遠堂 敬史 (エンドウ タカシ)

創成研究機構 ナノテクノロジー連携研究推進室特任助教
Last Updated :2024/12/06

■研究者基本情報

学位

  • 博士(理学), 北海道大学

Researchmap個人ページ

研究者番号

  • 70972305

■経歴

経歴

  • 2022年08月 - 現在
    北海道大学, 創成研究機構, 特任助教
  • 2023年01月
    北海道大学, 電子科学研究所, 特任助教(兼任)
  • 2021年04月 - 2022年07月
    北海道大学, 大学院工学研究院, 技術専門職員
  • 2012年04月 - 2021年03月
    北海道大学, 大学院工学研究院, 技術職員

学歴

  • 2013年03月 - 2018年12月, 北海道大学, 大学院総合化学院, 総合化学専攻 (博士・長期履修生)
  • 2009年04月 - 2011年03月, 北海道大学, 大学院理学院, 化学専攻(修士)
  • 2005年04月 - 2009年03月, 北海道大学, 理学部, 化学科 (学士)

■研究活動情報

受賞

  • 2021年02月, 北海道大学, 教育研究支援業務 総長表彰 奨励賞               
  • 2020年01月, 文部科学省 ナノテクノロジープラットフォーム, 令和元年度技術スタッフ表彰 若手技術奨励賞               
  • 2009年07月, 日本化学会北海道支部, 2009年夏季研究発表会 優秀講演賞               

論文

  • Growth of α-Al2O3 layer involving abnormal oxides in FeCrAl alloy tube fabricated by WEDM process and electrical insulating performance in fusion reactor blanket
    Ryuhei Muto, Masatoshi Kondo, Takashi Endo, Ryunosuke Nishio, Teruya Tanaka
    Surface and Coatings Technology, 493, 131250, 131250, Elsevier BV, 2024年10月
    研究論文(学術雑誌)
  • Reliable Operation in High‐Mobility Indium Oxide Thin Film Transistors
    Prashant R. Ghediya, Yusaku Magari, Hikaru Sadahira, Takashi Endo, Mamoru Furuta, Yuqiao Zhang, Yasutaka Matsuo, Hiromichi Ohta
    Small Methods, Wiley, 2024年08月03日
    研究論文(学術雑誌), Abstract

    Transparent oxide semiconductors (TOSs) based thin‐film transistors (TFTs) that exhibit higher field effect mobility (µFE) are highly required toward the realization of next‐generation displays. Among numerous types of TOS‐TFTs, In2O3‐based TFTs are the front‐running candidate because they exhibit the highest µFE ≈100 cm2 V−1 s−1. However, the device operation of In2O3 TFTs is unreliable; a large voltage shift occurs especially when negative gate bias is applied due to adsorption/desorption of gas molecules. Although passivation of the TFTs is used to overcome such instability, previously proposed passivation materials do not improve the reliability. Here, it is shown that the In2O3 TFTs passivated with Y2O3 and Er2O3 films are highly reliable and do not show threshold voltage shifts when applying gate bias. Positive and negative gate bias is applied to the In2O3 TFTs passivated with various insulating oxides and found that only the In2O3 TFTs passivated with Y2O3 and Er2O3 films do not exhibit threshold voltage shifts. It is observed that only the Y2O3 grew heteroepitaxially on the In2O3 crystal. This is the origin of the high reliability of the In2O3 TFTs passivated with Y2O3 and Er2O3 films. This finding accelerates the development of next‐generation displays using high‐mobility In2O3 TFTs.
  • Solid‐State Electrochemical Thermal Switches with Large Thermal Conductivity Switching Widths
    Zhiping Bian, Mitsuki Yoshimura, Ahrong Jeong, Haobo Li, Takashi Endo, Yasutaka Matsuo, Yusaku Magari, Hidekazu Tanaka, Hiromichi Ohta
    Advanced Science, Wiley, 2024年06月25日
    研究論文(学術雑誌), Abstract

    Thermal switches that switch the thermal conductivity (κ) of the active layers are attracting increasing attention as thermal management devices. For electrochemical thermal switches, several transition metal oxides (TMOs) are proposed as active layers. After electrochemical redox treatment, the crystal structure of the TMO is modulated, which results in the κ switching. However, the κ switching width is still small (<4 W m−1 K−1). In this study, it demonstrates that LaNiOx‐based solid‐state electrochemical thermal switches have a κ switching width of 4.3 W m−1 K−1. Fully oxidized LaNiO3 (on state) has a κ of 6.0 W m−1 K−1 due to the large contribution of electron thermal conductivity (κele, 3.1 W m−1 K−1). In contrast, reduced LaNiO2.72 (off state) has a κ of 1.7 W m−1 K−1 because the phonons are scattered by the oxygen vacancies. The LaNiOx‐based electrochemical thermal switch is cyclable of κ and the crystalline lattice of LaNiOx. This electrochemical thermal switch may be a promising platform for next‐generation devices such as thermal displays.
  • Fabrication and Thermoelectric Properties of Freestanding Ba1/3CoO2 Single-Crystalline Films
    Kungwan Kang, Fumiaki Kato, Akitoshi Nakano, Ichiro Terasaki, Takashi Endo, Yasutaka Matsuo, Hyoungjeen Jeen, Hiromichi Ohta
    ACS Applied Electronic Materials, American Chemical Society (ACS), 2023年10月16日
    研究論文(学術雑誌)
  • Solid-State Electrochemical Thermal Transistors with Strontium Cobaltite–Strontium Ferrite Solid Solutions as the Active Layers
    Zhiping Bian, Qian Yang, Mitsuki Yoshimura, Hai Jun Cho, Joonhyuk Lee, Hyoungjeen Jeen, Takashi Endo, Yasutaka Matsuo, Hiromichi Ohta
    ACS Applied Materials & Interfaces, 15, 19, 23512, 23517, American Chemical Society (ACS), 2023年05月03日, [査読有り]
    英語, 研究論文(学術雑誌)
  • Free-Standing Nanometer-Thick Covalent Organic Framework Films for Separating CO2 and N-2
    Masaki Kato, Ryo Ota, Takashi Endo, Takashi Yanase, Taro Nagahama, Toshihiro Shimada
    ACS APPLIED NANO MATERIALS, 5, 2, 2367, 2374, AMER CHEMICAL SOC, 2022年02月
    英語, 研究論文(学術雑誌), Covalent organic frameworks (COF) have been gathering much attention because the shapes, sizes, and chemical functions of their nanostructured pores can be arbitrarily controlled by designing the organic precursors. We fabricated cm-sized free-standing COF films with the thickness of 50-100 nm by an alternating vacuum deposition polymerization method. Precise adjustment of the stoichiometry by digitally controlled deposition was essential for producing the robust free-standing COF films. High-resolution electron microscopy revealed 3 nm pore structures, which correspond to the atomic structure of the COF. Small angle X-ray diffraction shows the existence of a similar periodicity. The CO2/N-2 gas phase separation properties were evaluated from 10(3)-10(5) Pa, and the parameters for each molecular permeation were determined. Based on the detailed analysis, it was found that the selectivity comes from the greater sorption affinity of CO2 to the COF compared to N-2, which is consistent with the quantum chemical calculation. Since the vapor phase method can be used to coat various shaped templates, our method provides a new option for fabrication of neat COF membranes with various structures and their applications for the separation membrane.
  • Ferroelectric BaTaO2N Crystals Grown in a BaCN2 Flux
    Akira Hosono, Yuji Masubuchi, Shintaro Yasui, Masaki Takesada, Takashi Endo, Mikio Higuchi, Mitsuru Itoh, Shinichi Kikkawa
    INORGANIC CHEMISTRY, 58, 24, 16752, 16760, AMER CHEMICAL SOC, 2019年12月
    英語, 研究論文(学術雑誌), Perovskite-type oxynitride BaTaO2N has been attracting attention for its large dielectric constant, which is almost independent of the temperature by measurements on its ceramics. Its dielectric characteristics are attributed to polar nanoregions (PNRs) in the average cubic crystal structure. Polarization saturation to produce a butterfly-like piezoresponse force microscopy (PFM) signal was observed on BaTaO2N crystals in the present study. Reddish crystallites of BaTaO2N of up to 3.1 mu m in size were grown using a BaCN2 flux. Grain growth proceeded through the formation of a Ruddlesden-Popper-type oxynitride from the reaction between BaTaO2N powder and molten BaCN2. Their electrical property was studied using PFM with special care because of the small size of the crystals. They were found to be much more highly insulating than its ceramics. Ferroelectricity with complete phase inversion was observed on an oxynitride perovskite crystal for the first time. A large coercivity of 50-60 V was observed in the measurement. Such ferroelectricity is ascribed to the PNRs induced by the polar linkages between cis-type TaO4N2 octahedra.
  • Three-dimensional ultrastructure of osteocytes assessed by focused ion beam-scanning electron microscopy (FIB-SEM)
    Tomoka Hasegawa, Tomomaya Yamamoto, Hiromi Hongo, Zixuan Qiu, Miki Abe, Takuma Kanesaki, Kawori Tanaka, Takashi Endo, Paulo Henrique Luiz de Freitas, Minqi Li, Norio Amizuka
    HISTOCHEMISTRY AND CELL BIOLOGY, 149, 4, 423, 432, SPRINGER, 2018年04月
    英語, 研究論文(学術雑誌), The aim of this study is to demonstrate the application of focused ion beam-scanning electron microscopy, FIB-SEM for revealing the three-dimensional features of osteocytic cytoplasmic processes in metaphyseal (immature) and diaphyseal (mature) trabeculae. Tibiae of eight-week-old male mice were fixed with aldehyde solution, and treated with block staining prior to FIB-SEM observation. While two-dimensional backscattered SEM images showed osteocytes' cytoplasmic processes in a fragmented fashion, three-dimensional reconstructions of FIB-SEM images demonstrated that osteocytes in primary metaphyseal trabeculae extended their cytoplasmic processes randomly, thus maintaining contact with neighboring osteocytes and osteoblasts. In contrast, diaphyseal osteocytes extended thin cytoplasmic processes from their cell bodies, which ran perpendicular to the bone surface. In addition, these osteocytes featured thick processes that branched into thinner, transverse cytoplasmic processes; at some point, however, these transverse processes bend at a right angle to run perpendicular to the bone surface. Osteoblasts also possessed thicker cytoplasmic processes that branched off as thinner processes, which then connected with cytoplasmic processes of neighboring osteocytes. Thus, FIB-SEM is a useful technology for visualizing the three-dimensional structures of osteocytes and their cytoplasmic processes.
  • Molten BaCN2 for the sintering and crystal growth of dielectric oxynitride perovskites Sr1-xBaxTaO2N (x=0.04-0.23)
    Akira Hosono, Yuji Masubuchi, Takashi Endo, Shinichi Kikkawa
    DALTON TRANSACTIONS, 46, 48, 16837, 16844, ROYAL SOC CHEMISTRY, 2017年12月
    英語, 研究論文(学術雑誌), Solid phase sintering of dielectric oxynitride perovskites above 1000 degrees C is accompanied by their decomposition. Post-ammonolysis is required to recover their stoichiometric nitrogen content and dielectric properties. In the present work, the oxynitride perovskite SrTaO2N was sintered with a BaCN2 flux at approximately 900 degrees C avoiding its thermal decomposition. The resulting solid product with a relative density of 68.9% showed relative dielectric constants in the range from 68 to 90 with loss values less than 0.11, without the post-ammonolysis. The interior of the solids contained rectangular Sr1-xBaxTaO2N crystals for which 0.04 <= x <= 0.23 reflecting their euhedral form. These crystals were grown in molten BaCN2 from 20 to 100 times larger than the original SrTaO2N particles and had a maximum grain size of 3.7 mu m. The Sr1-xBaxTaO2N precipitated on the surfaces of the residual SrTaO2N crystals that had partially dissolved in the BaCN2 flux. A compositional gradient from barium-rich to strontium-rich was observed in a single crystal of the product on going from the exterior to the interior. This is the first-ever report of the preliminary liquid phase sintering and crystal growth of a dielectric oxynitride perovskite using a molten metal cyanamide.
  • Current mapping of low-energy (120 eV) helium and hydrogen irradiated tungsten by conductive atomic force microscopy
    Hongyu Fan, Takashi Endo, Zhenghua Bi, Weibin Yan, Somei Ohnuki, Qi Yang, Weiyuan Ni, Dongping Liu
    JOURNAL OF NUCLEAR MATERIALS, 486, 191, 196, ELSEVIER SCIENCE BV, 2017年04月
    英語, 研究論文(学術雑誌), Both conductive atomic force microscopy (CAFM) and transmission electron microscopy have been used to characterize the defects or He bubbles in low-energy (120 eV) H and He irradiated tungsten (W). By a comparative study, we find that the current mapping from CAFM is very sensitive in the detection of nanometer-sized defects in low-energy H and He irradiated W. Our calculation confirms that the resistance change in H and He irradiated W is strongly affected by the distance between atomic force microscopy tip and defects/He bubbles. CAFM can accurately detect defects/He bubbles in the W surface layer, however, it is infeasible to measure them in the deep layer (>20 nm), especially due to the existence of defects in the surface layer.(C) 2017 Elsevier B.V. All rights reserved.
  • Magnetic Properties of the Melilite-Type Oxysulfide Sr2MnGe2S6O: Magnetic Interactions Enhanced by Anion Substitution
    Takashi Endo, Yoshihiro Doi, Makoto Wakeshima, Keita Suzuki, Yasutaka Matsuo, Keitaro Tezuka, Takuya Ohtsuki, Yue Jin Shan, Yukio Hinatsu
    INORGANIC CHEMISTRY, 56, 5, 2459, 2466, AMER CHEMICAL SOC, 2017年03月
    英語, 研究論文(学術雑誌), The synthesis, crystal structures, photoluminescence, and magnetic properties of the melilite-type oxysulfide Sr2MnGe2S6O were investigated. This compound crystallizes in the melilite structure with space group P4 ($) over bar2(1)m, in which two kinds of anions, S2- and O2-, occupy different crystallographic sites in an ordered manner. The temperature dependence of the magnetic susceptibility of Sr2MnGe2S6O shows a broad peak due to a two-dimensional magnetic interaction between Mn ions in the ab plane. The specific heat data show that this compound has an antiferromagnetic transition temperature (T-N = 15.5 K) that is much higher than that of the oxide analogue Sr2MnGe2O7 (T-N = 4.4 K). DFT calculations showed that the magnetic interaction is enhanced by covalency in the Mn-s bonding.
  • Biological application of focus ion beam-scanning electron microscopy (FIB-SEM) to the imaging of cartilaginous fibrils and osteoblastic cytoplasmic processes
    Tomoka Hasegawa, Takashi Endo, Erika Tsuchiya, Ai Kudo, Zhao Shen, Yasuhito Moritani, Miki Abe, Tomomaya Yamamoto, Hiromi Hongo, Kanako Tsuboi, Taiji Yoshida, Tomoya Nagai, Naznin Khadiza, Ayako Yokoyama, Paulo Henrique Luiz de Freitas, Minqi Li, Norio Amizuka
    JOURNAL OF ORAL BIOSCIENCES, 59, 1, 55, 62, ELSEVIER SCIENCE BV, 2017年02月
    英語, 研究論文(学術雑誌), Objectives: The aim of this study was the biological application of focused ion beam-scanning electron microscopy (FIB-SEM) to obtain serial sectional images of skeletal tissues that showed the ultrastructure of 1) cartilaginous extracellular fibrils and 2) osteoblastic cytoplasmic processes.Methods: Seven-week-old female wild-type mice were fixed with half-Karnovsky solution and then OsO4, and tibiae were extracted for block staining prior to observation under transmission electron microscope (TEM) and FIB-SEM.Results: TEM showed the fine fibrillar but somewhat amorphous ultrastructure of the intercolumnar septa in the growth plate cartilage. In contrast, FIB-SEM revealed bundles of stout fibrils at regular intervals paralleling the septa's longitudinal axis, as well as vesicular structures embedded in the cartilaginous matrix of the proliferative zone. In the primary trabeculae, both TEM and FIB-SEM showed several osteoblastic cytoplasmic processes on the osteoid, in greater numbers than those seen in the bone matrix. FIB-SEM revealed the agglomeration of cytoplasmic processes beneath osteoblasts that formed a tubular continuum extending from those cells. Based on these findings, we postulated that osteoblasts not only extend their cytoplasmic processes to the bone matrix, but also stack these cell processes on the osteoid of the primary trabeculae.Conclusion: Taken together, these data suggest that FIB-SEM imaging of serial bone sections may facilitate new insights on the ultrastructure of cartilage and bone tissues. (C) 2016 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.
  • Effects of Ni dopant on structural properties of zinc oxide nanorods
    Kyung Ho Kim, Yuya Yoshihara, Yoshio Abe, Midori Kawamura, Takayuki Kiba, Takashi Endo
    MICROELECTRONIC ENGINEERING, 165, 20, 22, ELSEVIER SCIENCE BV, 2016年11月
    英語, 研究論文(学術雑誌), We investigated the effects of Ni dopant on structural properties of zinc oxide (ZnO) nanorods. All rods had a ZnO hexagonal wurtzite structure. Upon incorporation of Ni in ZnO, the length and width of the nanorods decreased and increased, respectively. Furthermore, the Ni-doped ZnO (Ni-ZnO) nanorods exhibited overall superior crystalline quality and orientation without showing lattice distortion, as determined by XRD (X-ray diffraction) and electron backscattering diffraction (EBSD) analyses. Both rod types had a hydrophilic surface, whilst, the only polar surface energy slightly decreased after Ni doping. (C) 2016 Elsevier B.V. All rights reserved.
  • Colorful Carbon Nanopopcorns Formed by Codepositing C-60 with Diamond-like Carbon Followed by Reaction with Water Vapor
    Wei Xie, Aiko Kawahito, Takuya Miura, Takashi Endo, Yongming Wang, Takashi Yanase, Taro Nagahama, Yukitoshi Otani, Toshihiro Shimada
    CHEMISTRY LETTERS, 44, 9, 1205, 1207, CHEMICAL SOC JAPAN, 2015年09月
    英語, 研究論文(学術雑誌), We report the synthesis of a new carbon material diamondlike carbon film codeposited with 1% C-60 molecules by plasma-assisted chemical vapor deposition. The synthesized films exhibited strong iridescent colors after being exposed to an atmosphere containing water vapor. An electron microscopy examination revealed that the film expanded by a factor of more than two, while forming 10-100-nm-sized grain-like structures after its exposure to water vapor. This work demonstrates a new concept of incorporating reaction centers in carbon solids to make carbon-based nanostructures.
  • Fabrication of Fe nanowires on yittrium-stabilized zirconia single crystal substrates by thermal CVD methods
    Kawahito A., Yanase T., Endo T., Nagahama T., Shimada T.
    Journal of applied physics, 117, 17, 17D506, 17D506, American Institute of Physics (AIP), 2015年05月07日
    英語, 研究論文(学術雑誌), Magnetic nanowires (NWs) are promising as material for use in spintronics and as the precursor of permanent magnets because they have unique properties due to their high aspect ratio. The growth of magnetic Fe whiskers was reported in the 1960s, but the diameter was not on a nanoscale level and the growth mechanism was not fully elucidated. In the present paper, we report the almost vertical growth of Fe NWs on a single crystal yttrium-stabilized zirconia (Y0.15Zr0.85O2) by a thermal CVD method. The NWs show a characteristic taper part on the bottom growing from a trigonal pyramidal nucleus. The taper angle and length can be controlled by changing the growth condition in two steps, which will lead to obtaining uniformly distributed thin Fe NWs for applications.
  • Three-dimensional characterization of ODS ferritic steel using by FIB-SEM serial sectioning method
    T. Endo, Y. Sugino, N. Ohono, S. Ukai, N. Miyazaki, Y. Wang, S. Ohnuki
    Microscopy, 63, suppl 1, i23.1, i23, Oxford University Press (OUP), 2014年10月30日
    研究論文(国際会議プロシーディングス)
  • Fe whisker growth revisited: effect of Au catalysis for [021̄] oriented nanowires with 100 nm diameter
    T. Yanase, A. Kawahito, Y. Hashimoto, T. Endo, Y. Wang, T. Nagahama, T. Shimada
    RSC Adv., 4, 52, 27620, 27624, Royal Society of Chemistry (RSC), 2014年
    研究論文(学術雑誌),

    The growth mechanism of Fe nanowires and the role of Au nanoparticle catalysis were revealed using transmission electron microscopy and electron diffraction analysis. Fe nanowire has a high aspect ratio and unique [021̄] orientation.

  • Magnetic and Neutron Diffraction Study on Melilite-Type Oxides Sr2MGe2O7 (M = Mn, Co)
    Takashi Endo, Yoshihiro Doi, Yukio Hinatsu, Kenji Ohoyama
    INORGANIC CHEMISTRY, 51, 6, 3572, 3578, AMER CHEMICAL SOC, 2012年03月
    英語, 研究論文(学術雑誌), The crystal structures and magnetic properties of melilite-type oxides Sr2MGe2O7 (M = Mn, Co) were investigated. These compounds crystallize in the melilite structure with space group P (4) over bar2(1)m, in which the M and Ge ions occupy two kinds of tetrahedral sites in an ordered manner. The magnetic M ions form a square-planar lattice in the ab plane. Both compounds do not show the structural phase transition down to 2.5 K. The temperature dependence of magnetic susceptibility for Sr2MnGe2O7 shows a broad peak at similar to 6.0 K because of a two-dimensional magnetic interaction between Mn ions in the ab plane. At 4.4 K, an antiferromagnetic transition was observed. The magnetic structure was determined by the neutron powder diffraction measurement at 2.5 K. It can be represented by the propagation vector k = (0, 0, 1/2), and the magnetic moments of Mn2+ (3.99 mu(B)) ions order antiferromagnetically in a collinear manner along the c axis. On the other hand, Sr2CoGe2O7 shows an antiferromagnetic transition at 6.5 K with divergence between zero-field-cooled and field-cooled susceptibilities. Its magnetic structure determined at 2.5 K has a magnetic propagation vector k = (0, 0, 0), and the ordered magnetic moment of Co2+ (2.81 mu(B)) adopts a collinear arrangement lying on the ab plane.
  • Orthogonal Spin Arrangement in Quasi-Two-Dimensional La2Co2O3Se2
    Yayoi Fuwa, Takashi Endo, Makoto Wakeshima, Yukio Hinatsu, Kenji Ohoyama
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 132, 51, 18020, 18022, AMER CHEMICAL SOC, 2010年12月
    英語, 研究論文(学術雑誌), The crystal, electronic, and magnetic structures of the cobalt oxyselenide La2Co2O3Se2 were investigated through powder neutron diffraction measurements and band structure calculations. This oxyselenide crystallizes in a tetragonal layered structure with space group 14/mmm. The Co ion is sixfold-coordinated by two oxide ions and four selenide ions, and the face-sharing CoO2Se4 octahedra form Co2OSe2 layers. The band structure calculations revealed that the Co ion is in the divalent high-spin state. Rietveld analysis of the neutron diffraction profiles below 200 K demonstrated that the Co moments have a noncollinear antiferromagnetic structure with the propagation vector k = (1/2, 1/2, 0). The ordered magnetic moment was determined to be 3.5 mu(B) at 10 K, and the directions of the nearest-neighbor Co moments are orthogonal each other in the c plane.
  • Crystal Structures and Magnetic Properties of New Europium Melilites Eu2MSi2O7 (M = Mg, Mn) and Their Strontium Analogues
    Takashi Endo, Yoshihiro Doi, Makoto Wakeshima, Yukio Hinatsu
    INORGANIC CHEMISTRY, 49, 23, 10809, 10814, AMER CHEMICAL SOC, 2010年12月
    英語, 研究論文(学術雑誌), Synthesis, crystal structures, and magnetic properties of melilite-type oxides A(2)MSi(2)O(7) (A = Sr, Eu; M = Mg, Mn) were investigated. These compounds crystallize in the melilite structure with space group P (4) over bar2(1)m. The Eu-151 Mossbauer measurements show that the Eu ions are in the divalent state. The Eu2MgSi2O7 is paramagnetic down to 1.8 K. Long-range antiferromagnetic ordering is observed at 3.4 K for Sr2MnSi2O7. On the other hand, the Eu2MnSi2O7 shows a ferrimagnetic transition at 10.7 K. From the magnetization and specific heat measurements, it is found that the Eu2+ (14 mu(B)) and Mn2+ (5 mu(B)) sublattices order antiferromagnetically. This result indicates that an interaction between f-d electrons (Eu-Mn) predominantly operate in this compound.

その他活動・業績

所属学協会

  • 日本希土類学会               
  • 日本顕微鏡学会               
  • 日本セラミックス協会