPS) measurements showed that the π-π∗ transition signal becomes stronger with increasing temperature above the threshold of 300 °C. The transition of the π electrons to π∗ orbitals upon heating is expected to decompose CH4 absorbed on fullerene. Moreover, transmission electron microscopy (TEM) analysis revealed that the generated carbon atoms from the CH4 decomposition were deposited onto the surfaces of the fullerenes, forming amorphous and layered concentric sphere carbon. Amorphous carbon is reported to not work as a catalyst for CH4 decomposition at around 400 °C. From XPS analysis and TEM observations of these two structures, it is anticipated that the ring structures without 6-membered rings in carbon materials with sp2 bonding contribute to this catalytic behavior for CH4 decomposition at a low temperature of 400 °C.

    DOI: 10.1016/j.ijhydene.2020.03.178

    Web of Science

    Scopus

  45. Blue photo luminescence from 3 mol%Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> polycrystals sintered by flash sintering under an alternating current electric field 査読有り

    Yamashita, Y; Kurachi, T; Tokunaga, T; Yoshida, H; Yamamoto, T

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   40 巻 ( 5 ) 頁: 2072 - 2076   2020年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the European Ceramic Society  

    We investigated the photoluminescence (PL) properties of 3 mol%Y2O3-ZrO2 (3YSZ) polycrystals. The 3YSZ polycrystals were prepared by an isothermal flash sintering technique in which an alternating electric field was applied at a predetermined furnace temperature. After flash sintering, clear, visibly blue PL at 2.82 eV (440 nm) was confirmed under an ultraviolet light (3.4 eV (365 nm)); however, no visible PL was observed from 3YSZ polycrystals conventionally sintered using the same raw powders. Thus, the emission of blue PL was induced by the electric field applied during sintering. The obtained PL band was related to excitation at 3.87 eV (320 nm), which is possibly assigned to the singly ionized associated oxygen vacancy defects (AOD + centers). Furthermore, the blue emission was stable after high temperature annealing at 1400 °C for 1 h in air. We possibly attribute the emission of this PL to the stabilization of AOD + centers by the electric field loading during flash sintering.

    DOI: 10.1016/j.jeurceramsoc.2019.12.060

    Web of Science

    Scopus

  46. Suppression of nitridation of yttria-doped zirconia during flash sintering 査読有り 国際共著

    Kurachi, T; Yamashita, Y; Tokunaga, T; Yoshida, H; Yamamoto, T

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   103 巻 ( 5 ) 頁: 3002 - 3007   2020年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Ceramic Society  

    The effect of direct current (DC) and alternating current (AC) on nitridation of 3 mol% Y2O3-doped ZrO2 (3YSZ) after keeping in a flash state for 1 hour was investigated. The inside of the DC-flashed compact was confirmed to exhibit blacking. Scanning transmission electron microscopy, electron energy loss spectroscopy, and X-ray diffraction analysis revealed that zirconium nitrides formed in the blackened area. In contrast, a uniformly densified compact without blackening was obtained by AC fields. No zirconium nitrides formed in the compacts exposed to AC fields even when the flash state was maintained for 1 hour. Therefore, AC fields are effective to suppress nitridation of 3YSZ during flash sintering.

    DOI: 10.1111/jace.16990

    Web of Science

    Scopus

  47. <i>In situ</i> TEM observation of liquid-state Sn nanoparticles vanishing in a SiO<sub>2</sub> structure: a potential synthetic tool for controllable morphology evolution from core-shell to yolk-shell and hollow structures 査読有り 国際共著

    Zhu, S; Nguyen, MT; Tokunaga, T; Wen, CY; Yonezawa, T

    NANOSCALE ADVANCES   2 巻 ( 4 ) 頁: 1456 - 1464   2020年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Nanoscale Advances  

    Precise design of hollow nanostructures can be realized via various approaches developed in the last two decades, endowing nanomaterials with unique structures and outstanding performances, showing their usefulness in a broad range of fields. Herein, we demonstrate the formation of SnO2@SiO2 hollow nanostructures, for the first time, by interaction between liquid state Sn cores and SiO2 shell structures inside Sn@SiO2 core-shell nanoparticles with real-time observation via in situ transmission electron microscopy (TEM). Based on the in situ results, designed transformation of the nanoparticle structure from core-shell Sn@SiO2 to yolk-shell Sn@SiO2 and hollow SnO2@SiO2 is demonstrated, showing the controllable structure of core-shell Sn@SiO2 nanoparticles via fixing liquid-state Sn inside a SiO2 shell which has a certain Sn containing capacity. The present approach expands the toolbox for the design and preparation of yolk-shell and hollow nanostructures, thus providing us with a new strategy for fabrication of more complicated nanostructures.

    DOI: 10.1039/c9na00782b

    Web of Science

    Scopus

    PubMed

  48. Highly Correlated Size and Composition of Pt/Au Alloy Nanoparticles via Magnetron Sputtering onto Liquid 査読有り 国際誌

    Deng, LL; Nguyen, MT; Shi, JM; Chau, YTR; Tokunaga, T; Kudo, M; Matsumura, S; Hashimoto, N; Yonezawa, T

    LANGMUIR   36 巻 ( 12 ) 頁: 3004 - 3015   2020年3月

     詳細を見る

    記述言語:英語   出版者・発行元:Langmuir  

    Pt/Au alloy nanoparticles (NPs) in a wide composition range have been synthesized by room-temperature simultaneous sputter deposition from two independent magnetron sources onto liquid PEG (MW = 600). The prepared NPs were alloyed with the face-centered cubic (fcc) structure. In addition, the particle sizes, composition, and shape are strongly correlated but can be tailored by an appropriate variation of the sputtering parameters. No individual particle but large agglomerates with partial alloy structure formed at Pt content of less than 16 atom %. Highly dispersed NPs with no agglomeration were observed in PEG when the quantity of Pt is more than 26 atom %. On the other hand, a small amount of Pt could terminate the agglomeration of Au when sputtering on the grids for transmission electron microscope observation. Our experiment and computer simulation carried out by two different methods indicate that the composition-dependent particle size of Pt/Au can be explained by the atomic concentration, formation energy of the cluster, and interaction between different metal atoms and the PEG molecule.

    DOI: 10.1021/acs.langmuir.0c00152

    Web of Science

    Scopus

    PubMed

  49. Synthesis of composition-tunable Pd-Cu alloy nanoparticles by double target sputtering

    Chau, YTR; Nguyen, MT; Zhu, MB; Romier, A; Tokunaga, T; Yonezawa, T

    NEW JOURNAL OF CHEMISTRY   44 巻 ( 12 ) 頁: 4704 - 4712   2020年3月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:New Journal of Chemistry  

    In this work, we introduce a green synthesis technique, double-target sputtering into a liquid polymer-polyethylene glycol (PEG, M. W. = 600), to synthesize palladium-copper (Pd-Cu) alloy nanoparticles (NPs) dispersed in PEG. The composition of Pd and Cu in the alloy NPs can be controlled and varied by applying different sputtering currents for Pd and Cu targets. The particle sizes of the Pd-Cu NPs are maintained in the range of 2.4-2.5 nm for various Pd-Cu compositions. Oxidation issues and crystallinity enhancement are discussed.

    DOI: 10.1039/d0nj00288g

    Web of Science

    Scopus

  50. Blue photoluminescence at room temperature from Y<sub>2</sub>O<sub>3</sub>-doped ZrO<sub>2</sub> polycrystals sintered by flash sintering

    Yamashita, Y; Itoh, A; Tokunaga, T; Yoshida, H; Yamamoto, T

    APPLIED PHYSICS EXPRESS   13 巻 ( 3 )   2020年3月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Physics Express  

    Photoluminescence band variation of Y2O3-doped ZrO2 (YSZ) polycrystals was investigated for flash-sintered YSZ polycrystals. Nearly full density could be obtained by flash sintering under an alternating current field of 100 V cm-1, 100 Hz, limiting current of 1000 mA and at 1200 °C for 5 min. The flash-sintered YSZ polycrystals emitted blue photoluminescence even at room temperature under excitation of a handheld ultraviolet light, which could be observed with the naked eye. By contrast, conventionally sintered YSZ polycrystals emitted no photoluminescence despite using the same raw powders. In addition, the photoluminescence bands were tunable by varying the Y2O3 content.

    DOI: 10.35848/1882-0786/ab7710

    Web of Science

    Scopus

  51. Green Synthesis of Size-Tunable Iron Oxides and Iron Nanoparticles in a Salt Matrix 査読有り

    Nguyen, MT; Yu, K; Tokunaga, T; Boonyaperm, K; Kheawhom, S; Arita, M; Yonezawa, T

    ACS SUSTAINABLE CHEMISTRY & ENGINEERING   7 巻 ( 21 ) 頁: 17697 - 17705   2019年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Sustainable Chemistry and Engineering  

    This research is devoted for the synthesis of Fe oxide and Fe nanoparticles (NPs) via, respectively, thermal decomposition of iron(III) oleate and H2 reduction of either iron(III) oleate or iron oxide NPs in a NaCl matrix. Lowering the weight ratios of metal precursor to NaCl and synthesis temperature results in smaller particle sizes. A higher uniformity of Fe NPs can be achieved with a two-step synthesis, that is, thermal decomposition of iron oleate followed by H2 reduction of iron oxides, with the milling of iron oxides and NaCl prior to the reduction step. Fe NPs obtained in this study are stable in the air for long-time storage. It is found that thin oxide and C layers on the particle surface are responsible for their stability.

    DOI: 10.1021/acssuschemeng.9b03950

    Web of Science

    Scopus

  52. Technique to control specimen electric current during a flash state with alternating current electric fields 査読有り

    Yamashita, Y; Kurachi, T; Tokunaga, T; Yoshida, H; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   127 巻 ( 11 ) 頁: 849 - 851   2019年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    A simple technique to control the specimen electric current during flash sintering was developed using AC electric fields in 3 mol% Y2O3-doped ZrO2. Flash sintering is characterized by the occurrence of a flash event, i.e., a spike in the specimen electric current, which makes it difficult to control the specimen electric current at/ after the flash event for AC electric fields. However, AC electric fields are very attractive from the viewpoint of a suppression of the severe reduction arising from the unidirectional ionic flow during the flash event, which is a fatal phenomenon with DC electric fields. In this study, we develop a simple technique to control the AC electric fields at/after the flash event by limiting the AC electric fields under certain values. As a result, the flash state after the flash event is successfully maintained. Further, it is found that 3 mol% Y2O3-doped ZrO2 compacts prepared by DC- and AC-flash sintering emit blue fluorescence (FL) under 254 nm ultraviolet light. The blue FL is not obtained in the compacts prepared by conventionally-sintering. The application of electric fields is confirmed to result in the blue florescent properties of 3 mol% Y2O3-doped ZrO2 compacts.

    DOI: 10.2109/jcersj2.19144

    Web of Science

    Scopus

  53. One-Minute Joule Annealing Enhances the Thermoelectric Properties of Carbon Nanotube Yarns via the Formation of Graphene at the Interface 査読有り

    Hada, M; Hasegawa, T; Inoue, H; Takagi, M; Omoto, K; Chujo, D; Iemoto, S; Kuroda, T; Morimoto, T; Hayashi, T; Iijima, T; Tokunaga, T; Ikeda, N; Fujimori, K; Itoh, C; Nishikawa, T; Yamashita, Y; Kiwa, T; Koshihara, S; Maeda, S; Hayashi, Y

    ACS APPLIED ENERGY MATERIALS   2 巻 ( 10 ) 頁: 7700 - 7708   2019年10月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Applied Energy Materials  

    Interfaces in nanocarbon materials are highly important, as they determine the properties of carbon-based devices. In terms of carrier and thermal transport properties, the interfacial features are often more important than the intrinsic characteristics. Herein, we describe how 1 min Joule annealing of carbon nanotube (CNT) yarns can convert the interfacial amorphous carbon into graphene fragments. After 1 min Joule annealing, we have obtained multiwalled CNT yarns with extremely high Seebeck coefficients (±100 μV/K) and high thermoelectric power factor (400 and 1000 μW/mK2) at room temperature, both with or without polyethylenimine doping. Theoretical simulations and experimental measurements helped to determine the optimal annealing conditions in terms of a rapid transformation of the interfacial amorphous carbon between the bundled CNTs in the yarn into graphene fragments at â¼2000 K. The present approach represents significant progress in energy materials science, as it provides a guiding principle for the design of interfaces in nanocarbon materials with potential applications in energy-harvesting systems.

    DOI: 10.1021/acsaem.9b01736

    Web of Science

    Scopus

  54. Selective Reduction Mechanism of Graphene Oxide Driven by the Photon Mode <i>versus</i> the Thermal Mode 査読有り 国際誌

    Hada, M; Miyata, K; Ohmura, S; Arashida, Y; Ichiyanagi, K; Katayama, I; Suzuki, T; Chen, W; Mizote, S; Sawa, T; Yokoya, T; Seki, T; Matsuo, J; Tokunaga, T; Itoh, C; Tsuruta, K; Fukaya, R; Nozawa, S; Adachi, S; Takeda, J; Onda, K; Koshihara, S; Hayashi, Y; Nishina, Y

    ACS NANO   13 巻 ( 9 ) 頁: 10103 - 10112   2019年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Nano  

    A two-dimensional nanocarbon, graphene, has attracted substantial interest due to its excellent properties. The reduction of graphene oxide (GO) has been investigated for the mass production of graphene used in practical applications. Different reduction processes produce different properties in graphene, affecting the performance of the final materials or devices. Therefore, an understanding of the mechanisms of GO reduction is important for controlling the properties of functional two-dimensional systems. Here, we determined the average structure of reduced GO prepared via heating and photoexcitation and clearly distinguished their reduction mechanisms using ultrafast time-resolved electron diffraction, time-resolved infrared vibrational spectroscopy, and time-dependent density functional theory calculations. The oxygen atoms of epoxy groups are selectively removed from the basal plane of GO by photoexcitation (photon mode), in stark contrast to the behavior observed for the thermal reduction of hydroxyl and epoxy groups (thermal mode). The difference originates from the selective excitation of epoxy bonds via an electronic transition due to their antibonding character. This work will enable the preparation of the optimum GO for the intended applications and expands the application scope of two-dimensional systems.

    DOI: 10.1021/acsnano.9b03060

    Web of Science

    Scopus

    PubMed

  55. Porous ZnV<sub>2</sub>O<sub>4</sub> Nanowire for Stable and High-Rate Lithium-Ion Battery Anodes 査読有り

    De Juan-Corpuz, LMZ; Nguyen, MT; Corpuz, RD; Yonezawa, T; Rosero-Navarro, NC; Tadanaga, K; Tokunaga, T; Kheawhom, S

    ACS APPLIED NANO MATERIALS   2 巻 ( 7 ) 頁: 4247 - 4256   2019年7月

     詳細を見る

    記述言語:日本語   出版者・発行元:American Chemical Society ({ACS})  

    Porous ZnV2O4 nanowires (NWs) were successfully prepared by hydrothermal reaction followed by calcination. Despite the porous structure, these porous ZnV2O4 NWs are single crystal with {220} facets and a wire direction along the c-axis. On the basis of an electrochemical test, these porous ZnV2O4 NWs have better cycling stability and higher specific capacity (i.e., 460 mA h g-1 after 100 cycles and 149 mA h g-1 after 1000 cycles using 1 and 5 A g-1 current densities, respectively) compared to other morphologies (i.e., spherical and coral-like morphologies). As a ternary transition metal oxide, the produced porous ZnV2O4 NWs undergo phase transformation without compromising the resulting capacity. On the other hand, the CV curves at different scan rates indicate a pseudocapacitive electrochemical behavior of the porous ZnV2O4.

    DOI: 10.1021/acsanm.9b00703

    Web of Science

    Scopus

  56. Preparation and Growth Mechanism of Pt/Cu Alloy Nanoparticles by Sputter Deposition onto a Liquid Polymer 査読有り 国際誌

    Deng, LL; Nguyen, MT; Mei, S; Tokunaga, T; Kudo, M; Matsumura, S; Yonezawa, T

    LANGMUIR   35 巻 ( 25 ) 頁: 8418 - 8427   2019年6月

     詳細を見る

    記述言語:英語   出版者・発行元:Langmuir  

    We use a green sputtering technique to deposit a Pt/Cu alloy target on liquid polyethylene glycol (PEG) to obtain well-dispersed and stable Pt29Cu71 alloy nanoparticles (NPs). The effects of sputtering current, rotation speed of the stirrer, sputtering time, sputtering period, and temperature of PEG on the particle size are studied systematically. Our key results demonstrate that the aggregation and growth of Pt/Cu alloy NPs occurred at the surface as well as inside the liquid polymer after the particles landed on the liquid surface. According to particle size analysis, a low sputtering current, high rotation speed for the stirrer, short sputtering period, and short sputtering time are found to be favorable for producing small-sized single crystalline alloy NPs. On the other hand, varying the temperature of the liquid PEG does not have any significant impact on the particle size. Thus, our findings shed light on controlling NP growth using the newly developed green sputtering deposition technique.

    DOI: 10.1021/acs.langmuir.9b01112

    Web of Science

    Scopus

    PubMed

  57. Size-Tunable Alumina-Encapsulated Sn-Based Phase Change Materials for Thermal Energy Storage 査読有り

    Zhu, SL; Nguyen, MT; Tokunaga, T; Yonezawa, T

    ACS APPLIED NANO MATERIALS   2 巻 ( 6 ) 頁: 3752 - 3760   2019年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Applied Nano Materials  

    The most commonly used phase change materials (PCMs), like organic compounds and inorganic salts, were limited in application by their low thermal conductivity. Herein, for the first time, alumina-encapsulated metallic Sn-based PCMs, named Sn@Al2O3, were successfully fabricated with tunable size (60-2000 nm) by a facile process from low-cost chemicals. The robust fabrication process consists of a surfactant-free solvothermal synthesis of SnO2 spheres, boehmite treatment on SnO2 spheres, calcination in the air, and the final hydrogen reduction to transform SnO2 to metallic Sn, endowing the PCMs with high potential for mass production. The as-obtained Sn@Al2O3 showed a core-shell structure, in which a main metallic Sn core located in the center covered with an Al2O3 shell with small Sn nanoparticles distributed inside. The boehmite treatment, in which the penetration of aluminum species into SnO2 spheres played an important role, was found to be responsible for the unique structure formation of final Sn@Al2O3. The understanding of structure formation mechanism gives the possibilities of a new facile way for the synthesis of metal nanoparticles and particle-distributed nanostructures. The obtained Sn@Al2O3 particles not only have high PCM content (92.37 wt %) but also show a stable thermal behavior and morphology during 100 melt-freeze cycles in the air atmosphere. Furthermore, the low melting temperature of the PCM core, combined with high thermal conductivity of both core material (Sn, 66.8 W m-1 K-1) and shell material (Al2O3, 35 W m-1 K-1), makes Sn@Al2O3 potentially suitable for rapid thermal energy storage in the range 100-300 °C.

    DOI: 10.1021/acsanm.9b00649

    Web of Science

    Scopus

  58. Topologically immobilized catalysis centre for long-term stable carbon dioxide reforming of methane 査読有り 国際誌

    Shoji, S; Peng, XB; Imai, T; Kumar, PSM; Higuchi, K; Yamamoto, Y; Tokunaga, T; Arai, S; Ueda, S; Hashimoto, A; Tsubaki, N; Miyauchi, M; Fujita, T; Abe, H

    CHEMICAL SCIENCE   10 巻 ( 13 ) 頁: 3701 - 3705   2019年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Science  

    Methane reforming at low temperatures is of growing importance to mitigate the environmental impact of the production of synthesis gas, but it suffers from short catalyst lifetimes due to the severe deposition of carbon byproducts. Herein, we introduce a new class of topology-tailored catalyst in which tens-of-nanometer-thick fibrous networks of Ni metal and oxygen-deficient Y2O3 are entangled with each other to form a rooted structure, i.e., Ni#Y2O3. We demonstrate that the rooted Ni#Y2O3 catalyst stably promotes the carbon-dioxide reforming of methane at 723 K for over 1000 h, where the performance of traditional supported catalysts such as Ni/Y2O3 diminishes within 100 h due to the precluded mass transport by accumulated carbon byproducts. In situ TEM demonstrates that the supported Ni nanoparticles are readily detached from the support surface in the reaction atmosphere, and migrate around to result in widespread accumulation of the carbon byproducts. The long-term stable methane reforming over the rooted catalyst is ultimately attributed to the topologically immobilized Ni catalysis centre and the synergistic function of the oxygen-deficient Y2O3 matrix, which successfully inhibits the accumulation of byproducts.

    DOI: 10.1039/c8sc04965c

    Web of Science

    Scopus

    PubMed

  59. Nanoporous Nickel Composite Catalyst for the Dry Reforming of Methane 査読有り 国際誌

    Fujita, T; Peng, XB; Yamaguchi, A; Cho, Y; Zhang, YZ; Higuchi, K; Yamamoto, Y; Tokunaga, T; Arai, S; Miyauchi, M; Abe, H

    ACS OMEGA   3 巻 ( 12 ) 頁: 16651 - 16657   2018年12月

     詳細を見る

    記述言語:英語   出版者・発行元:ACS Omega  

    The development of efficient catalysts with high activities and durabilities for use in the dry reforming of methane (DRM) is desirable but challenging. We report the development of a nanoporous nickel composite (nanoporous Ni/Y2O3) via a facile one-step dealloying technique, for use in the DRM. Focusing on the low-temperature DRM, our composite possessed remarkable activity and durability against coking compared with conventional particle-based Ni catalysts. This was attributed to the aluminum oxides present on the Ni surface, which suppress pore coarsening. In addition, the inert bundled Y2O3 nanowires are suitable for use as substrates for nanoporous Ni.

    DOI: 10.1021/acsomega.8b02023

    Web of Science

    Scopus

    PubMed

  60. Intergranular amorphous films formed by DC electric field in pure zirconia 査読有り

    Morisaki, N; Yoshida, H; Kobayashi, T; Tokunaga, T; Yamamoto, T

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   101 巻 ( 8 ) 頁: 3282 - 3287   2018年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Ceramic Society  

    It is difficult to obtain pure ZrO2 sintered compacts with a bulk style at room temperature because a large volumetric expansion from tetragonal to monoclinic phase (t/m) transformation occurs at around 1000°C, which is lower than the sintering temperature. In contrast, pure monoclinic ZrO2 can be consolidated without shattering using flash-sintering at 1350°C for 5 minutes under an applied DC electric field of 175 V/cm. High-resolution transmission electron microscopy and electron energy loss spectroscopy have revealed that amorphous films are formed along grain boundaries after flash-sintering at 1350°C for 5 minutes. Monoclinic ZrO2 flash-sintered compact including the amorphous films are able to survive without shattering through the t/m transformation, as the amorphous films partially absorb the large volumetric expansion arising from the t/m transformation. The formation of the amorphous films results from the severe reducing condition due to the applied DC electric fields during flash-sintering.

    DOI: 10.1111/jace.15485

    Web of Science

    Scopus

  61. Ligand free green plasma-in-liquid synthesis of Au/Ag alloy nanoparticles 査読有り

    Cempel, D; Nguyen, MT; Ishida, Y; Tokunaga, T; Yonezawa, T

    NEW JOURNAL OF CHEMISTRY   42 巻 ( 8 ) 頁: 5681 - U9   2018年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:New Journal of Chemistry  

    Au/Ag alloy nanoparticles (NPs) were successfully prepared by a one step synthesis using HAuCl4 and [Ag(NH3)2]+ as the corresponding precursors in a microwave-induced plasma in liquid process (MWPLP) without the addition of any organic protecting or reducing agents. The time dependent reduction and particle formation during the 140 min plasma discharge were studied with TEM, UV-vis extinction spectra, and ICP-OES. After 140 min, the HAADF-STEM and EDX results indicated that the obtained Au/Ag NPs were alloy NPs. Varying the input molar ratios of the metal precursors allowed for control of the composition of the Au/Ag alloy NPs.

    DOI: 10.1039/c7nj05154a

    Web of Science

    Scopus

  62. Sputter Deposition toward Short Cationic Thiolated Fluorescent Gold Nanoclusters: Investigation of Their Unique Structural and Photophysical Characteristics Using High-Performance Liquid Chromatography 査読有り 国際誌

    Ishida, Y; Morita, A; Tokunaga, T; Yonezawa, T

    LANGMUIR   34 巻 ( 13 ) 頁: 4024 - 4030   2018年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Langmuir  

    We herein present the preparation of short, bulky cationic thiolate (thiocholine)-protected fluorescent Au nanoclusters via sputter deposition over a liquid polymer matrix. The obtained Au nanoclusters showed near-infrared fluorescence and had an average core diameter of 1.7 ± 0.6 nm, which is too large compared to that of the reported fluorescent Au nanoclusters prepared via chemical means. We revealed the mechanism of formation of this unique material using single-particle electron microscopy, optical measurements, X-ray photoelectron spectroscopy (XPS), and high-performance liquid chromatography fractionations. The noncrystallized image was observed via single-particle high-angle annular dark-field scanning transmission electron microscopy observations and compared with chemically synthesized crystalline Au nanoparticle with the same diameter, which demonstrated the unique structural characteristic speculated via XPS. The size fractionation and size-dependent fluorescence measurement, together with other observations, indicated that the nanoclusters most probably contained a mixture of very small fluorescent species in their aggregated form and were derived from the sputtering process itself and not from the interaction between thiol ligands.

    DOI: 10.1021/acs.langmuir.8b00067

    Web of Science

    Scopus

    PubMed

  63. Au/Cu Bimetallic Nanoparticles via Double-Target Sputtering onto a Liquid Polymer 査読有り 国際誌

    Nguyen, MT; Zhang, H; Deng, LL; Tokunaga, T; Yonezawa, T

    LANGMUIR   33 巻 ( 43 ) 頁: 12389 - 12397   2017年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Langmuir  

    Alloy nanoparticles (NPs) of a bimetal system, Au/Cu, that form intermetallic compounds in a bulk state have been successfully produced using a double-target sputtering technique onto a low-cost and biocompatible liquid polymer (polyethylene glycol, PEG). The formation of an Au/Cu solid solution alloy in individual NPs was revealed by scanning transmission electron microscopy-energy-dispersive X-ray elemental mapping analysis. Altering the sputter currents for Au and Cu targets resulted in a tailored NP composition, but the particle sizes did not significantly vary. We found similar structures, sizes, and optical properties of Au/Cu NPs obtained by double-head sputtering on carbon-coated transmission electron microscopy grids or PEG and by Au/Cu alloy target sputtering. Random alloy formation occurred in matrix sputtering using double-target heads. This method is advantageous for manipulating the alloy composition through highly independent control of sputter parameters for each metal target.

    DOI: 10.1021/acs.langmuir.7b03194

    Web of Science

    Scopus

    PubMed

  64. In-Situ TEM Study of a Nanoporous Ni-Co Catalyst Used for the Dry Reforming of Methane 査読有り

    Fujita, T; Higuchi, K; Yamamoto, Y; Tokunaga, T; Arai, S; Abe, H

    METALS   7 巻 ( 10 ) 頁: 406   2017年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Metals  

    We performed in-situ transmission electron microscopy (TEM) on a dealloyed nanoporous NiCo catalyst used for the dry reforming of methane (DRM) to investigate the origin of the catalytic activity and structural durability. The in-situ observations and local chemical analysis indicated that the DRM induced chemical demixing of Ni and Co accompanied by grain refinement, implying possible “synergic effects” in a general bimetallic NiCo catalyst when used for the DRM.

    DOI: 10.3390/met7100406

    Web of Science

    Scopus

  65. Consolidation of undoped, monoclinic zirconia polycrystals by flash sintering 査読有り

    Morisaki, N; Yoshida, H; Tokunaga, T; Sasaki, K; Yamamoto, T

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   100 巻 ( 9 ) 頁: 3851 - 3857   2017年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Ceramic Society  

    Consolidated, monoclinic ZrO2 polycrystal was produced from undoped ZrO2 powders in air by flash sintering at the sintering temperature of 1350°C for 5 minutes or 3 hours under an applied DC electric field of 175 V/cm. When the ZrO2 was heated under the applied DC field, the electric current of the specimen steeply increased at the furnace temperature of 1335°C below the sintering temperature of 1350°C. When the furnace temperature was decreased from the sintering temperature of 1350°C to room temperature, volumetric expansion associated with tetragonal-to-monoclinic phase transformation gradually took place at the furnace temperature from 1000°C to 750°C, and monoclinic ZrO2 body was remained consolidated even at room temperature in both specimens. In contrast, conventionally sintered ZrO2 without applying DC field exhibited the abrupt volumetric expansion at about 1000°C, and shattered. SEM observation revealed the presence of grain-boundary second phase in the flash-sintered specimen for 3 hours, which is a possible origin of keeping a bulk body at room temperature. The thinner second phase is considered to be formed also in the flash-sintered specimen for 5 minutes, although the formation of the phase could not be observed clearly by SEM observation. On the other hand, XRD measurements showed that <001> directions of the monoclinic ZrO2 grains were oriented along the applied DC field after the isothermal flash sintering for 3 hours while the grain alignment could not be observed in flash-sintered specimen for 5 minutes. The alignment of ZrO2 grains observed in the isothermal flash sintering is considered to be closely related to the preferential direction of oxygen ionic conduction and the second phase formed along grain boundaries.

    DOI: 10.1111/jace.14954

    Web of Science

    Scopus

  66. Electric current-controlled synthesis of BaTiO<sub>3</sub> 査読有り

    Nakagawa, Y; Yoshida, H; Uehashi, A; Tokunaga, T; Sasaki, K; Yamamoto, T

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   100 巻 ( 9 ) 頁: 3843 - 3850   2017年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Ceramic Society  

    In BaTiO3, flash-sintering associated with a surge of the specimen electric current sometimes results in an inhomogeneous microstructure including Ti-excess secondary phases because of discharging. We applied field-assisted sintering technique (FAST) under precisely controlled specimen current that was set just below the threshold value for the occurrence of flash event for BaTiO3, to avoid the occurrence of the discharging. As a result, uniform and fine-grained compacts were obtained without any secondary phases. A relative density of approximately 92% was achieved under FAST condition of 100 V/cm with a limiting current of 72 mA and soaking time of 3 hours at 1070°C. The voltages during sintering under a constant current of 72 mA were found to decrease during the soaking process. Electron energy loss spectroscopy revealed the generation of excess oxygen vacancies at/near grain boundaries. The excess oxygen vacancies induced by application of DC electric fields were confirmed to reduce the voltages and to retard the shrinkage rate in a final sintering stage.

    DOI: 10.1111/jace.14938

    Web of Science

    Scopus

  67. Structural Control Parameters for Formation of Single-Crystalline ss-Sn Nanorods in Organic Phase 査読有り

    Lyn Marie Z. De Juan, Mai Thanh Nguyen, Tetsu Yonezawa, Tomoharu Tokunaga, Hiroki Tsukamoto, Yohei Ishida

    CRYSTAL GROWTH & DESIGN   17 巻 ( 9 ) 頁: 4554 - 4562   2017年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    For the first time, investigation on the effect of lowering the synthesis temperature below room temperature (10 to -10 degrees C) and increasing the viscosity of the reaction solution at certain temperatures has been used to trigger the formation of single-crystalline ss-Sn nanorods (NRs) in a chemical synthesis using an organic solvent. These two parameters govern the energy of the particles in the solution, thereby mediating the selective attachment to the nuclei and the preferential growth of Sn along the c-axis. The length and aspect ratio of the NRs were inversely proportional to the synthesis temperature and directly proportional to the viscosity of the reaction solution. In addition, we found that poly(vinylpyrrolidone) with a high molecular weight aided the formation of longer and higher aspect ratio NRs via the bridge flocculation effect.

    DOI: 10.1021/acs.cgd.7b00227

    Web of Science

  68. Small Nanosized Oxygen-Deficient Tungsten Oxide Particles: Mechanistic Investigation with Controlled Plasma Generation in Water for Their Preparation 査読有り 国際誌

    Ishida, Y; Motono, S; Doshin, W; Tokunaga, T; Tsukamoto, H; Yonezawa, T

    ACS OMEGA   2 巻 ( 8 ) 頁: 5104 - 5110   2017年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    Production of oxygen-deficient tungsten oxide nanoparticles with a diameter of around 10 nm have been successfully developed using a microwave-induced plasma in liquid technique. The prepared blue-green nanoparticles exhibit strong absorption in the visible region; thus, these could be efficient visible-light photocatalysts. The high-angle annular dark-field images revealed the dislocation of tungsten, which causes oxygen deficiencies.

    DOI: 10.1021/acsomega.7b00986

    Web of Science

    Scopus

    PubMed

  69. Water transport phenomena through membranes consisting of vertically-aligned double-walled carbon nanotube array

    Matsumoto, H; Tsuruoka, S; Hayashi, Y; Abe, K; Hata, K; Zhang, SL; Saito, Y; Aiba, M; Tokunaga, T; Iijima, T; Hayashi, T; Inoue, H; Amaratunga, GAJ

    CARBON   120 巻   頁: 358 - 365   2017年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Carbon  

    Nanofluidics in CNTs is argumentative though it is theoretically calculated by various reports. It is because only a few of experimental reports are available, and the measured permeability is not so large as that suggested from the theoretical calculations. Also, water motion suppression in the confined space has not been exhibited by flux measurement. The present work explores these yet-unsolved discrepancies using the measurable size membrane of vertically aligned double-walled carbon nanotube array, which is borne with durability and flexibility, and a conventional measurement method is applied to the membranes. Water motion suppression occurs in the CNT confined space significantly, depending on temperature. Additionally, it is confirmed that the obtained permeability correlates to the reported experimental results with regard to the relationship between CNT length and permeability, and the correlation does not agree with permeability calculated from the Hagen-Poiseuille law. These results pose an insight into the inherent water transport characteristics in the CNT confined space.

    DOI: 10.1016/j.carbon.2017.05.034

    Web of Science

    Scopus

  70. Nanophase-separated Ni<sub>3</sub>Nb as an automobile exhaust catalyst 国際誌

    Tanabe, T; Imai, T; Tokunaga, T; Arai, S; Yamamoto, Y; Ueda, S; Ramesh, GV; Nagao, S; Hirata, H; Matsumoto, S; Fujita, T; Abe, H

    CHEMICAL SCIENCE   8 巻 ( 5 ) 頁: 3374 - 3378   2017年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Science  

    Catalytic remediation of automobile exhaust has relied on precious metals (PMs) including platinum (Pt). Herein, we report that an intermetallic phase of Ni and niobium (Nb) (i.e., Ni3Nb) exhibits a significantly higher activity than that of Pt for the remediation of the most toxic gas in exhaust (i.e., nitrogen monoxide (NO)) in the presence of carbon monoxide (CO). When subjected to the exhaust-remediation atmosphere, Ni3Nb spontaneously evolves into a catalytically active nanophase-separated structure consisting of filamentous Ni networks (thickness < 10 nm) that are incorporated in a niobium oxide matrix (i.e., NbOx (x < 5/2)). The exposure of the filamentous Ni promotes NO dissociation, CO oxidation and N2 generation, and the NbOx matrix absorbs excessive nitrogen adatoms to retain the active Ni sites at the metal/oxide interface. Furthermore, the NbOx matrix immobilizes the filamentous Ni at elevated temperatures to produce long-term and stable catalytic performance over hundreds of hours.

    DOI: 10.1039/c6sc05473k

    Web of Science

    Scopus

    PubMed

  71. Methane decomposition for hydrogen production by catalytic activity of carbon black under low flow rate conditions

    Tokunaga, T; Kishi, N; Yamakawa, K; Sasaki, K; Yamamoto, T

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   125 巻 ( 4 ) 頁: 185 - 189   2017年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the Ceramic Society of Japan  

    Recently, carbon materials were reported to work as catalysts for the production of H3 from hydrocarbons. However, the hydrogen production rate is extremely low. To broaden the scope of carbon materials as catalysts for the decomposition of hydrocarbons, a higher H3 production rate is required. Thus, the hydrogen production rate under conditions employing a low flow rate of hydrocarbon per unit area and a large quantity of carbon materials as the catalyst should be evaluated, and the influence of these conditions on the rate of H3 production by carbon materials should be discussed. Herein, the H3 production rate was measured under conditions employing a low flow rate of CH4 and a large quantity of carbon black (CB) as a catalyst. H3 production started at 600°C and the production rate was less than 0.1%. The transmission electron microscope image of CB heated in CH4 atmosphere demonstrated that a low flow rate of CH4 does not affect the reaction site (i.e., graphite edges) of CB. However, the H3 production rate was extremely low compared to that achieved with a high flow rate. It is proposed that there is an optimal flow rate for maintaining the catalytic activity at the graphite edge of CB for decomposition of CH4.

    DOI: 10.2109/jcersj2.16246

    Web of Science

    Scopus

  72. Preparation of Au/Pd Bimetallic Nanoparticles by a Microwave-Induced Plasma in Liquid Process

    Shirai, H; Nguyen, MT; Cempel, D; Tsukamoto, H; Tokunaga, T; Liao, YC; Yonezawa, T

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   90 巻 ( 3 ) 頁: 279 - 285   2017年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Bulletin of the Chemical Society of Japan  

    Au/Pd alloy nanoparticles (NPs) were successfully synthesized using HAuCl4, H2PdCl4, and α-thioglycerol as precursors and a stabilizer, respectively, by microwave-induced plasma in liquid process (MWPLP). After only several minutes of microwave irradiation, metallic NPs were obtained in aqueous environment without any reducing agent. The reduction mechanism of metal ions was confirmed by UV-vis spectral changes. The results from HAADF-STEM and EDS indicated that synthesized NPs were bimetallic Au/Pd. Moreover, XRD patterns of synthesized NPs implied that the composition of bimetallic NPs could be controlled by changing the initial ratio of metal precursors.

    DOI: 10.1246/bcsj.20160333

    Web of Science

    Scopus

  73. Directly determining the polarity of WC grains in WC-12 wt%Co alloy by ABF-STEM 査読有り

    Hayashi, Y; Tokunaga, T; Sasaki, K; Yamamoto, T

    INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS   62 巻   頁: 9 - 13   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:International Journal of Refractory Metals and Hard Materials  

    WC grains in WC–Co alloys are shaped as truncated triangular prisms, each with a basal plane of a (0001) truncated triangle and two {11̅00} prismatic planes, one narrower and one wider. This anisotropic shape is related to the polarity of the WC lattice, which comes from the difference in the spacing of the W and C layers in the (0001) projection. We directly determined the relationship between the two {11̅00} prismatic planes and the polarity of the WC lattice by using high-resolution scanning transmission electron microscopy (STEM). High-angle annular dark-field STEM and annular bright-field STEM revealed that the wider prismatic plane had W and C atomic layers with a shorter spacing, while the narrower plane had a longer spacing. The WC/Co interface on the wider prismatic side was atomically flat, while many steps formed on the surface of the narrower prismatic side. This difference in step formation at these interfaces could have come from the difference in how their W[sbnd]C bonds formed.

    DOI: 10.1016/j.ijrmhm.2016.10.013

    Web of Science

    Scopus

  74. Water transport phenomena through membranes consisting of vertically-aligned double-walled carbon nanotube array

    Hidetoshi Matsumoto, Shuji Tsuruoka, Yasuhiko Hayashi, Koji Abe, Kenjiro Hata, Shaoling Zhang, Yoshitaka Saito, Motohiro Aiba, Tomoharu Tokunaga, Toru Iijima, Takuma Hayashi

    Carbon   120 巻   頁: 358–365   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  75. Nanophase-separated Ni3Nb as Automobile Exhaust Catalysts 査読有り

    Toyokazu Tanabe, Tsubasa Imai, Tomoharu Tokunaga, Shigeo Arai, Yuta Yamamoto, Shigenori Ueda, Gubbala V. Ramesh, Satoshi Nagao, Hirohito Hirata, Shin-ichi, Matsumoto, Takeshi Fujita, Hideki Abe

    Chemical Science   8 巻   頁: 3374-3378   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  76. Preparation of Au/Pd bimetallic nanoparticles by a microwave-induced plasma in liquid process 査読有り

    Hiroaki Shirai, Mai Thanh Nguyen, David Čempel, Hiroki Tsukamoto, Tomoharu Tokunaga, Ying-Chih Liao, and Tetsu Yonezawa

    Bulletin of the Chemical Society of Japan   90 巻 ( 3 ) 頁: 279-285   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  77. Methane Decomposition for Hydrogen Production by Catalytic Activity of Carbon Black under Low Flow Rate Conditions

    Tomoharu Tokunaga, Naoyuki Kishi, Kenya Yamakawa, Katsuhiro Sasaki, Takahisa Yamamoto

    ACS-Japan   125 巻 ( 4 ) 頁: 185-189   2017年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  78. Intentionally Encapsulated Metal Alloys within Vertically Aligned Multi-Walled Carbon Nanotube Array via Chemical Vapor Deposition Technique

    Hayashi Yasuhiko, Inoue Hirotaka, Hayashi Takuma, Hada Masaki, Nishikawa Takeshi, Tokunaga Tomoharu, Amaratunga G. A. J.

    2017 IEEE INTERNATIONAL CONFERENCE ON MANIPULATION, MANUFACTURING AND MEASUREMENT ON THE NANOSCALE (3M-NANO)     頁: 357-361   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Web of Science

  79. Intentionally Encapsulated Metal Alloys within Vertically Aligned Multi-Walled Carbon Nanotube Array via Chemical Vapor Deposition Technique 査読有り

    Yasuhiko Hayashi, Hirotaka Inoue, Takuma Hayashi, Masaki Hada, Takeshi Nishikawa, Tomoharu Tokunaga, G. A. J. Amaratunga

    2017 IEEE INTERNATIONAL CONFERENCE ON MANIPULATION, MANUFACTURING AND MEASUREMENT ON THE NANOSCALE (3M-NANO)     頁: 357 - 361   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    This paper presents a growth and characterization of vertically aligned PdxCo1-x alloy encapsulated inside Multi-Walled Carbon Nanotube (MWCNT) arrays on Pd/Co thin layers coated on Si substrate by a dc bias-enhanced plasma chemical vapor deposition (CVD) method. The Metal Alloy Encapsulated within MWCNTs (MAE-MWCNTs) were characterized by a scanning electron microscope (SEM) and a transmission electron microscopy (TEM). The SEM images show the teardrop-shape particles encapsulated within the tube top of MWCNTs. A vibrating sample magnetometer was used to study the magnetism of a large number of MAE-MWCNTs on Si substrate at room temperature. The hysteresis loop of the ME-MWCNTs shows clear ferromagnetic behavior and the easy axis of magnetization is parallel to the MEA-MWCNT tube axis, as can be elucidated from the large coercive fields and remanence values. Moreover, TEM off-axis electron holograms were used to study the magnetism of the individual MAE-MWCNT or the two pair of MAE-MWCNTs. Based on electron holography, we have successfully obtained the saturation magnetization of 0.7 T and 1.12 T for the individual MAE-MWCNT with diameters of 41 nm and 83 nm, respectively.

    Web of Science

  80. Double target sputtering into liquid 査読有り

    Mai Thanh Nguyen, Tetsu Yonezawa, Yuan Wang, Tomoharu Tokunaga

    Materials Letters   171 巻 ( 15 ) 頁: 75-78   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  81. Earth-Abundant and Durable Nanoporous Catalyst for Exhaust-Gas Conversion 査読有り

    Takeshi Fujita,Hideki Abe,Toyokazu Tanabe,Yoshikazu Ito,Tomoharu Tokunaga,Shigeo Arai,Yuta Yamamoto,Akihiko Hirata,Mingwei Chen

    Advanced Functional Materials     頁: 1-8   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  82. Hard-Templating Synthesis of Macroporous Platinum Microballs 査読有り

    Hiroaki Shirai, Yu-Yuan Huang, Tetsu Yonezawa,* Wei-Chen Chang, Tomoharu Tokunaga, Saad Alshehri, Bo Jiang, Yusuke Yamauchi, and Kevin C.-W. Wu

    Materials Letters   164 巻 ( 1 ) 頁: 488-492   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  83. Synthesis of zirconium oxynitride in air under DC electric fields 査読有り

    Nobuhiro Morisaki, Hidehiro Yoshida, Koji Matsui, Tomoharu Tokunaga, Katsuhiro Sasaki, Takahisa Yamamoto

    Applied Physics Letter   109 巻   頁: 083104(1)- 083104(4)   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  84. Formation of grain boundary second phase in BaTiO3 polycrystal under a high DC electric field at elevated temperatures 査読有り

    Hidehiro YOSHIDA, Akinori UEHASHI, Tomoharu TOKUNAGA, Katsuhiro SASAKI, Takahisa YAMAMOTO

    Journal of the Ceramic Society of Japan   124 巻 ( 4 ) 頁: 388-392   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  85. Matrix Sputtering into Liquid Mercaptan: From Blue-Emitting Copper Nanoclusters to Red-Emitting Copper Sulfide Nanoclusters 査読有り

    Matteo Porta, Mai Thanh Nguyen, Tomoharu Tokunaga, Yohei Ishida, Wei-Ren Liu, Tetsu Yonezawa

    Langmuir   32 巻   頁: 12159-12165   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  86. Matrix Sputtering into Liquid Mercaptan: From Blue-Emitting Copper Nanoclusters to Red-Emitting Copper Sulfide Nanoclusters 査読有り

    Matteo Porta, Mai Thanh Nguyen, Tomoharu Tokunaga, Yohei Ishida, Wei-Ren Liu, Tetsu Yonezawa

    Langmuir   32 巻   頁: 12159-12165   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  87. Hard-Templating Synthesis of Macroporous Platinum Microballs (MPtM) 査読有り

    Hiroaki Shirai, Yu-Yuan Huang, Tetsu Yonezawa,* Wei-Chen Chang, Tomoharu Tokunaga, Saad Alshehri, Bo Jiang, Yusuke Yamauchi, and Kevin C.-W. Wu

    Materials Letters   164 巻 ( 1 ) 頁: 488-492   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  88. Enhancement of sintering rates in BaTiO3 by controlling of DC electric current 査読有り

    Akinori Uehashi, Hdehiro Yoshida, Tomoharu Tokunaga, Katsuhiro Sasaki, Takahisa Yamamoto

      123 巻 ( 6 ) 頁: 465-468   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  89. In-situ observation of carbon nanotube yarn during voltage application 査読有り

    Tomoharu Tokunaga, Yasuhiko Hayashi, Toru Iijima, Yuki Uesugi, Masaki Unten, Katsuhiro Sasaki, Takahisa Yamamoto

    Micron   74 巻   頁: 30-34   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  90. Environment-Sensitive Thermal Coarsening of Nanoporous Gold 査読有り

    Satoko Kuwano-Nakatani, Takeshi Fujita, Kazuki Uchisawa, Daichi Umetsu, Yu Kase, Yusuke Kowata, Katsuhiko Chiba, Tomoharu Tokunaga, Shigeo Arai, Yuta Yamamoto, Nobuo Tanaka, Mingwei Chen

    MATERIALS TRANSACTIONS   56 巻 ( 4 ) 頁: 468-472   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  91. Plasma-Induced Tungsten Doping of TiO2 Nanoparticles for Enhanced Photocatalysis using Visible Light 査読有り

      17 巻 ( 38 ) 頁: 24556-24559   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  92. Mechanism for the Precipitation of Carbon on the surface of an Ni Catalyst 査読有り

    Tomoharu Tokunaga, Hiroki Tasugi, Natsuki Iwamoto, Katsuhiro Sasaki, Takahisa Yamamoto

    AMTC Letters   4 巻   頁: 60-61   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  93. Domain Structure of LSAT Single Crystal 査読有り

    Shunsuke Okada, Katsuhiro Sasaki, Tomoharu Tokunaga, Satoshi Kobayashi, Takahisa Yamamoto

    AMTC Letters   4 巻   頁: 34-35   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  94. Yttrium Segregation Behavior to Necks during Sintering in Aluminum Doped with Yttria 査読有り

    Tomoya Sako, Tomoharu Tokunaga, Katsuhiro Sasaki, Hiroaki Yoshida, Takahisa Yamamoto

    AMTC Letters   4 巻   頁: 36-37   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  95. Atomic Observation of Catalysis-Induced Nanopore Coarsening of Nanoporous Gold 査読有り

    Takeshi Fujita, Tomoharu Tokunaga, Ling Zhang, Dongwei Li, Luyang Chen, Shigeo Arai, Yuta Yamamoto, Akihiko Hirata, Nobuo Tanaka, Yi Ding, Mingwei Chen

    Nano Letters   14 巻 ( 3 ) 頁: 1172-1177   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  96. In Situ TEM Observation of Double-Wall TiO2 Nanotube 査読有り

    Chaorui Xue, Takashi Narushima, Yohei Ishida, Tomonaru Tokunaga, Tetsu Yonezawa

    Chemistry Letters   43 巻 ( 9 ) 頁: 1514-1516   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  97. Fabrication of tin-filled carbon nanofibres by microwave plasma vapour deposition and their in situ heating observation by environmental transmission electron microscopy 査読有り

    Tomoharu Tokunaga, Takumi Kanematsu, Takafumi Ito, Takahisa Ota, Yasuhiko Hayashi, Katsuhiro Sasaki, Takahisa Yamamoto

    Nanoscale Research Letters   8 巻   頁: 302(1)-302(7)   2013年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  98. Microstructural analysis of thermal degradation of palladium-coated niobium membrane 査読有り

    Katsuhiro Sasaki, Masashi Hattori, Kentaro Tsuchimoto, Hiroshi Yukawa, Shigeo Arai, Tomoharu Tokunaga, Yoshinori Murata, Takahisa Yamamoto

      573 巻   頁: 192-197   2013年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  99. Fabrication of metal nanoparticles from metal-filled carbon nanofibers and their size control by heating 査読有り

    Tomoharu Tokunaga, Takumi Kanematsu, Takahisa Ota, Katsuhiro Sasaki, Takahisa Yamamoto, Yasuhiko Hayashi

    Proceedings of Nanotechnology Materials and Devices Conference     頁: 5-8   2013年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  100. Low-cost and large-scale production of high-purity carbon nanohorns by arc in water towards environmental devices 査読有り

    Yasuhiko Hayashi, Toru. Iijima, Takashi Kitamura, Yuji, Uesugi, H. Takahashi1, M. Unten, Tomoharu Tokunaga

    Proceedings of Nanotechnology Materials and Devices Conference     頁: 1-5   2013年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  101. Transmission Electron Microscopy Observation of Nickel-Yttria Stabilized Zirconia Catalyst for Solid Oxide Fuel Cells in Methane Atmosphere 査読有り

    Tomoharu Tokunaga, Hiroki Tasugi, Natsuki Iwamoto, Toshiaki Yamaguchi, Hirohumi Sumi, Yoshinobu Fujishiro, Katsuhiro Sasaki, Takahisa Yamamoto

    ECS Transactions   57 巻 ( 1 ) 頁: 1455-1462   2013年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  102. Growth and structure analysis of tungsten oxide nanorods using environmental TEM 査読有り

    Tomoharu Tokunaga, Tadashi Kawamoto, Kenta Tanaka, Naohiro Nakamura, Yasuhiko Hayashi, Katsuhiro Sasaki, Kotaro Kuroda, Takahisa Yamamoto

    Nanoscale Research Letters   7 巻   頁: 85(1-7)   2012年1月

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  103. Temperature distributions of electron beam-irradiated samples by scanning electron microscopy 査読有り

    Tomoharu Tokunaga, Takashi Narushima, Tetsu Yonezawa, Takayuki Sudo, Shuichi Okubo, Shigeyuki Komatsubara, Katsuhiro Sasaki, Takahisa Yamamoto

    Journal of Microscopy     頁: in-press   2012年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  104. High temperature in-situ observations of multi-segmented metal nanowires encapsulated within carbon nanotubes by in-situ filling technique 査読有り

    Yasuhiko Hayashi, Tomoharu Tokunaga, Toru Iijima, Takuya Iwata, Golap Kalita, Masaki Tanemura, Katsuhiro Sasaki, Kotaro Kuroda

    Nanoscale Research Letters     頁: inpress   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  105. Atomic origins of the high catalytic activity of nanoporous gold 査読有り

    Takeshi Fujita, Pengfei Guan, Keith McKenna, Xingyou Lang, Akihiko Hirata, Ling Zhang, Tomoharu Tokunaga, Shigeo Arai, Yuta Yamamoto, Nobuo Tanaka, Yoshifumi Ishikawa, Naoki Asao, Yoshinori Yamamoto, Jonah Erlebacher and Mingwei Chen

    Nature materials   11 巻   頁: 775-780   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  106. In-situ ETEM Observation of Change in CaO Powder Composition by High-humidity Gas 査読有り

    Tomoharu Tokunaga, Keishi Kimura, Hiromoto Tasugi, Katsuhiro Sasaki, Takahisa Yamamoto

    AMTC Letters   3 巻   頁: 88-89   2012年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  107. A method for Accurate Temperature Measurement Using Infrared Thermal Camera 査読有り

    Tomoharu Tokunaga, Takashi Narushima, Tetsu Yonezawa, Takayuki Sudo, Shuichi Okubo, Shigeyuki Komatsubara, Katsuhiro Sasaki, Takahisa Yamamoto

    Journal of Electron Microscopy   0 巻   頁: 1-5   2012年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  108. Observation of microstructural changes in polymer-coated Kompeito-type platinum particles by in situ heating TEM 査読有り

    Takashi Narushima, Makino T, Tomoharu Tokunaga,Tetsu Yonezawa

    Journal of Nanoscience and Nanotechnology   12 巻 ( 3 ) 頁: 2612-2616   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  109. Fabrication of Ge nanoneedles by ion-irradiation method 査読有り

    Ako Miyawaki, M. Zamri, T. Hayashi, Y. Hayashi, M. Tanemura, T. Tokunaga

    Surf. and Coat. Tech.     頁: inpress   2011年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  110. Direct Growth of Horizontally Alligned Carbon Nanotubes between Electrodes and Its Application to Field-Effect Transistors 招待有り 査読有り

    Y. Hayashi, B. Jand, T. Iijima, T. Tokunaga, A. Hayashi, M. Tanemura, G. A. J. Amaratunga

    J. Nanosci. Nanotechnol     頁: inpress   2011年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  111. The growth and characterization of Zn nanowires covered with ZnO using plasma-assisted molecular beam irradiation 査読有り

    T. Tokunaga, T Iijima, B Jang, Y. Hayashi, M. Tanemura, K. Sasaki, K. Kuroda

    Proceedings of IEEE INEC 2011     頁: 102   2011年5月

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  112. Growth and structure analysis of tungsten oxide nanorods using environmental TEM 査読有り

    T. Tokunaga, T Kawamoto, K. Tanaka, N. Nakamura, Y. Hayashi, K. Sasaki, K. Kuroda

    Proceedings of IEEE INEC 2011     頁: 62   2011年5月

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  113. *In-situ TEM observation of internal metal inside metal filled carbon fiber 査読有り

    T. Tokunaga, Y. Horita, T. Kanematsu, I. Nomura, Y. Hayashi, K. Kuroda

    Diamond and Related Materials   20 巻 ( 2 ) 頁: 210-212   2011年3月

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  114. TEM observation of structure and growth of the tungsten oxide nanorods 査読有り

    T. Tokunaga, T. Kawamoto, K. Tanaka, Y. Hayashi, K. Sasaki, K. Kuroda

    AMTC Letters   2 巻   頁: 80-81   2010年6月

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  115. Investigation of sample heater material for super high temperature in-situ TEM observation in oxygen existing atmosphere 査読有り

    T. Tokunaga, K. Kimura, D. Kotani, K. Sasaki, K. Kuroda

    AMTC Letters   2 巻   頁: 92-93   2010年6月

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  116. TEM characterization of sintered copper nanoparticles covered by biopolymer nanoskin 査読有り

    K. Ida, K. Sasaki, Y. Sugiyama, Y. Chujo, T. Tokunaga, M. Tomonari, T. Yonezawa, K. Kuroda

    AMTC Letters   2 巻   頁: 88-89   2010年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  117. Synthesis and characterization of carbon nanotube grown on flexible and conducting carbon fiber sheet for field emitter 査読有り

    Yasuhiko Hayashi, K. Suzuki, B. Jang, T. Tokunaga, H. Matsumoto, M. Tanemura, A. Tanioka, G.A.J. Amaratunga

    Diamond and Related Materials   18 巻 ( 2-3 ) 頁: 341-344   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  118. TEMその場観察に用いる加熱体の問題点と検討 招待有り

    徳永智春

    電子顕微鏡によるその場観察と材料への応用展開     頁: 47-52   2009年

     詳細を見る

    担当区分:筆頭著者   記述言語:日本語  

  119. Low-Temperature Fabrication of Ion-Induced Ge Nanostructures: Effect of Simultaneous Al Supply 査読有り

    Ako Miyawaki, Toshiaki Hayashi, Masaki Tanemura, Yasuhiko Hayashi, Tomoharu Tokunaga

    IEICE TRANS. ELECTRON.   E92-C 巻 ( 12 ) 頁: 1417-1420   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  120. Silicon oxide whisker formation during in-situ oxidation of CuO and Si compounds in transmission electron microscopy

    S. Arai, M. Fuzita, D. Kotani, T. Tokunaga, T. Yonezawa, T. Kamino, K. Kuroda

      1 巻   頁: 258-259   2008年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  121. Microstructure and local magnetic induction of segmented and alloyed Pd/Co nanocomposites encapsulated inside vertically aligned multiwalled carbon nanotubes 査読有り

    Yasuhiko Hayashi, T. Fujita, Tomoharu Tokunaga, Kenji Kaneko, Masaki Tanemura, T. Butler, N. Rupesinghe, J. D. Carey, S. R. P. Silva, K. B. K. Teo, G. A. J. Amaratunga

    Diamond and Related Materials   17 巻 ( 7-10 ) 頁: 1525-1528   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  122. Low-Temperature fabrication of Ge nanostructures by ion irradiation 査読有り

    A. Miyawaki, Y. Sugita, K. Yamaguchi, T. Hayashi, Y. Hayashi, T. Tokunaga

    Trans. Mater. Soci. Jpn   33 巻   頁: 1015-1018   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  123. Microstructure and mechanical properties of aluminum fullerene composite fabricated by high pressuretorsion 査読有り

    Tomoharu Tokunaga, Kenji Kaneko, Keisuke Sato, Zenji Horita

    Scripta Materialia   58 巻 ( 9 ) 頁: 735-738   2008年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  124. *Production of aluminum-matrix carbon nanotube composite using high pressure torsion 査読有り

    Tomoharu Tokunaga, Kenji Kaneko, Zenji Horita

    Materials Science and Engineering: A   490 巻 ( 1-2 ) 頁: 300-304   2008年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  125. *Encapsulation of segmented Pd-Co nanocomposites into vertically aligned carbon nanotubes by plasma-hydrogen-induced demixing 査読有り

    Takeshi Fujita, Yasuhiko Hayashi, Tomoharu Tokunaga, T. Butter, N. L. Rupesinghe

    Applied Physics Letter   90 巻   頁: 133116   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  126. Facile fabrication and structural studies of filtrated Ge nanowires from aged Al-Ge alloy 査読有り

    Keisuke Sato, Kenji Kaneko, Tomoharu Tokunaga, Yasuhiko Hayashi, Zenji Horita

    Scripta Materiallia   57 巻 ( 3 ) 頁: 281-284   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  127. Demixing of Solid-Soluted Co–Pd Binary Alloy Induced by Microwave Plasma Hydrogen Irradiation Technique 査読有り

    Tomoharu Tokunaga, Yasuhiko. Hayashi, Takeshi Fujita, S. R. P. Silva, G. A. J. Amaratunga

    Japanese Journal of Applied Physics   45 巻 ( 32 ) 頁: L860–L863   2006年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  128. *Cobalt nanorods fully encapsulated in carbon nanotube and magnetization measurement by off-axis electron holography 査読有り

    Takeshi Fujita, Yasuhiko Hayashi, Tomoharu Tokunaga, Kazuhisa Yamamoto

    Applied Physics Letter   84 巻   頁: 243118   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  129. Fabrication and analysis of Aluminum and Carbon Nanotube Composites Using High Pressure Torsion

    Tomoharu Tokunaga, Kenji Kaneko, Zenji Horita

    Proceedings of The 2nd International Symposium on FunctionalInnovation of Molecular Informatics     頁: 66   2006年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  130. Effect of Thermal Annealing and Oxidative Purification on Multi Wall Carbon Nanotube 査読有り

    Tomoharu Tokunaga, Ichihito Narita, Yasuhiko Hayashi, Kenji Kaneko, Zenji Horita

    Proceedings of The 16th International Microscopy Congress     頁: 158   2006年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  131. Aluminum and Carbon Nanotube Composites Fabricated Using High Pressure Torsion Process

    Tomoharu Tokunaga, Kenji Kaneko, Zenji Horita

    Proceedings of NT06 7th International Conference on The Science Application of Nanotubes     頁: 297   2006年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  132. *Characterization of transport properties of multiwalled carbon nanotube networks by microwave plasma chemical vapor deposition 査読有り

    Yasuhiko Hayashi, Tomoharu Tokunaga, Kenji Kaneko, Zenji Horita

    Diamond and Related Materials   15 巻   頁: 1138-1142   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  133. Formation and observation of wedge-shape carbon film by chemical vapor deposition method using transmission electron microscopy 査読有り

    Kenji Kaneko, Ryo Nagayama, Koji Inoke, Won Jin Moon, Zenji Horita, Yasuhiko Hayash, Tomoharu Tokunaga

    Scripta Materiallia   52 巻   頁: 1205-1209   2005年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  134. Ion Implantation Effects of Microcrystalline and Nanocrystalline Diamond Thin Films 査読有り

    Kannan L. Narayanan, Tetsuo Soga, Tomoharu Tokunaga, Masafumi Yamaguchi

    Japanese Journal of Applied Physics   43 巻 ( 12 ) 頁: 7971-7975   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  135. Corn-shape carbon nanofibers with dense graphite synthesized by microwave plasma-enhanced chemical vapor deposition 査読有り

    Yasuhiko Hayashi, Tomoharu Tokunaga, Tetsuo Soga, Takashi Jimbo, Yuki Yogata, Shoichi Toh

    Applied Physics Letters   84 巻   頁: 2886-2888   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  136. Synthesis of corn-shape carbon nanofibers on Si and Mo substrates by bias-enhanced microwave plasma chemical vapor deposition 査読有り

    Yasuhiko Hayashi, Tomoharu Tokunaga, Yuki Yogata, Shoichi Toh, Kenji Kaneko, Tetsuo Soga

    Diamond and Related Materials   13 巻 ( 4-8 ) 頁: 1198-1202   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  137. Microstructure of metal-filled carbon nanotubes 査読有り

    Toh Shoichi, Kenji Kaneko, Yasuhiko Hayashi, Tomoharu Tokunaga, Won-Jin Moon

    Journal of Electron Microscopy   53 巻 ( 2 ) 頁: 149-155   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

▼全件表示

書籍等出版物 4

  1. まてりあ 査読有り

    徳永智春( 担当: 単著 ,  範囲: 1-2 汎用走査型電子顕微鏡を用いた組織観察(続き))

    日本金属学会  2021年6月 

     詳細を見る

    総ページ数:8   担当ページ:351-358   記述言語:日本語 著書種別:教科書・概説・概論

    DOI: doi:10.2320/materia.60.351

  2. まてりあ 査読有り

    徳永智春( 担当: 単著 ,  範囲: 1-2 汎用走査型電子顕微鏡を用いた組織観察)

    日本金属学会  2021年3月 

     詳細を見る

    総ページ数:9   担当ページ:225-233   記述言語:日本語 著書種別:教科書・概説・概論

  3. 金属ナノ粒子の合成/構造制御とペースト化および最新応用展開

    徳永智春( 担当: 単著 ,  範囲: 第三章第二節)

    R&D出版  2020年12月 

     詳細を見る

    総ページ数:354   担当ページ:137-148   記述言語:日本語 著書種別:教科書・概説・概論

  4. 金属ナノ・マイクロ粒子の最新技術と応用

    米澤 徹, 武仲能子, 是津信行, 手嶋勝弥, 佐藤進, 徳永智春, 他 ( 担当: 共著)

    シーエムシー出版  2013年11月  ( ISBN:978-4-7813-0827-2

     詳細を見る

    記述言語:日本語

MISC 1

  1. LSAT: (La0.3Sr0.7)(Al0.65Ta0.35)O3単結晶のBサイト秩序構造 査読有り

    山本剛久, 徳永智春, 小林俊介  

    まてりあ58 巻 ( 2 ) 頁: 93 - 93   2019年2月

     詳細を見る

    記述言語:日本語  

    DOI: 10.2320/materia.58.93

講演・口頭発表等 51

  1. 電子線照射下のガス環境中に形成されるイオン環境 招待有り

    徳永智春

    その場観察分科会 2021年研究討論会  2021年10月22日  日本顕微鏡学会

     詳細を見る

    開催年月日: 2021年10月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    開催地:オンライン   国名:日本国  

  2. Photoluminescence property control of Ga2O3 by flash sintering 国際会議

    T. Tokunaga、R. Ono 、A. Kodaira、 H. Yoshida 、T. Yamamoto

    The XVIIIth Conference of the European Ceramic Society  2023年7月6日 

     詳細を見る

    開催年月日: 2023年7月

    記述言語:英語   会議種別:口頭発表(一般)  

  3. フラッシュ焼結法を用いた Ga2O3焼結体の作製と蛍光特性制御 招待有り

    徳永 智春 、小平 亜侑 、大野 稜之丞 、吉田 英弘 、山本 剛久

    粉体粉末冶金協会 2023年 春季大会  2023年6月6日 

     詳細を見る

    開催年月日: 2023年6月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

  4. 電子線照射下のガス環境に形成されるイオン環境とその影響 招待有り

    徳永智春

    ナノ学会第21回大会  2023年5月12日 

     詳細を見る

    開催年月日: 2023年5月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

  5. 電子線照射によりガス環境TEM内に発生するイオンと活性元素 招待有り

    徳永智春

    応用物理学会 名古屋大学 スチューデントチャプター  2022年12月10日  応用物理学会 名古屋大学SC 事務局

     詳細を見る

    開催年月日: 2022年12月

    記述言語:日本語  

    開催地:名古屋大学  

  6. 電子顕微鏡内プラズマ環境を利用したクロム酸化物窒化反応

    徳永智春,河上 匠, 樋口 公孝,山本 悠太,山本 剛久

    日本顕微鏡学会 第77回学術講演会  2021年5月13日  日本顕微鏡学会

     詳細を見る

    開催年月日: 2021年5月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:オンライン   国名:日本国  

  7. 不均一組成ALD-AlOx薄膜におけるSTEM-EELS解析

    大川原彩恵、徳永智春、山本剛久

    顕微鏡学会第62回シンポジウム  2020年11月  日本顕微鏡学会

     詳細を見る

    開催年月日: 2020年11月

    記述言語:日本語   会議種別:ポスター発表  

    開催地:オンライン  

  8. ガス環境TEM内に発生するイオンと活性元素発生の可能性

    徳永智春,川上 匠,樋口公孝,山本悠太,山本剛久

    顕微鏡学会第62回シンポジウム  2020年11月  日本顕微鏡学会

     詳細を見る

    開催年月日: 2020年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:オンライン   国名:日本国  

  9. ガス環境TEM内に形成されるイオン環境の解析と窒素イオンによる金属の窒化反応

    徳永智春,樋口公孝,山本悠太,川上 匠,山本剛久

    顕微鏡学会第76回講演会  日本顕微鏡学会

     詳細を見る

    開催年月日: 2020年6月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:オンライン   国名:日本国  

  10. カーボンナノファイバー内部空間に閉じ込められた金属の特性変化 招待有り

    徳永智春

    分子研研究会 表面科学の最先端技術と分子科学~第7回 真空・表面科学若手研究会~ 

     詳細を見る

    開催年月日: 2016年12月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:愛知,分子科学研究所 明大寺キャンパス   国名:日本国  

  11. 液中プラズマ法を用いた酸化チタンナノ粒子の作製と評価

    徳永 智春,元兼 康智, Nguyen Thanh Mai, 石田 洋平, 米澤 徹, 佐々木 勝博, 山本 剛久

    金属学会2016秋期講演大会 

     詳細を見る

    開催年月日: 2016年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  12. SOFC燃料極における炭素析出メカニズムの解明と水素生成用炭素触媒の可能性 招待有り 国際会議

    徳永智春

    SPring-8 Seminar(第253回) 

     詳細を見る

    開催年月日: 2016年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  13. TEMやSTEMを使ってみよう。 招待有り

    徳永智春

    北海道大学材料科学専攻 マテリアルセミナー 

     詳細を見る

    開催年月日: 2015年1月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  14. カーボンブラック触媒の可能性

    徳永智春

    北海道大学材料科学専攻 マテリアルセミナー 

     詳細を見る

    開催年月日: 2014年2月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    開催地:北海道大学   国名:日本国  

  15. Transmission Electron Microscopy Observation of Nickel-Yttria Stabilized Zirconia Catalyst for Solid Oxide Fuel Cells in Methane Atmosphere 国際会議

    Tomoharu Tokunaga, Hiroki Tasugi, Natsuki Iwamoto, Toshio Yamaguchi, Hirohumi Sumi, Yuki Fujishiro, Katsuhiro Sasaki, Takahisa Yamamoto

    SOFC 13 

     詳細を見る

    開催年月日: 2013年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  16. Fabrication of Metal Nanoparticle from Metal Filled Carbon Nanofibers and Their Size Control by Heating 国際会議

    Heating, Tomoharu Tokunaga, Takumi Kanematsu, Takahisa Ota, Yasuhiko Hayashi,

    IEEE NMDC 2013 

     詳細を見る

    開催年月日: 2013年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  17. Low-cost and large-scale production of high-purity carbon nanohorns by arc in water towards environmental devices 国際会議

    Yasuhiko Hayashi1, Toru. Iijima, Takashi Kitamura, Yuji, Uesugi, H. Takahashi1, M. Unten, Tomoharu Tokunaga

    IEEE NMDC 2013 

     詳細を見る

    開催年月日: 2013年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:台湾  

  18. Fabrication of Tin-Doped Carbon Nanofibres by MPCVD for Use as Hydrogen Storage Material and Their Observation by ETEM 国際会議

    Tomoharu Tokunaga, Takumi Kanematsu, Takafumi Ito, Yasuhiko Hayashi, Katsuhiro Sasaki, Takahisa Yamamoto

    International Conference on Diamond and Carbon Materials 2012 

     詳細を見る

    開催年月日: 2012年9月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:スペイン  

  19. ニッケル粒子の透過顕微鏡内ガス導入サイクル過程の観察

    徳永智春,田杉浩基,岩本夏樹,山口十志明,鷲見裕史,佐々木勝寛,山本剛久

    日本金属学会2012年春期大会 

     詳細を見る

    開催年月日: 2012年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  20. 放射温度カメラの電子顕微鏡への利用

    徳永智春

    北海道大学-産総研 研究会 「ナノ界面を用いるサイエンスとその解析に関する研究会」 

     詳細を見る

    開催年月日: 2012年1月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  21. Development of in-situ observation technology for evaluation of SOFC anode Materials by environmental transmission electron microscope 国際会議

    MRS Fall Meeting & Exhibit 

     詳細を見る

    開催年月日: 2011年11月

    記述言語:英語   会議種別:ポスター発表  

    国名:日本国  

  22. 透過電子顕微鏡による材料創製からデバイスへの応用までの工程に関する研究

    中村直寛,徳永智春,佐々木勝寛,山本剛久

    若手セラミスト懇話会 夏季セミナー 

     詳細を見る

    開催年月日: 2011年6月 - 2011年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  23. MgO-C耐火物の透過電子顕微鏡内ガス中高温その場観察

    田杉浩基,木村圭志,徳永智春,佐々木勝寛,黒田光太郎,山本剛久, 竹内宏典,山本雅章,後藤 潔

    若手セラミスト懇話会 夏季セミナー 

     詳細を見る

    開催年月日: 2011年6月 - 2011年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  24. The Growth and Characterization of Zn Nanowires Covered with ZnO using Plasma-assisted Molecular Beam Irradiation 国際会議

    T. Tokunaga, K. Sasaki, K. Kuroda, T. Iijima, B. Jang, Y. Hayashi, R. A. Afre, M. Tanemura

    IEEE International Nano Electronic Conference 

     詳細を見る

    開催年月日: 2011年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  25. Growth and Structure Analysis of Tungsten Oxide Nanorods using Environmental Transmission Electron Microscopy 国際会議

    Tomoharu Tokunaga, Tadashi Kawamoto, Kenta Tanaka, Naohiro Nakamura, Katsuhiro Sasaki, Kotaro Kuroda, Yasuhiko Hayashi

    IEEE International Nano Electronic Conference 

     詳細を見る

    開催年月日: 2011年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  26. 酸素雰囲気中その場加熱TEM用ワイヤーヒーターの検討 国際会議

    徳永智春,小谷大介,木村圭志,佐々木勝寛,黒田光太郎

    日本顕微鏡学会 第67回学術講演会 

     詳細を見る

    開催年月日: 2011年5月

    記述言語:英語   会議種別:口頭発表(一般)  

    国名:日本国  

  27. 加熱SEMのための試料温度測定の試み

    徳永智春,米澤 徹,須藤 孝行,大久保 修一,小松原 成介

    日本顕微鏡学会 第67回学術講演会 

     詳細を見る

    開催年月日: 2011年5月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  28. The Investigation for Growth Mechanism of Tungsten Oxide Nanorods Using Environmental TEM 国際会議

    Tadashi Kawamoto, Kenta Tanaka, Naohiro Nakamura, Tomoharu Tokunaga, Katsuhiro Sasaki, Kotaro Kuroda

    The 4th International Workshop on Advanced Ceramics 

     詳細を見る

    開催年月日: 2010年12月

    記述言語:英語   会議種別:ポスター発表  

    国名:日本国  

  29. Growth and Structure Analysis of Tungsten Oxide Nanorods using Environmental TEM 国際会議

    Tomoharu Tokunaga, Tadashi Kawamoto, Kenta Tanaka, Katsuhiro Sasaki, Kotaro Kuroda

    8th International Vacuum Electron Sources Conference and Nanocarbon 

     詳細を見る

    開催年月日: 2010年10月

    記述言語:英語   会議種別:ポスター発表  

    国名:日本国  

  30. 金属充填カーボ ンナノチューブの高温挙動観察

    兼松 巧,堀田義郎,井藤貴文,野村郁夫,徳永智春,林 靖彦,佐々木勝寛,黒田光太郎

    日本金属学会2010年 秋季(第147回)大会 

     詳細を見る

    開催年月日: 2010年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  31. W酸化物ナノロッドの基板上成長制御

    田中健太,河本規,徳永智春,佐々木勝寛,黒田光太郎

    第40回東海若手セラミスト懇話会 夏期セミナー 

     詳細を見る

    開催年月日: 2010年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  32. 生体由来高分子を被膜した銅ナノ粒子の融着現象のTEM内加熱その場観察

    中條祐貴,杉山康之,井田清信,友成雅則,徳永智春,佐々木勝寛,黒田光太郎

    第40回東海若手セラミスト懇話会 夏期セミナー 

     詳細を見る

    開催年月日: 2010年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  33. タングステン酸化物ナノロッドの基板上成長制御

    田中健太,河本規,徳永智春,佐々木勝寛,黒田光太郎

    第40回東海若手セラミスト懇話会 夏期セミナー 

     詳細を見る

    開催年月日: 2010年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  34. 金属充填カーボンナノチューブの高温挙動に関する研究

    兼松 巧,野村郁夫,徳永智春,佐々木勝寛,林 靖彦

    第40回東海若手セラミスト懇話会 夏期セミナー 

     詳細を見る

    開催年月日: 2010年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  35. In-situ TEM observation of internal metal inside metal filled carbon fiber 国際会議

    Tomoharu Tokunaga, Yoshiro Horita, Takumi Kanematsu, Ikuo Nomura, Toru Iijima, Yasuhiko Hayashi, 1Kotaro Kuroda

    4th International Conference on New Diamond and Nano Carbons 

     詳細を見る

    開催年月日: 2010年5月

    記述言語:英語   会議種別:ポスター発表  

    国名:中華人民共和国  

  36. TEMその場観察に用いる加熱体の問題点と検討

    徳永智春

    電子顕微鏡によるその場観察と材料への応用展開 

     詳細を見る

    開催年月日: 2009年11月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  37. アルミニウム-カーボンナノ材料複合材料の創製に関する基礎研究

    東海若手セラミスト懇話会 夏季セミナー 

     詳細を見る

    開催年月日: 2009年7月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  38. Growth of the tungsten oxide nanorods: an in-situ TEM observation study 国際会議

    Focused on the application of Electron Microscopy in the field of Materials Science. 

     詳細を見る

    開催年月日: 2009年

    記述言語:英語   会議種別:ポスター発表  

    国名:日本国  

  39. 酸素雰囲気中におけるタングステン発熱体の試料への蒸着

    徳永智春, 小谷大介, 佐々木勝寛, 黒田光太郎

    日本金属学会 2009年 春季大会 

     詳細を見る

    開催年月日: 2009年

    記述言語:日本語  

    国名:日本国  

  40. Fablication and analysis of Aluminum and Carbon Nanotube Composites Using High Pressure Tortion

    The 2nd International Symposium on Functional Innovation of Molecular Informatics 

     詳細を見る

    開催年月日: 2006年10月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  41. 加熱を要しないAl-単層カーボンナノチューブの複合化

    徳永智春,金子賢治,堀田善治

    日本金属学会 2006年 秋季大会 

     詳細を見る

    開催年月日: 2006年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  42. Effect of Thermal Annealing and Oxidative Purification on Multi Wall Carbon Nanotube 国際会議

    The 16th International Microscopy Congress 

     詳細を見る

    開催年月日: 2006年9月

    記述言語:英語   会議種別:ポスター発表  

    国名:日本国  

  43. Creation and Analysis of Aluminum and Carbon Nanotube Composites Using High Pressure Tortion Process

     詳細を見る

    開催年月日: 2006年7月

    記述言語:英語   会議種別:ポスター発表  

    国名:日本国  

  44. Aluminum and Carbon Nanotube Composites Fabricated Using High Pressure Torsion Process 国際会議

     詳細を見る

    開催年月日: 2006年6月

    記述言語:英語  

  45. 高圧回転歪み法を用いたAl-単層カーボンナノチューブ複合材料の作成

    徳永智春,金子賢治,堀田善治

    鉄鋼協会・日本金属学会合同学術講演大会 

     詳細を見る

    開催年月日: 2006年6月

    記述言語:日本語   会議種別:口頭発表(一般)  

  46. 欠陥を含んだグラファイト層が多層カーボンナノチューブの電気伝導特性に与える影響

    徳永智春,成田一人,金子賢治,林 靖彦

     詳細を見る

    開催年月日: 2005年12月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  47. 欠陥を含んだグラファイト層が多層カーボンナノチューブの電気伝導特性に与える影響

    徳永智春,成田一人,金子賢治,林 靖彦

    日本顕微鏡学会第50回シンポジウム 

     詳細を見る

    開催年月日: 2005年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  48. マイクロ波プラズマCVD法による金属充填カーボンナノチューブの成長と特性

    徳永智春,藤 昇一,金子賢治,林 靖彦

    日本顕微鏡学会第50回シンポジウム 

     詳細を見る

    開催年月日: 2005年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  49. 様々な温度下での多層カーボンナノチューブネットワークの電気的特性

    徳永智春, 渡邉 啓, 加藤 理, 林 靖彦, 藤 昇一, 金子賢治

    フラーレン・ナノチューブ研究会 

     詳細を見る

    開催年月日: 2004年7月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

  50. マイクロ波プラズマCVD法による金属内包カーボンナノチューブの成長と特性

    フラーレン・ナノチューブ研究会 

     詳細を見る

    開催年月日: 2004年1月

    記述言語:日本語   会議種別:ポスター発表  

    国名:日本国  

    徳永智春, 渡邉 啓, 加藤 理, 林 靖彦, 藤 昇一, 金子賢治

  51. 先端がコーン状のカーボンナノファイバーの成長と評価

    徳永智春, 与我田雄樹, 林 靖彦, 藤 昇一, 金子賢治, 曽我哲夫, 神保孝志

    応用物理学会 第64回 

     詳細を見る

    開催年月日: 2003年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

▼全件表示

共同研究・競争的資金等の研究課題 4

  1. 温度と雰囲気を制御したTEM内部におけるDLCその場観察

    2009年4月 - 2010年3月

    企業からの受託研究 

      詳細を見る

    自動車産業を中心に摺動部への適用が進んでいるDLC膜に関して、その耐環境特性の把握とより詳細な材料開発指針を得る為に、環境温度が変化した時の膜構造変化をTEMによって分析・解明する。

  2. 自己整合技術を用いた有機光テープモジュールの開発

    2008年4月 - 2010年3月

    中部経済産業局 

      詳細を見る

    資金種別:競争的資金

  3. カーボンナノチューブを用いた電子放出特性の研究

    2008年4月 - 2009年3月

    企業からの受託研究 

      詳細を見る

    CNTを用いた画像デバイスの輝度を向上させる目的で、表面にチタン酸化物を蒸着したCNTを作成し、その構造解析を行った。その結果、チタン酸化物を10nm蒸着したCNTは蒸着物に厚く埋もれ確認されなかったが、1nmの蒸着ではCNTの特徴である中空構造を維持した状態で蒸着されたことが明らかになった。しかし、蒸着の影響のためかCNTの結晶性が低下していた。

  4. 自己整合技術を用いた有機光高度機能部材の開発

    2005年4月 - 2007年3月

    中部経済産業局 

      詳細を見る

    資金種別:競争的資金

    大面積化可能、超軽量、省スペース、フレキシブル等の特徴を有する有機デバイスの研究開発が活発化している。その高度化の手法として、我々はアライメント余裕無く作製できる自己整合有機トランジスタ、簡単作製可能なインクジェットプリント法を用いた自己整合有機EL素子等の新規技術を提案・実現してきた。本開発事業では、この自己整合技術に、新たな有機デバイス作製技術を摺り合わせ融合することで、低コスト化と大面積化の問題点を克服した有機光高度機能部材を確立する。また、本有機光高度機能部材を複合機能集積化することで、複数の最終商品群の実現を目指すことを目的とする。

科研費 9

  1. 常温焼成可能な銅ナノ粒子導電材料の実現

    研究課題/研究課題番号:23K17855  2023年6月 - 2025年3月

    科学研究費助成事業  挑戦的研究(萌芽)

    米澤 徹, 見山 克己, 徳永 智春

      詳細を見る

    担当区分:研究分担者 

    銅は容易に酸化し、粒子を小さくすると酸化防止のために大量の有機保護剤を加える必要がある。そのため、銀のようにナノサイズ化による低温焼結はできない。そこで研究代表者が世界で初めて合成に成功した準安定微酸化物Cu64Oナノ粒子を用いる。この粒子はさらなる酸化が空気中で容易に起こらず、比較的安定である。これを加熱すると、60℃程度で金属銅に還元され、その際の結晶構造の変化から銅原子の大きな拡散が生じ、結晶子を大きくする。その結果、100℃以下での導電性銅被膜の形成、低温での接合材料への利用可能性が高いと考えられる。そこで、この銅原子拡散現象の解明を行い、Cu64Oナノ粒子の実用可能性を探求する。

  2. 微酸化銅粒子と低温還元反応を利用したナノ銅吹き出しによる迅速焼結導電膜形成

    研究課題/研究課題番号:19K22094  2019年6月 - 2021年3月

    日本学術振興会  科学研究費助成事業  挑戦的研究(萌芽)

    米澤 徹, グエン タンマイ, 徳永 智春, 塚本 宏樹

      詳細を見る

    担当区分:研究分担者 

    焼結用配線板としてポリマーベースフィルムを用いてその上に銅ナノ粒子・微粒子ペーストを印刷し、焼結させてフレキシブル銅配線フィルムを形成する。このベースフィルムは銅との熱膨張率差が小さい延伸ポリエステルフィルムややや高温での焼結実験の場合にはポリイミドフィルムを用いる。塗工はスクリーン印刷で行い、塗工厚はスクリーン線径により決定する。配線パターン分析、クロスカット評価による密着度測定、マイグレーション耐性試験、曲げ試験などを行い評価し、実用性を検証する。
    本研究では、低温焼成用銅微粒子として、Cu8O以上の微酸化銅ナノ粒子や微酸化相を表層にもつ銅微粒子およびその混合体を合成した。この数十g/バッチ以上得られる工業的合成法を確立した。得られた微粒子・ナノ粒子をジプロピレングリコールなどにビーズミルや旋回法を用いて分散した。分散条件を最適化し、安定なペーストを合成できた。これは半年以上用いることができる。銅微粒子の含有量を80 wt%以上にできた。これを基板に塗布し、200℃以下で焼結させたところ、バルクの数倍以内の低い抵抗率を示す安定な導電被膜の形成に成功した。さらにその被膜形成機構が、原子の拡散強化である「ナノ銅吹き出し」によることを示した。
    本研究では、銅微粒子の焼結において微酸化相(Cu2OやCuOではなく、酸素比率の少ない酸化物相)の利用を検討し、それが低温で金属銅へ変換し焼結することが可能であることを示した。その際、結晶構造が変化することから銅原子が通常よりも大きく拡散することが期待される。実際の観測結果はそれを支持しその結果は高い学術的意義がある。これは、粒子同士の接合、ネッキング形成が容易になることを示し、高い導電性を持つ被膜の低温形成に役立つ。実際の観測結果もそれを支持しており、こうした結果は、銅微粒子の導電材料、接合材料への応用に大きな一歩を示した点で社会的意義が大きい。また、微酸化銅の材料化も本研究が世界初である。

  3. 超広帯域光源開発のためのナノ粒子の最適化

    研究課題/研究課題番号:18KK0159  2018年10月 - 2022年3月

    日本学術振興会  科学研究費助成事業  国際共同研究加速基金(国際共同研究強化(B))

    米澤 徹, グエン タンマイ, 徳永 智春, 塚本 宏樹

      詳細を見る

    担当区分:研究分担者  資金種別:競争的資金

    高強度レーザーパルスと物質、特にコロイドである水分散液を含むナノ粒子などの凝縮系との相互作用は、さまざまな非線形光学効果が期待される。本研究では、フェムト秒パルスレーザーを、種々のナノ粒子分散液に照射して、そこから発生するエネルギー線を検知して解析してきた。結果として、金ナノ粒子水分散液からはX線を効率よく取り出すことができ、Cu2O/Cu薄層界面からもTHz波の発光が得られた。また、ZnTeナノ粒子の水分散液からもTHzが高い効率で得られ、こうした、ナノ粒子などの凝縮系と高強度レーザーパルスとの相互作用によって、超広帯域での光を取り出すことが可能であることが示された。
    本研究では、フェムト秒という非常に短いパルスの近赤外領域のレーザーを、種々のナノ粒子分散液に照射し、そこから超広帯域発生するエネルギー線を検知した。金やZnTeナノ粒子、Cu2O/Cu界面を用いることで、プラズマ発生、高次の非線形効果によって、水よりも効率的にアップコンバージョン、ダウンコンバージョンがおこり、光子-光子変換が生じていると考えられる。これによって、超広帯域での光を取り出すデバイスの実現の可能性が生まれた。

  4. ガス環境TEMその場観察法は真に材料とガスとの反応を観察しているのか?

    研究課題/研究課題番号:18K04824  2018年4月 - 2021年3月

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    徳永 智春

      詳細を見る

    担当区分:研究代表者 

    配分額:4420000円 ( 直接経費:3400000円 、 間接経費:1020000円 )

    電子線照射中の窒素ガス雰囲気中には,気体分子のイオン化に伴うイオンと電子が発生していることが明らかになり,発生したイオンはN2+イオンであることが判明した.つまり電子線照射中のガス環境はガスだけではなく,イオンも存在していることを見出した.この雰囲気にCr2O3を保持したところ,窒化されていることが判明した.電子線照射中のガス雰囲気における試料観察はイオンの影響も考慮する必要がある.
    ガスと材料の反応を観察することが可能と考えられてきたガス環境その場観察手法は,ガスと材料の反応だけではなく,電子線照射に伴って発生するイオンとの反応が含まれる可能性が考えられた.ガス環境その場観察から得られた研究成果を再検証する必要があると共に,発生するイオンを除去した環境を形成する必要があると考えられた.

  5. 引張強度6GPaを超える超高強度・超軽量カーボンナノチューブ紡績糸の創製

    研究課題/研究課題番号:18H01708  2018年4月 - 2021年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    林 靖彦, 鶴田 健二, 羽田 真毅, 西川 亘, 徳永 智春

      詳細を見る

    担当区分:研究分担者 

    本研究では,基板の合成した長尺・高密度の数層カーボンナノチューブ(CNT)フォレスから,乾式で紡績法によりCNT長繊維を作製し,実用上ベンチマークとなる炭素繊維の強度を超える引張強度のCNT長繊維の実現を目指した.室温からCNT合成初期の温度までの触媒金属粒子の形状変化を明らかにし,2層CNTを選択的に合成することが可能となった.そして,真空および極簿エタンガス中でCNT長繊維全体に通電加熱することで,残留するアモルファスカーボンの除去とグラフェンへの構造変化が同時に起こっていることを明らかにした.さらにCNT繊維を一方向に配向させる紡績糸技術により,2.5GPaを超える高強度が実現できた.
    本研究は,基板に垂直配向した長尺・高密度カーボンナノチューブ(CNT)フォレストを合成し,この基板から乾式紡績法によりCNT長繊維を作製し,その高強度化する手法を開発するものである.高強度で超軽量の特性を併せ持つCNT紡績糸が実現できると,炭素繊維強化プラスチック(CFRP)代替への応用が期待される.実用途の輸送機器用材料は,温室効果ガス削減のため,軽量化と高強度化が求められており,高強度CNT長繊維の実現は社会,産業基盤へ大きく貢献する.

  6. マトリクススパッタリング法による安定高効率蛍光発光合金ナノ粒子の創製

    研究課題/研究課題番号:18H01820  2018年4月 - 2021年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    米澤 徹, グエン タンマイ, 徳永 智春

      詳細を見る

    担当区分:研究分担者 

    本研究では、多元マグネトロンスパッタ装置を用い、マトリクススパッタリング法によってナノ粒子合成、特に合金ナノ粒子の合成を行った。得られた粒子は安定で、よく分散していた。また、TEMグリッドへの直接スパッタリングなども行った。得られたの微細構造についてXRD、収差補正(原子分解)STEMなどを用いて詳細に行い、物性については、光学物性について検討をした。
    XRDによる結晶構造解析と、STEMによる原子の配置の解析により、得られたナノ粒子は各々が合金であり、固溶体構造をとることが明確となった。これはマトリクススパッタリング法の特徴であった。光学特性についても検討し発光を示した。
    本研究では、単一もしくは複数のターゲットを用いたマトリクススパッタリング法による金属および合金ナノ粒子の合成と物性の検討を行った。得られた合金ナノ粒子の微細構造は固溶体構造であり、こうした手法を確立したことは意義深い。また、その際、XRD、XPS、EDS分析のみならず、STEM-HAADFを用いた原子の配列の検証も行い、微細に決定したことは学術的にも意味がある。また、保護剤分子の官能基や混合比などによって粒子径・構造を制御することを見出した。また発行を示す粒子はその粒子径が変わっても蛍光挙動が変化せず、クラスター集積体構造が蛍光発光を強くしていること見出したことはこれらの材料化に貢献する。

  7. セラミック双結晶の粒界構造ユニット形成の体系化

    研究課題/研究課題番号:26249088  2014年4月 - 2017年3月

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    山本 剛久, 佐々木 勝寛, 徳永 智春, 武藤 俊介

      詳細を見る

    方位関係が異なる結晶が互いに接する結晶粒界には、格子不連続性を緩和する配位多面体が形成される。多結晶体の物性は、この粒界構造と密接に関係する。本課題では、結晶粒界に起因する種々の現象について調べ、その現象と粒界構造との相関について調べた。例えば、電界印加に伴うセラミック圧紛体の急峻な緻密化現象について行った研究では、結晶粒界に優先的に作用する外部電界に起因して、結晶粒界及びその近傍が大気中において強還元状態になること、この効果を利用して大気中において窒化が生じること、粒界還元状態は結晶粒の方位関係に依存することなどをはじめとした成果が得られた。

  8. 環境TEMを用いたタングステン酸化物ナノ構造体の成長メカニズムの解明と成長制御

    2010年4月 - 2013年3月

    科学研究費補助金  若手研究(B)

      詳細を見る

    担当区分:研究代表者 

  9. 透過電子顕微鏡による有機電界効果トランジスタの構造解析と特性向上

    2008年9月 - 2010年3月

    科学研究費補助金  若手スタートアップ 20860041

    徳永智春

      詳細を見る

    担当区分:研究代表者 

▼全件表示

産業財産権 5

  1. 水素製造方法及び水素製造装置

    徳永 智春,影山 健友

     詳細を見る

    出願人:徳永 智春,影山 健友

    出願番号:特願2016-172936  出願日:2016年9月

    出願国:国内  

  2. カーボンナノチューブ複合体及びその製造方法

     詳細を見る

    出願番号:特許出願2006-331078  出願日:2006年12月

    公開番号:特許公開2008-144207 

    出願国:国内  

  3. フラーレン複合体及びその製造方法

     詳細を見る

    出願番号:特許出願2006-331228  出願日:2006年12月

    公開番号:特許公開2008-144208 

    出願国:国内  

  4. 磁性金属内包カーボンナノチューブ素子

    林 靖彦, 徳永智春, 藤田武志

     詳細を見る

    出願人:林 靖彦, 徳永智春, 藤田武志

    出願番号:107470  出願日:2006年

    特許番号/登録番号:4892723  登録日:2012年 

    出願国:国内  

  5. 金属内包カーボンナノチューブの製造方法

     詳細を見る

    出願番号:特許出願2003-344405  出願日:2003年10月

    公開番号:特許公開2005-104814 

    出願国:国内  

 

担当経験のある科目 (本学) 3

  1. マテリアル工学学生実験2

    2020

  2. マテリアル工学学生実験1

    2020

  3. マテリアル工学概論

    2020

担当経験のある科目 (本学以外) 6

  1. Hokkaido Summer Institute

    2022年10月 Hokkaido University)

     詳細を見る

    科目区分:大学院教養科目  国名:日本国

  2. 先端材料

    2022年4月 - 2022年7月 愛知工業大学)

     詳細を見る

    科目区分:学部専門科目  国名:日本国

  3. Hokkaido Summer Institute

    2021年8月 北海道大学)

     詳細を見る

    科目区分:大学院専門科目  国名:日本国

  4. 先端材料

    2021年4月 - 2021年7月 愛知工業大学)

     詳細を見る

    科目区分:学部専門科目  国名:日本国

  5. Hokkaido Summer Institute

    2020年8月 - 2020年9月 Hokkaido University)

     詳細を見る

    科目区分:その他  国名:日本国

  6. 先端材料

    2020年4月 - 2020年7月 愛知工業大学)

     詳細を見る

    科目区分:学部専門科目  国名:日本国

▼全件表示

 

学術貢献活動 1

  1. 東海若手セラミスト懇話会

    役割:企画立案・運営等

    セラミクス協会東海支部  2009年 - 現在

     詳細を見る

    種別:学会・研究会等