Updated on 2024/03/15

写真a

 
TOKUNAGA, Tomoharu
 
Organization
Graduate School of Engineering Materials Design Innovation Engineering 2 Assistant Professor
Graduate School
Graduate School of Engineering
Undergraduate School
School of Engineering Materials Science and Engineering
Title
Assistant Professor
Contact information
メールアドレス

Degree 1

  1. 工学博士 ( 2007.9 ) 

Research Areas 4

  1. Nanotechnology/Materials / Nanomaterials

  2. Nanotechnology/Materials / Structural materials and functional materials

  3. Nanotechnology/Materials / Nanomaterials

  4. Nanotechnology/Materials / Structural materials and functional materials

Research History 5

  1. Nagoya University   Graduate School of Engineering Materials Design Innovation Engineering 2   Assistant Professor

    2017.4

  2. Nagoya University   Graduate School of Engineering Department of Quantum Engineering   Assistant Professor

    2007.10 - 2017.3

  3. 名古屋大学 工学研究科 助教

    2007.10

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    Country:Japan

  4. 名古屋大学 工学研究科 助教

    2007.10

  5. 名古屋大学 工学研究科 助教

    2007.10

Education 2

  1. Kyushu University   Faculty of Engineering

    2005.4 - 2007.9

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    Country: Japan

  2. Nagoya Institute of Technology   Graduate School, Division of Engineering

    2003.4 - 2005.3

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    Country: Japan

Professional Memberships 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

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Committee Memberships 2

  1. 東海若手セラミスト懇話会   運営委員  

    2006.4   

  2. 東海若手セラミスト懇話会   運営委員  

    2006.4   

Awards 1

  1. 第57回金属組織写真賞 奨励賞

    2006   日本金属学会  

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    Country:Japan

 

Papers 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> Reviewed

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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 132 ( 3 ) page: 93 - 98   2024.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2109/jcersj2.23179

    DOI: 10.2109/jcersj2.23179

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

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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 132 ( 2 ) page: 63 - 67   2024.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2109/jcersj2.23170

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

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

    ADVANCED ENGINEERING MATERIALS   Vol. 25 ( 18 )   2023.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1002/adem.202201807

    DOI: 10.1002/adem.202201807

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

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

    JAPANESE JOURNAL OF APPLIED PHYSICS   Vol. 62 ( SG )   2023.6

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.35848/1347-4065/acb65c

    DOI: 10.35848/1347-4065/acb65c

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

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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 131 ( 5 ) page: 135 - 139   2023.5

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2109/jcersj2.23011

    DOI: 10.2109/jcersj2.23011

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  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   Vol. 64 ( 1 ) page: 184 - 190   2023

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

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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 130 ( 12 ) page: 906 - 912   2022.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher: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

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

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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 130 ( 11 ) page: 895 - 898   2022.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher: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

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  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> Reviewed

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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 130 ( 4 ) page: 327 - 330   2022.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher: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

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  10. Crystalline boron monosulfide nanosheets with tunable bandgaps Reviewed

    Kusaka Haruki, Ishibiki Ryota, Toyoda Masayuki, Fujita Takeshi, Tokunaga Tomoharu, Yamamoto Akiyasu, Miyakawa Masashi, Matsushita Kyosuke, Miyazaki Keisuke, Li Linghui, Shinde Satish Laxman, Lima Mariana S. L., Sakurai Takeaki, Nishibori Eiji, Masuda Takuya, Horiba Koji, Watanabe Kenji, Saito Susumu, Miyauchi Masahiro, Taniguchi Takashi, Hosono Hideo, Kondo Takahiro

    JOURNAL OF MATERIALS CHEMISTRY A   Vol. 9 ( 43 ) page: 24631 - 24640   2021.11

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1039/d1ta03307g

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  11. Shrinkage rate control during a flash state by current-ramping for 3 mol% Y2O3-doped ZrO2 polycrystals Reviewed

    Ishino Yuki, Taguchi Kimihiro, Koike Masao, Tokunaga Tomoharu, Yamamoto Takahisa

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   Vol. 104 ( 10 ) page: 4960 - 4967   2021.10

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1111/jace.17912

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  12. Rapid sintering of 3 mol % Y2O3-doped ZrO2 by a combined rapid furnace heating and shrinkage-controlled flash sintering protocol Reviewed

    Ishino Yuki, Taguchi Kimihiro, Kodaira Ayu, Tokunaga Tomoharu, Yamamoto Takahisa

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 129 ( 8 ) page: 551 - 554   2021.8

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2109/jcersj2.21066

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  13. Near complete densification of flash sintered 8YSZ: controlled shrinkage rate effects Reviewed

    Taguchi Kimihiro, Ishino Yuki, Tokunaga Tomoharu, Yamamoto Takahisa

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   Vol. 41 ( 8 ) page: 4567 - 4571   2021.7

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  14. Constant shrinkage rate control during a flash event for 8 mol%Y2O3-doped ZrO2 polycrystals Reviewed

    Taguchi Kimihiro, Ishino Yuki, Tokunaga Tomoharu, Yamamoto Takahisa

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 129 ( 3 ) page: 204 - 207   2021.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2109/jcersj2.20192

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  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   Vol. 68 ( 11 ) page: 482 - 486   2021

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    Publisher: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

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  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   Vol. 68 ( 11 ) page: 487 - 493   2021

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    Publisher: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

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  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   Vol. 9 ( 2 ) page: 678 - 688   2020.1

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    Language:Japanese   Publisher: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

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  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   Vol. 31 ( 6 ) page: 1157 - 1165   2019.5

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    Language:Japanese   Publisher: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

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  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   Vol. 273 ( 1 ) page: 46 - 52   2019.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1111/jmi.12759

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    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   Vol. 2018-January   page: 357 - 361   2018.2

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    Language:Japanese   Publisher: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

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

    Mikito Seko, Shunta Inagaki, Tomoharu Tokunaga, Shunsuke Kobayashi, Atsutomo Nakamura, Takahisa Yamamoto

    Journal of the European Ceramic Society   Vol. 44 ( 5 ) page: 2965 - 2971   2024.5

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jeurceramsoc.2023.12.046

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

    Shunsuke Kayukawa, Yutaro Katsuyama, Ayu Kodaira, Tomoharu Tokunaga, Koji Morita, Atsutomo Nakamura, Takahisa Yamamoto

    Journal of the European Ceramic Society   Vol. 43 ( 14 ) page: 6272 - 6278   2023.11

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jeurceramsoc.2023.06.001

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  23. Near-full compaction within only 30min of total sintering time by shrinkage-rate-controlled flash sintering in 3mol% Y<inf>2</inf>O<inf>3</inf>-doped ZrO<inf>2</inf> polycrystal

    Yuki Ishino, Masao Koike, Ayu Kodaira, Tomoharu Tokunaga, Takahisa Yamamoto

    Journal of the Ceramic Society of Japan   Vol. 131 ( 10 ) page: 600 - 607   2023.10

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    Publishing type:Research paper (scientific journal)  

    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

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  24. Structural Defect Effect on the Concentration Quenching of TbxY2–xO3 Phosphor Thin Films

    Shizuka Suzuki, Takuro Dazai, Tomoharu Tokunaga, Takahisa Yamamoto, Ryuzi Katoh, Ryota Takahashi

    The Journal of Physical Chemistry C   Vol. 127 ( 19 ) page: 9380 - 9387   2023.5

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acs.jpcc.3c01679

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

    Yuen-ting Rachel Chau, Mai Thanh Nguyen, Tomoharu Tokunaga, Tetsu Yonezawa

    Advanced Powder Technology   Vol. 34 ( 4 ) page: 103970 - 103970   2023.4

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.apt.2023.103970

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

    Kohta Nambu, Taisuke Kitaoka, Koji Morita, Kohei Soga, Tomoharu Tokunaga, Takahisa Yamamoto, Hiroshi Masuda, Hidehiro Yoshida

    Journal of the American Ceramic Society   Vol. 106 ( 3 ) page: 2073 - 2082   2023.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    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

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  27. Microcrack healing in single-crystal cubic zirconia by thermal annealing Reviewed

    Shunsuke Kayukawa, Yutaro Katsuyama, Ayu Kodaira, Tomoharu Tokunaga, Koji Morita, Atsutomo Nakamura, Kimitaka Higuchi, Takahisa Yamamoto

    Journal of the European Ceramic Society   Vol. 43 ( 3 ) page: 1078 - 1086   2023.3

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jeurceramsoc.2022.10.065

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  28. A technique to modify the photoluminescence intensity of β-Ga2O3 polycrystals using an electric field during sintering Reviewed

    Ryonosuke Ono, Ayu Kodaira, Tomoharu Tokunaga, Hidehiro Yoshida, Takahisa Yamamoto

    Journal of Luminescence   Vol. 254   page: 119508 - 119508   2023.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jlumin.2022.119508

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

    Shunsuke Tanahashi, Sae Okawara, Tomoharu Tokunaga, Takahisa Yamamoto

    MATERIALS TRANSACTIONS   Vol. 64 ( 1 ) page: 184 - 190   2023.1

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    Publishing type:Research paper (scientific journal)   Publisher:Japan Institute of Metals  

    DOI: 10.2320/matertrans.mt-n2022004

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  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

    Masao Koike, Ayu Kodaira, Tomoharu Tokunaga, Takahisa Yamamoto

    Materials Transactions   Vol. 64 ( 10 ) page: 2315 - 2320   2023

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    Publishing type:Research paper (scientific journal)  

    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

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  31. Apparent Sintering Activation Energy Estimated by Master Sintering Curves for 8 mol% Y&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Doped ZrO&lt;sub&gt;2&lt;/sub&gt; Polycrystals during Shrinkage-Rate Controlled Flash Sintering

    Masao Koike, Ayu Kodaira, Tomoharu Tokunaga, Takahisa Yamamoto

    MATERIALS TRANSACTIONS   Vol. 64 ( 9 ) page: 2315 - 2320   2023

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  32. Variation of photoluminescence intensity depending on the timing of electric field application during isothermal flash sintering for 3mol%Y2O3–ZrO2 polycrystal Reviewed

    Asa Itoh, Tomoharu Tokunaga, Ayu Kodaira, Hidehiro Yoshida, Takahisa Yamamoto

    Ceramics International   Vol. 48 ( 19 ) page: 28712 - 28717   2022.10

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    DOI: 10.1016/j.ceramint.2022.06.185

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  33. Effect of He Buffer Gas on Pulsed Nd:YAG Laser Deposition of EuxY2–xO3 Phosphor Thin Films Reviewed

    Shizuka Suzuki, Takuro Dazai, Kazuhiro Kawashima, Tomoharu Tokunaga, Takahisa Yamamoto, Ryota Takahashi

    ACS Applied Electronic Materials   Vol. 4 ( 9 ) page: 4419 - 4426   2022.9

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    DOI: 10.1021/acsaelm.2c00691

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

    Hideya Kawasaki, Tomoko Otsuki, Fumiya Sugino, Ken Yamamoto, Tomoharu Tokunaga, Rintaro Tokura, Tetsu Yonezawa

    Chemical Communications   Vol. 58 ( 56 ) page: 7741 - 7744   2022.7

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  35. Effect of electron beam irradiation in gas atmosphere during ETEM Reviewed

    Tomoharu Tokunaga, Takumi Kawakami, Kimitaka Higuchi, Yuta Yamamoto, Takahisa Yamamoto

    Micron   Vol. 158   page: 103289 - 103289   2022.7

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    DOI: 10.1016/j.micron.2022.103289

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

    Rintaro Tokura, Hiroki Tsukamoto, Tomoharu Tokunaga, Mai Thanh Nguyen, Tetsu Yonezawa

    Materials Advances   Vol. 3 ( 12 ) page: 4802 - 4812   2022.6

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    1-Hexanoic acid stabilised copper nanoparticles were obtained. Cu<sub>64</sub>O phase could be found on the particle surface. During sintering, the stabilising molecule, 1-hexanoic acid, reduced Cu<sub>64</sub>O to Cu and it introduced neckings between the particles.

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  37. Excess oxygen-vacancy formed by FAST regime of direct-current electric field during flash sintering for 3 mol%–10 mol% Y2O3-doped ZrO2 Reviewed

    Nobuhiro Morisaki, Tomoharu Tokunaga, Kiyoshi Kobayashi, Ayu Kodaira, Takahisa Yamamoto

    Ceramics International   Vol. 48 ( 9 ) page: 12091 - 12097   2022.5

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    DOI: 10.1016/j.ceramint.2022.01.069

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  38. Anelasticity induced by AC flash processing of cubic zirconia Reviewed

    Hiroshi Masuda, Koji Morita, Tomoharu Tokunaga, Takahisa Yamamoto, Hidehiro Yoshida

    Acta Materialia   Vol. 227   page: 117704 - 117704   2022.4

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  39. Anisotropic Growth of Copper Nanorods Mediated by Cl– Ions Reviewed International coauthorship

    Min Jia Saw, Mai Thanh Nguyen, Yuji Kunisada, Tomoharu Tokunaga, Tetsu Yonezawa

    ACS Omega   Vol. 7 ( 8 ) page: 7414 - 7420   2022.3

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  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 Reviewed

    Yoshinori Tokuda, Takeshi Irimoto, Naoki Nishikawa, Yutaro Katsuyama, Shunsuke Kobayashi, Tomoharu Tokunaga, Takahisa Yamamoto

    Surface and Interface Analysis   Vol. 54 ( 3 ) page: 212 - 217   2022.3

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    Herein, we investigated the surface of an (La<sub>0.3</sub>Sr<sub>0.7</sub>)(Al<sub>0.65</sub>Ta<sub>0.35</sub>)O<sub>3</sub> (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.

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

    Haoran Liu, Kai Ikeda, Mai Thanh Nguyen, Susumu Sato, Naoki Matsuda, Hiroki Tsukamoto, Tomoharu Tokunaga, Tetsu Yonezawa

    ACS Omega   Vol. 7 ( 7 ) page: 6238 - 6247   2022.2

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    DOI: 10.1021/acsomega.1c06769

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

    Ze-Xing Cai, Hiromi Goou, Yoshikazu Ito, Tomoharu Tokunaga, Masahiro Miyauchi, Hideki Abe, Takeshi Fujita

    Chemical Science   Vol. 12 ( 34 ) page: 11306 - 11315   2021.9

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    Nanoporous ultra-high-entropy alloys containing 14 elements (Al, Ag, Au, Co, Cu, Fe, Ir, Mo, Ni, Pd, Pt, Rh, Ru, and Ti) were obtained by dealloying. The products showed excellent electrocatalytic performance for water splitting in acidic media.

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  43. Flash sintering for BaTiO<inf>3</inf> with square alternating current field including zero-field duration Invited Reviewed

    Ryosuke Umemura, Tomoharu Tokunaga, Takahisa Yamamoto

    Journal of the Ceramic Society of Japan   Vol. 128 ( 12 ) page: 1018 - 1023   2020.12

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    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.

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  44. H-2 production from methane decomposition by fullerene at low temperature Reviewed

    Tomoharu Tokunaga, Kohei Kuno, Takumi Kawakami, Takahisa Yamamoto, Akitaka Yoshigoe

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   Vol. 45 ( 28 ) page: 14347 - 14353   2020.5

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    Carbon materials have previously been reported to work as catalysts for hydrogen (H-2) 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 sp(2) bonds. To understand the catalytic behavior of carbon materials for H-2 production by methane (CH4) decomposition, the catalytic behavior of fullerenes with 6-membered rings and also those comprising 5- and 7-membered rings with sp(2) 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.H-2 production started at 400 degrees C and the H-2 production rate gradually increased with time, and the activation energy of the fullerene for H-2 production by CH4 decomposition was found to be 166 kJ/mol. Moreover, in situ heating X-ray photon spectroscopy (XPS) measurements showed that the pi-pi* transition signal becomes stronger with increasing temperature above the threshold of 300 degrees C. The transition of the pi. electrons to pi* orbitals upon heating is expected to decompose CH 4 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 degrees 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 sp(2) bonding contribute to this catalytic behavior for CH4 decomposition at a low temperature of 400 degrees C. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

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  45. Blue photo luminescence from 3 mol%Y2O3-doped ZrO2 polycrystals sintered by flash sintering under an alternating current electric field Reviewed

    Yudai Yamashita, Tsuyoshi Kurachi, Tomoharu Tokunaga, Hidehiro Yoshida, Takahisa Yamamoto

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   Vol. 40 ( 5 ) page: 2072 - 2076   2020.5

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    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 degrees 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.

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  46. Suppression of nitridation of yttria-doped zirconia during flash sintering Reviewed International coauthorship

    Tsuyoshi Kurachi, Yudai Yamashita, Tomoharu Tokunaga, Hidehiro Yoshida, Takahisa Yamamoto

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   Vol. 103 ( 5 ) page: 3002 - 3007   2020.5

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    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.

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  47. In situ TEM observation of liquid-state Sn nanoparticles vanishing in a SiO2 structure: a potential synthetic tool for controllable morphology evolution from core-shell to yolk-shell and hollow structures Reviewed International coauthorship

    Shilei Zhu, Mai Thanh Nguyen, Tomoharu Tokunaga, Cheng-Yen Wen, Tetsu Yonezawa

    NANOSCALE ADVANCES   Vol. 2 ( 4 ) page: 1456 - 1464   2020.4

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    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.

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  48. Highly Correlated Size and Composition of Pt/Au Alloy Nanoparticles via Magnetron Sputtering onto Liquid. Reviewed International journal

    Lianlian Deng, Mai Thanh Nguyen, Jingming Shi, Yuen-Ting Rachel Chau, Tomoharu Tokunaga, Masaki Kudo, Syo Matsumura, Naoyuki Hashimoto, Tetsu Yonezawa

    Langmuir : the ACS journal of surfaces and colloids   Vol. 36 ( 12 ) page: 3004 - 3015   2020.3

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    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.

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

    Yuen-ting Rachel Chau, Mai Thanh Nguyen, Mingbei Zhu, Arnaud Romier, Tomoharu Tokunaga, Tetsu Yonezawa

    New Journal of Chemistry   Vol. 44 ( 12 ) page: 4704 - 4712   2020.3

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    <p>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.</p>

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

    Yudai Yamashita, Asa Itoh, Tomoharu Tokunaga, Hidehiro Yoshida, Takahisa Yamamoto

    Applied Physics Express   Vol. 13 ( 3 )   2020.3

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    © 2020 The Japan Society of Applied Physics. 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.

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

    Mai Thanh Nguyen, Kai Yu, Tomoharu Tokunaga, Kornkit Boonyaperm, Soorathep Kheawhom, Masashi Arita, Tetsu Yonezawa

    ACS SUSTAINABLE CHEMISTRY & ENGINEERING   Vol. 7 ( 21 ) page: 17697 - 17705   2019.11

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    This research is devoted for the synthesis of Fe oxide and Fe nanoparticles (NPs) via, respectively, thermal decomposition of iron(III) oleate and H-2 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 H-2 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.

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  52. Technique to control specimen electric current during a flash state with alternating current electric fields Reviewed

    Yudai Yamashita, Tsuyoshi Kurachi, Tomoharu Tokunaga, Hidehiro Yoshida, Takahisa Yamamoto

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 127 ( 11 ) page: 849 - 851   2019.11

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    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 mot% Y2O3-doped ZrO2 compacts prepared by DC- and AC-flash sintering emit blue fluorescence (FL) under 254 nm ultraviolet tight. 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 mot% Y2O3-doped ZrO2 compacts. (C) 2019 The Ceramic Society of Japan. All rights reserved.

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  53. One-minute Joule Annealing Enhances the Thermoelectric Properties of Carbon Nanotube Yarns via the Formation of Graphene at the Interface Reviewed

    Masaki Hada, Taisuke Hasegawa, Hirotaka Inoue, Makito Takagi, Kazuki Omoto, Daiki Chujo, Shogo Iemoto, Taihei Kuroda, Taiga Morimoto, Takuma Hayashi, Toru Iijima, Tomoharu Tokunaga, Naoshi Ikeda, Kazuhiro Fujimori, Chihiro Itoh, Takeshi Nishikawa, Yoshifumi Yamashita, Toshihiko Kiwa, Shin-ya Koshihara, Satoshi Maeda, Yasuhiko Hayashi

    ACS Appl. Energy Mater.   Vol. 2 ( 10 ) page: 7700 - 7708   2019.10

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    DOI: 10.1021/acsaem.9b01736

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  54. Selective Reduction Mechanism of Graphene Oxide Driven by the Photon Mode versus the Thermal Mode. Reviewed International journal

    Masaki Hada, Kiyoshi Miyata, Satoshi Ohmura, Yusuke Arashida, Kohei Ichiyanagi, Ikufumi Katayama, Takayuki Suzuki, Wang Chen, Shota Mizote, Takayoshi Sawa, Takayoshi Yokoya, Toshio Seki, Jiro Matsuo, Tomoharu Tokunaga, Chihiro Itoh, Kenji Tsuruta, Ryo Fukaya, Shunsuke Nozawa, Shin-Ichi Adachi, Jun Takeda, Ken Onda, Shin-Ya Koshihara, Yasuhiko Hayashi, Yuta Nishina

    ACS nano   Vol. 13 ( 9 ) page: 10103 - 10112   2019.9

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    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.

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  55. Porous ZnV2O4 Nanowire for Stable and High-Rate Lithium-Ion Battery Anodes Reviewed

    Lyn Marie, Z. De Juan-Corpuz, Mai Thanh Nguyen, Ryan D. Corpuz, Tetsu Yonezawa, Nataly Carolina Rosero-Navarro, Kiyoharu Tadanaga, Tomoharu Tokunaga, Soorathep Kheawhom

    ACS Applied Nano Materials   Vol. 2 ( 7 ) page: 4247 - 4256   2019.7

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    DOI: 10.1021/acsanm.9b00703

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  56. Preparation and Growth Mechanism of Pt/Cu Alloy Nanoparticles by Sputter Deposition onto a Liquid Polymer. Reviewed International journal

    Lianlian Deng, Mai Thanh Nguyen, Shuang Mei, Tomoharu Tokunaga, Masaki Kudo, Syo Matsumura, Tetsu Yonezawa

    Langmuir : the ACS journal of surfaces and colloids   Vol. 35 ( 25 ) page: 8418 - 8427   2019.6

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    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.

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

    Shilei Zhu, Mai Thanh Nguyen, Tomoharu Tokunaga, Tetsu Yonezawa

    ACS APPLIED NANO MATERIALS   Vol. 2 ( 6 ) page: 3752 - 3760   2019.6

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    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 degrees C.

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  58. Topologically immobilized catalysis centre for long-term stable carbon dioxide reforming of methane Reviewed International journal

    Shusaku Shoji, Xiaobo Peng, Tsubasa Imai, Paskalis Sahaya Murphin Kumar, Kimitaka Higuchi, Yuta Yamamoto, Tomoharu Tokunaga, Shigeo Arai, Shigenori Ueda, Ayako Hashimoto, Noritatsu Tsubaki, Masahiro Miyauchi, Takeshi Fujita, Hideki Abe

    CHEMICAL SCIENCE   Vol. 10 ( 13 ) page: 3701 - 3705   2019.4

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    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.

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  59. Nanoporous Nickel Composite Catalyst for the Dry Reforming of Methane. Reviewed International journal

    Takeshi Fujita, Xiaobo Peng, Akira Yamaguchi, Yohei Cho, Yongzheng Zhang, Kimitaka Higuchi, Yuta Yamamoto, Tomoharu Tokunaga, Shigeo Arai, Masahiro Miyauchi, Hideki Abe

    ACS omega   Vol. 3 ( 12 ) page: 16651 - 16657   2018.12

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    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.

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  60. Intergranular amorphous films formed by DC electric field in pure zirconia Reviewed

    Nobuhiro Morisaki, Hidehiro Yoshida, Tetsuro Kobayashi, Tomoharu Tokunaga, Takahisa Yamamoto

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   Vol. 101 ( 8 ) page: 3282 - 3287   2018.8

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    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 degrees C, which is lower than the sintering temperature. In contrast, pure monoclinic ZrO2 can be consolidated without shattering using flash-sintering at 1350 degrees C for 5minutes under an applied DC electric field of 175V/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 degrees C for 5minutes. 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.

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

    David Čempel, Mai Thanh Nguyen, Yohei Ishida, Tomoharu Tokunaga, Tetsu Yonezawa

    New Journal of Chemistry   Vol. 42 ( 8 ) page: 5681 - U9   2018.4

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    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.

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  62. Sputter Deposition toward Short Cationic Thiolated Fluorescent Gold Nanoclusters: Investigation of Their Unique Structural and Photophysical Characteristics Using High-Performance Liquid Chromatography Reviewed International journal

    Yohei Ishida, Akihiro Morita, Tomoharu Tokunaga, Tetsu Yonezawa

    LANGMUIR   Vol. 34 ( 13 ) page: 4024 - 4030   2018.4

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    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

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  63. Au/Cu Bimetallic Nanoparticles via Double-Target Sputtering onto a Liquid Polymer Reviewed International journal

    Mai Thanh Nguyen, Hong Zhang, Lianlian Deng, Tomoharu Tokunaga, Tetsu Yonezawa

    LANGMUIR   Vol. 33 ( 43 ) page: 12389 - 12397   2017.10

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    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.

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

    Takeshi Fujita, Kimitaka Higuchi, Yuta Yamamoto, Tomoharu Tokunaga, Shigeo Arai, Hideki Abe

    METALS   Vol. 7 ( 10 ) page: 406   2017.10

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    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.

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  65. Consolidation of undoped, monoclinic zirconia polycrystals by flash sintering Reviewed

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

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   Vol. 100 ( 9 ) page: 3851 - 3857   2017.9

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    Consolidated, monoclinic ZrO2 polycrystal was produced from undoped ZrO2 powders in air by flash sintering at the sintering temperature of 1350 degrees C for 5minutes or 3hours under an applied DC electric field of 175V/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 degrees C below the sintering temperature of 1350 degrees C. When the furnace temperature was decreased from the sintering temperature of 1350 degrees C to room temperature, volumetric expansion associated with tetragonal-to-monoclinic phase transformation gradually took place at the furnace temperature from 1000 degrees C to 750 degrees 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 degrees C, and shattered. SEM observation revealed the presence of grain-boundary second phase in the flash-sintered specimen for 3hours, 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 5minutes, 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 3hours while the grain alignment could not be observed in flash-sintered specimen for 5minutes. 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.

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  66. Electric current-controlled synthesis of BaTiO3 Reviewed

    Yu Nakagawa, Hidehiro Yoshida, Akinori Uehashi, Tomoharu Tokunaga, Katsuhiro Sasaki, Takahisa Yamamoto

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   Vol. 100 ( 9 ) page: 3843 - 3850   2017.9

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    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 degrees 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.

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

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

    CRYSTAL GROWTH & DESIGN   Vol. 17 ( 9 ) page: 4554 - 4562   2017.9

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    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.

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  68. Small Nanosized Oxygen-Deficient Tungsten Oxide Particles: Mechanistic Investigation with Controlled Plasma Generation in Water for Their Preparation Reviewed International journal

    Yohei Ishida, Shingo Motono, Wataru Doshin, Tomoharu Tokunaga, Hiroki Tsukamoto, Tetsu Yonezawa

    ACS OMEGA   Vol. 2 ( 8 ) page: 5104 - 5110   2017.8

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    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.

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  69. 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, Hirotaka Inoue, Gehan A. J. Amaratunga

    CARBON   Vol. 120   page: 358 - 365   2017.8

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    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. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.carbon.2017.05.034

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  70. Nanophase-separated Ni3Nb as an automobile exhaust catalyst International journal

    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   Vol. 8 ( 5 ) page: 3374 - 3378   2017.5

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    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 N-2 generation, and the NbOx matrix absorbs excessive nitrogen adatoms to retain the active Ni-0 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.

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  71. 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

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 125 ( 4 ) page: 185 - 189   2017.4

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    Recently, carbon materials were reported to work as catalysts for the production of H-2 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 H-2 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 H-2 production by carbon materials should be discussed. Herein, the H-2 production rate was measured under conditions employing a low flow rate of CH4 and a large quantity of carbon black (CB) as a catalyst. H-2 production started at 600 degrees 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 H-2 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. (C) 2017 The Ceramic Society of Japan. All rights reserved.

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

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

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   Vol. 90 ( 3 ) page: 279 - 285   2017.3

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    Au/Pd alloy nanoparticles (NPs) were successfully synthesized using HAuCl4, H2PdCl4, and alpha-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.

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

    Yoshimitsu Hayashi, Tomoharu Tokunaga, Katsuhiro Sasaki, Takahisa Yamamoto

    INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS   Vol. 62   page: 9 - 13   2017.1

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    WC grains in WC-Co alloys are shaped as truncated triangular prisms, each with a basal plane of a (0001) truncated triangle and two {1 (1) over bar 00} 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 &lt;0001&gt; projection. We directly determined the relationship between the two {1 (1) over bar 00} 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-C bonds formed. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijrmhm.2016.10.013

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  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   Vol. 120   page: 358–365   2017

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  75. Nanophase-separated Ni3Nb as Automobile Exhaust Catalysts Reviewed

    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   Vol. 8   page: 3374-3378   2017

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

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

    Bulletin of the Chemical Society of Japan   Vol. 90 ( 3 ) page: 279-285   2017

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  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   Vol. 125 ( 4 ) page: 185-189   2017

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  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)     page: 357-361   2017

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

    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)     page: 357 - 361   2017

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    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.

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  80. Double target sputtering into liquid Reviewed

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

    Materials Letters   Vol. 171 ( 15 ) page: 75-78   2016

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  81. Earth-Abundant and Durable Nanoporous Catalyst for Exhaust-Gas Conversion Reviewed

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

    Advanced Functional Materials     page: 1-8   2016

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  82. Hard-Templating Synthesis of Macroporous Platinum Microballs Reviewed

    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   Vol. 164 ( 1 ) page: 488-492   2016

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  83. Synthesis of zirconium oxynitride in air under DC electric fields Reviewed

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

    Applied Physics Letter   Vol. 109   page: 083104(1)- 083104(4)   2016

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

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

    Journal of the Ceramic Society of Japan   Vol. 124 ( 4 ) page: 388-392   2016

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

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

    Langmuir   Vol. 32   page: 12159-12165   2016

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

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

    Langmuir   Vol. 32   page: 12159-12165   2016

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  87. Hard-Templating Synthesis of Macroporous Platinum Microballs (MPtM) Reviewed

    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   Vol. 164 ( 1 ) page: 488-492   2015

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  88. Enhancement of sintering rates in BaTiO3 by controlling of DC electric current Reviewed

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

      Vol. 123 ( 6 ) page: 465-468   2015

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  89. In-situ observation of carbon nanotube yarn during voltage application Reviewed

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

    Micron   Vol. 74   page: 30-34   2015

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  90. Environment-Sensitive Thermal Coarsening of Nanoporous Gold Reviewed

    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   Vol. 56 ( 4 ) page: 468-472   2015

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

      Vol. 17 ( 38 ) page: 24556-24559   2015

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  92. Mechanism for the Precipitation of Carbon on the surface of an Ni Catalyst Reviewed

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

    AMTC Letters   Vol. 4   page: 60-61   2014

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  93. Domain Structure of LSAT Single Crystal Reviewed

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

    AMTC Letters   Vol. 4   page: 34-35   2014

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  94. Yttrium Segregation Behavior to Necks during Sintering in Aluminum Doped with Yttria Reviewed

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

    AMTC Letters   Vol. 4   page: 36-37   2014

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  95. Atomic Observation of Catalysis-Induced Nanopore Coarsening of Nanoporous Gold Reviewed

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

    Nano Letters   Vol. 14 ( 3 ) page: 1172-1177   2014

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  96. In Situ TEM Observation of Double-Wall TiO2 Nanotube Reviewed

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

    Chemistry Letters   Vol. 43 ( 9 ) page: 1514-1516   2014

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

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

    Nanoscale Research Letters   Vol. 8   page: 302(1)-302(7)   2013

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  98. Microstructural analysis of thermal degradation of palladium-coated niobium membrane Reviewed

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

      Vol. 573   page: 192-197   2013

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

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

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

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

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

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

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

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

    ECS Transactions   Vol. 57 ( 1 ) page: 1455-1462   2013

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  102. Growth and structure analysis of tungsten oxide nanorods using environmental TEM Reviewed

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

    Nanoscale Research Letters   Vol. 7   page: 85(1-7)   2012.1

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  103. Temperature distributions of electron beam-irradiated samples by scanning electron microscopy Reviewed

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

    Journal of Microscopy     page: in-press   2012

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

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

    Nanoscale Research Letters     page: inpress   2012

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  105. Atomic origins of the high catalytic activity of nanoporous gold Reviewed

    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   Vol. 11   page: 775-780   2012

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

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

    AMTC Letters   Vol. 3   page: 88-89   2012

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  107. A method for Accurate Temperature Measurement Using Infrared Thermal Camera Reviewed

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

    Journal of Electron Microscopy   Vol. 0   page: 1-5   2012

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

    Takashi Narushima, Makino T, Tomoharu Tokunaga,Tetsu Yonezawa

    Journal of Nanoscience and Nanotechnology   Vol. 12 ( 3 ) page: 2612-2616   2012

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  109. Fabrication of Ge nanoneedles by ion-irradiation method Reviewed

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

    Surf. and Coat. Tech.     page: inpress   2011.6

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  110. Direct Growth of Horizontally Alligned Carbon Nanotubes between Electrodes and Its Application to Field-Effect Transistors Invited Reviewed

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

    J. Nanosci. Nanotechnol     page: inpress   2011.6

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

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

    Proceedings of IEEE INEC 2011     page: 102   2011.5

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  112. Growth and structure analysis of tungsten oxide nanorods using environmental TEM Reviewed

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

    Proceedings of IEEE INEC 2011     page: 62   2011.5

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  113. *In-situ TEM observation of internal metal inside metal filled carbon fiber Reviewed

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

    Diamond and Related Materials   Vol. 20 ( 2 ) page: 210-212   2011.3

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  114. TEM observation of structure and growth of the tungsten oxide nanorods Reviewed

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

    AMTC Letters   Vol. 2   page: 80-81   2010.6

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

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

    AMTC Letters   Vol. 2   page: 92-93   2010.6

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  116. TEM characterization of sintered copper nanoparticles covered by biopolymer nanoskin Reviewed

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

    AMTC Letters   Vol. 2   page: 88-89   2010.6

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

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

    Diamond and Related Materials   Vol. 18 ( 2-3 ) page: 341-344   2009

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  118. TEMその場観察に用いる加熱体の問題点と検討 Invited

    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     page: 47-52   2009

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    Authorship:Lead author   Language:Japanese  

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

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

    IEICE TRANS. ELECTRON.   Vol. E92-C ( 12 ) page: 1417-1420   2009

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  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

      Vol. 1   page: 258-259   2008.6

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

    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   Vol. 17 ( 7-10 ) page: 1525-1528   2008

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  122. Low-Temperature fabrication of Ge nanostructures by ion irradiation Reviewed

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

    Trans. Mater. Soci. Jpn   Vol. 33   page: 1015-1018   2008

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  123. Microstructure and mechanical properties of aluminum fullerene composite fabricated by high pressuretorsion Reviewed

    Tomoharu Tokunaga, Kenji Kaneko, Keisuke Sato, Zenji Horita

    Scripta Materialia   Vol. 58 ( 9 ) page: 735-738   2008

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  124. *Production of aluminum-matrix carbon nanotube composite using high pressure torsion Reviewed

    Tomoharu Tokunaga, Kenji Kaneko, Zenji Horita

    Materials Science and Engineering: A   Vol. 490 ( 1-2 ) page: 300-304   2008

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

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

    Applied Physics Letter   Vol. 90   page: 133116   2007

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

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

    Scripta Materiallia   Vol. 57 ( 3 ) page: 281-284   2007

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

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

    Japanese Journal of Applied Physics   Vol. 45 ( 32 ) page: L860–L863   2006

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

    Takeshi Fujita, Yasuhiko Hayashi, Tomoharu Tokunaga, Kazuhisa Yamamoto

    Applied Physics Letter   Vol. 84   page: 243118   2006

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  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     page: 66   2006

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  130. Effect of Thermal Annealing and Oxidative Purification on Multi Wall Carbon Nanotube Reviewed

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

    Proceedings of The 16th International Microscopy Congress     page: 158   2006

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  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     page: 297   2006

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

    Yasuhiko Hayashi, Tomoharu Tokunaga, Kenji Kaneko, Zenji Horita

    Diamond and Related Materials   Vol. 15   page: 1138-1142   2006

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

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

    Scripta Materiallia   Vol. 52   page: 1205-1209   2005

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  134. Ion Implantation Effects of Microcrystalline and Nanocrystalline Diamond Thin Films Reviewed

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

    Japanese Journal of Applied Physics   Vol. 43 ( 12 ) page: 7971-7975   2004

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

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

    Applied Physics Letters   Vol. 84   page: 2886-2888   2004

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

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

    Diamond and Related Materials   Vol. 13 ( 4-8 ) page: 1198-1202   2004

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  137. Microstructure of metal-filled carbon nanotubes Reviewed

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

    Journal of Electron Microscopy   Vol. 53 ( 2 ) page: 149-155   2004

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▼display all

Books 4

  1. まてりあ Reviewed

    徳永智春( Role: Sole author ,  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  2021.6 

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    Total pages:8   Responsible for pages:351-358   Language:Japanese Book type:Textbook, survey, introduction

    DOI: doi:10.2320/materia.60.351

  2. まてりあ Reviewed

    徳永智春( Role: Sole author ,  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  2021.3 

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    Total pages:9   Responsible for pages:225-233   Language:Japanese Book type:Textbook, survey, introduction

  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( Role: Sole author ,  第三章第二節)

    R&D出版  2020.12 

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    Total pages:354   Responsible for pages:137-148   Language:Japanese Book type:Textbook, survey, introduction

  4. Modern Technology and Applications of Metal Nano- and Microparticles

    ( Role: Joint author)

    2013.11  ( ISBN:978-4-7813-0827-2

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    Language:Japanese

MISC 1

  1. B-site ordered atomic structure in LSAT: (La0.3Sr0.7)(Al0.65Ta0.35)O3 single crystal Reviewed

    Shunsuke Kobayashi

      Vol. 58 ( 2 ) page: 93 - 93   2019.2

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    Language:Japanese  

    DOI: 10.2320/materia.58.93

Presentations 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 Invited

    徳永智春

    その場観察分科会 2021年研究討論会  2021.10.22  日本顕微鏡学会

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    Event date: 2021.10

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:オンライン   Country:Japan  

  2. Photoluminescence property control of Ga2O3 by flash sintering International conference

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

    The XVIIIth Conference of the European Ceramic Society  2023.7.6 

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    Event date: 2023.7

    Language:English   Presentation type:Oral presentation (general)  

  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 Invited

    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  2023.6.6 

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    Event date: 2023.6

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  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 Invited

    徳永智春

    ナノ学会第21回大会  2023.5.12 

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    Event date: 2023.5

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  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 Invited

    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  2022.12.10  応用物理学会 名古屋大学SC 事務局

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    Event date: 2022.12

    Language:Japanese  

    Venue: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  2021.5.13  日本顕微鏡学会

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    Event date: 2021.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:オンライン   Country:Japan  

  7. STEM-EELS Analysis of ALD-AlOx Thin Film which is Non-uniform Composition

    2020.11 

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    Event date: 2020.11

    Language:Japanese   Presentation type:Poster presentation  

  8. Ion generated inside gas environment TEM and possibility of active elements generation

    2020.11 

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    Event date: 2020.11

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  9. Analysis of Ion Environment Generated inside Gas Environmental TEM and Nitriding Reaction of Metal by Nitrogen Ion

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    Event date: 2020.6

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 Invited

    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~ 

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    Event date: 2016.12

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:愛知,分子科学研究所 明大寺キャンパス   Country:Japan  

  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 

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    Event date: 2016.9

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 Invited International conference

    徳永智春

    SPring-8 Seminar(第253回) 

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    Event date: 2016.8

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  13. TEMやSTEMを使ってみよう。 Invited

    徳永智春

    北海道大学材料科学専攻 マテリアルセミナー 

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    Event date: 2015.1

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 

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    Event date: 2014.2

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:北海道大学   Country:Japan  

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

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

    SOFC 13 

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    Event date: 2013.10

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  16. Fabrication of Metal Nanoparticle from Metal Filled Carbon Nanofibers and Their Size Control by Heating International conference

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

    IEEE NMDC 2013 

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    Event date: 2013.10

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

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

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

    IEEE NMDC 2013 

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    Event date: 2013.10

    Language:English   Presentation type:Oral presentation (general)  

    Country:Taiwan, Province of China  

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

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

    International Conference on Diamond and Carbon Materials 2012 

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    Event date: 2012.9

    Language:English   Presentation type:Oral presentation (general)  

    Country:Spain  

  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 

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    Event date: 2012.3

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  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」 

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    Event date: 2012.1

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Country:Japan  

  21. Development of in-situ observation technology for evaluation of SOFC anode Materials by environmental transmission electron microscope International conference

    MRS Fall Meeting & Exhibit 

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    Event date: 2011.11

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2011.6 - 2011.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2011.6 - 2011.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  24. The Growth and Characterization of Zn Nanowires Covered with ZnO using Plasma-assisted Molecular Beam Irradiation International conference

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

    IEEE International Nano Electronic Conference 

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    Event date: 2011.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  25. Growth and Structure Analysis of Tungsten Oxide Nanorods using Environmental Transmission Electron Microscopy International conference

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

    IEEE International Nano Electronic Conference 

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    Event date: 2011.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 International conference

    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 

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    Event date: 2011.5

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 

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    Event date: 2011.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  28. The Investigation for Growth Mechanism of Tungsten Oxide Nanorods Using Environmental TEM International conference

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

    The 4th International Workshop on Advanced Ceramics 

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    Event date: 2010.12

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  29. Growth and Structure Analysis of Tungsten Oxide Nanorods using Environmental TEM International conference

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

    8th International Vacuum Electron Sources Conference and Nanocarbon 

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    Event date: 2010.10

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2010.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 

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    Event date: 2010.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2010.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2010.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2010.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  35. In-situ TEM observation of internal metal inside metal filled carbon fiber International conference

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

    4th International Conference on New Diamond and Nano Carbons 

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    Event date: 2010.5

    Language:English   Presentation type:Poster presentation  

    Country:China  

  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 

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    Event date: 2009.11

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Country:Japan  

  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 

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    Event date: 2009.7

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Country:Japan  

  38. Growth of the tungsten oxide nanorods: an in-situ TEM observation study International conference

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

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    Event date: 2009

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2009

    Language:Japanese  

    Country:Japan  

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

    The 2nd International Symposium on Functional Innovation of Molecular Informatics 

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    Event date: 2006.10

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2006.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  42. Effect of Thermal Annealing and Oxidative Purification on Multi Wall Carbon Nanotube International conference

    The 16th International Microscopy Congress 

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    Event date: 2006.9

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

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

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    Event date: 2006.7

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  44. Aluminum and Carbon Nanotube Composites Fabricated Using High Pressure Torsion Process International conference

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    Event date: 2006.6

    Language:English  

  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 

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    Event date: 2006.6

    Language:Japanese   Presentation type:Oral presentation (general)  

  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

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    Event date: 2005.12

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 

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    Event date: 2005.11

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 

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    Event date: 2005.11

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  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 

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    Event date: 2004.7

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  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 

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    Event date: 2004.1

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

    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 

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    Event date: 2003.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

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Research Project for Joint Research, Competitive Funding, etc. 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

    2009.4 - 2010.3

    企業からの受託研究 

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    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

    2008.4 - 2010.3

    中部経済産業局 

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    Grant type:Competitive

  3. カーボンナノチューブを用いた電子放出特性の研究

    2008.4 - 2009.3

    企業からの受託研究 

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    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

    2005.4 - 2007.3

    中部経済産業局 

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    Grant type:Competitive

    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。

KAKENHI (Grants-in-Aid for Scientific Research) 9

  1. 常温焼成可能な銅ナノ粒子導電材料の実現

    Grant number:23K17855  2023.6 - 2025.3

    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

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    Authorship:Coinvestigator(s) 

    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. Preparation of rapid conductive thin film layer by nano-copper blow-out by slightly oxidized copper particles and low temperature sintering

    Grant number:19K22094  2019.6 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Research (Exploratory)

    Yonezawa Tetsu

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    In this study, we synthesized slightly oxidized (CuxO, x>8) copper nanoparticles, copper nanoparticles with slightly oxidized phase on the surface layer and their mixtures as low temperature sintering materials. We succeeded in establishing an industrial synthesis method to obtain more than several tens of grams/batch. The obtained fine particles were dispersed in dipropylene glycol using a bead mill or a film swirling milling method. By determining the optimized milling conditions, we were able to synthesize a stable paste. At present, it was found that the copper particulate content could be as high as 80 wt% or more. When this paste was applied to a substrate and sintered at less than 200 degree C, we succeeded in forming a conductive film with a low resistivity within a few times that of the bulk. They also showed that the film formation mechanism is due to "nano-copper blowout," which is an enhanced diffusion of atoms.

  3. Optimization of nanoparticles for development of ultra-broadband light sources

    Grant number:18KK0159  2018.10 - 2022.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))

    Tetsu Yonezawa

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    Authorship:Coinvestigator(s)  Grant type:Competitive

    Interaction of intense laser pulses with condensed matter, especially, nanoparticle stable aqueous dispersions, is expected to produce a variety of nonlinear optical effects. Among them, there have been independent experimental studies on high-energy pulsed X-ray (keV) generation through high-temperature plasmas for wavelength conversion and on low-energy terahertz wave (meV) generation based on higher-order nonlinear optical effects. In this study, femtosecond pulsed lasers have been irradiated to various nanoparticle aqueous dispersions and the energy generated from them have been detected. As a result, X-rays were efficiently extracted from Au nanoparticle aqueous dispersions, and THz-wave emission was also obtained from the Cu2O/Cu thin-layer interface. THz emission was also obtained from ZnTe nanoparticle aqueous dispersions, indicating that the interaction of intense laser pulses with condensed systems such as nanoparticles can produce an ultra-broadband light.

  4. Is an in-situ gas environment TEM truly showing the reaction between materials and gases?

    Grant number:18K04824  2018.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Tokunaga Tomoharu

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    Authorship:Principal investigator 

    Grant amount:\4420000 ( Direct Cost: \3400000 、 Indirect Cost:\1020000 )

    It was found that ions and electrons associated with the ionization of gas molecule were generated in the nitrogen gas atmosphere during electron beam (EB) irradiation, and the generated ions were found to be N2+ ions. This result indicates that not only gas but also ions are present in the gas environment during EB irradiation. When Cr2O3 was kept in this atmosphere, it was found to be nitrided. Researchers should consider the effect of ions when observing specimens in a gas atmosphere during EB irradiation.

  5. Development of ultra high strength more than 6GPa ultra light wegiht carbon nanotube spun yarn

    Grant number:18H01708  2018.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    HAYASHI Yasuhiko

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    In this study, carbon nanotube (CNT) yarns were fabricated from tall and high-density, few-walled CNT forest synthesized on the substrate by dry spinning method to achieve CNT yarns with tensile strength exceeding the strength of carbon fibers, which is a benchmark for practical use. The shape and diameter change of the catalytic metal particles from room temperature to the initial temperature of CNT synthesis was clarified, which enabled the selective synthesis of double-layer CNTs. We also found that the removal of residual amorphous carbon and the structural change to graphene occurred simultaneously when the entire CNT yarn was heated by joule heating in vacuum and extreme ethane gas. Furthermore, by using a spinning technique to orient the CNTs in one direction, a high strength of over 2.5 GPa was achieved.

  6. Preparation of Stable and Efficient Fluorescent Alloy Nanoparticles by Matrix Sputtering

    Grant number:18H01820  2018.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    Yonezawa Tetsu

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    In this study, nanoparticle synthesis, especially alloy nanoparticles, was carried out by matrix sputtering method using a multidimensional magnetron sputtering system. The obtained particles were stable and well dispersed. Direct sputtering onto TEM grids was also performed. The obtained microstructures were investigated in detail using XRD and aberration-corrected (atom-resolved) STEM, and the optical properties were investigated.
    Crystal structure analysis by XRD and atomic arrangement analysis by STEM revealed that each of the obtained nanoparticles is an alloy and has a solid solution structure. This was a characteristic of the matrix sputtering method. The optical properties were also investigated and showed luminescence.

  7. Grain boundary structure of ceramics

    Grant number:26249088  2014.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)  Grant-in-Aid for Scientific Research (A)

    Yamamoto Takahisa, MUTO Shunsuke

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    Unique coordination polyhedral are formed at grain boundaries, which are different from those in grain interiors. These unique coordination polyhedral often affect physical properties of polycrtals. In this study, we investigated that the relationship between the grain boundary structures and phenomena due to the unique coordination polyhedras. For example, applied electric fields greatly enhance the shrinkage rate of ceramic green compacts. The electric fields tend to concentrate at grain boundaries. The concentration of the fileds were found to reduce at/near grain boundaries by using HR-TEM/STEM, EELS and so on. In order to use the reducing phenomena, we could successfully nitrize oxide ceramic in air. In addition, the reducing effects were revealed to depend on the grain orientation relationship.

  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

    2010.4 - 2013.3

    科学研究費補助金  若手研究(B)

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    Authorship:Principal investigator 

  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

    2008.9 - 2010.3

    科学研究費補助金  若手スタートアップ 20860041

    徳永智春

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Industrial property rights 5

  1. 水素製造方法及び水素製造装置

    徳永 智春,影山 健友

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    Applicant:徳永 智春,影山 健友

    Application no:特願2016-172936  Date applied:2016.9

    Country of applicant:Domestic  

  2. カーボンナノチューブ複合体及びその製造方法

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    Application no:特許出願2006-331078  Date applied:2006.12

    Announcement no:特許公開2008-144207 

    Country of applicant:Domestic  

  3. フラーレン複合体及びその製造方法

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    Application no:特許出願2006-331228  Date applied:2006.12

    Announcement no:特許公開2008-144208 

    Country of applicant:Domestic  

  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

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    Applicant:林 靖彦, 徳永智春, 藤田武志

    Application no:107470  Date applied:2006

    Patent/Registration no:4892723  Date registered:2012 

    Country of applicant:Domestic  

  5. 金属内包カーボンナノチューブの製造方法

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    Application no:特許出願2003-344405  Date applied:2003.10

    Announcement no:特許公開2005-104814 

    Country of applicant:Domestic  

 

Teaching Experience (On-campus) 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

Teaching Experience (Off-campus) 6

  1. Hokkaido Summer Institute

    2022.10 Hokkaido University)

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    Level:Graduate (liberal arts)  Country:Japan

  2. 先端材料

    2022.4 - 2022.7 Aichi Institute of Technology)

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    Level:Undergraduate (specialized)  Country:Japan

  3. Hokkaido Summer Institute

    2021.8 Hokkaido University)

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    Level:Postgraduate  Country:Japan

  4. 先端材料

    2021.4 - 2021.7 Aichi Institute of Technology)

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    Level:Undergraduate (specialized)  Country:Japan

  5. Hokkaido Summer Institute

    2020.8 - 2020.9 Hokkaido University)

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    Level:Other  Country:Japan

  6. 先端材料

    2020.4 - 2020.7 Aichi Institute of Technology)

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    Level:Undergraduate (specialized)  Country:Japan

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Academic Activities 1

  1. 東海若手セラミスト懇話会

    Role(s):Planning, management, etc.

    セラミクス協会東海支部  2009

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    Type:Academic society, research group, etc.