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Mikito Ueda
Faculty of Engineering　Materials Science and Engineering　Ecological Materials
Professor
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Last Updated :2024/05/09

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Affiliation

  • Faculty of Engineering　Materials Science and Engineering　Ecological Materials

Job Title

  • Professor

J-Global ID

Research Interests

  • ナトリウム   機能性ガラス   ion exchange   ionic liquid   molten salts   化合物半導体   選択性電析   アルミニウムドロス   electrowinning   Bi-Sb-Te   passive film   鉄   ルミネッセンス   チタン   耐食性   光励起   ステンレス鋼   薄膜   水素貯蔵   耐食皮膜   溶融塩電解   水素化リチウム   

Research Areas

  • Nanotechnology/Materials / Metals and resources production
  • Nanotechnology/Materials / Inorganic compounds/materials chemistry
  • Nanotechnology/Materials / Material fabrication and microstructure control

Educational Organization

Association Memberships

  • THE ELECTROCHEMICAL SOCIETY   THE CHEMICAL SOCIETY OF JAPAN   日本工学教育協会   THE IRON AND STEEL INSTITUTE OF JAPAN   THE JAPAN INSTITUTE OF METALS   JAPAN SOCIETY OF CORROSION ENGINEERING   THE SURFACE FINISHING SOCIETY OF JAPAN   THE ELECTROCHEMICAL SOCIETY OF JAPAN   

Research Activities

Published Papers

  • Ibuki Sato, Koichiro Furusawa, Mikito Ueda, Hisayoshi Matsushima
    Fusion Engineering and Design 202 0920-3796 2024/05 
    Hydrogen isotopes will be new energy sources in nuclear fusion. In this study, a batch system for producing heavy water was developed in which pure water with deuterium (D) was circulated during proton exchange membrane water electrolysis. Deuterium was enriched by up to 94.7 at.% from 51.1 at.%. The D components of water and gas were analyzed during electrolysis. The relationship between the concentration of D (CD) and the electrolytic consumption ratio (R) was evaluated. This relationship was simulated using a mass balance model. From the gas analysis, the separation factor α was calculated. It was found that α depended on the ratio among H2O, HDO, and D2O to maintain the equilibrium state of the chemical exchange reaction.
  • Go Kamesui, Kei Nishikawa, Mikito Ueda, Hisayoshi Matsushima
    Journal of the Electrochemical Society 171 (4) 0013-4651 2024/04/01 [Refereed]
     
    Understanding electrolyte mass transfer during charge-discharge reactions is essential for developing next-generation storage batteries with high energy densities. In this study, we investigated Li+ transport in a highly concentrated electrolyte (HCE) consisting of an equimolar mixture of lithium bis(fluorosulfonyl)amide (LiFSA) and tetraglyme (G4) under current reversal and re-reversal. Concentration profiles of the electrolyte at a distance of 0-600 μm from the Li electrodes were obtained using in situ laser interferometry. The Li+ transference numbers and LiFSA diffusion coefficients were calculated from these profiles. Raman spectroscopy suggested that the coordination structure surrounding Li+ ions in the electrolytes mainly contributed to the transference number. A one-dimensional unsteady diffusion equation and the finite difference method were employed to simulate the concentration profiles. The maximum error percentage between the measured and simulated values was only 3%, confirming the accuracy and validity of the interferometric measurements. Our findings on Li-ion transfer in HCEs could promote the rational design of high-energy-density Li-ion batteries with higher cation transference numbers of electrolytes and charge-discharge rates.
  • Junji Nunomura, Hisayoshi Matsushima, Yoshihiko Kyo, Yoichi Kojima, Mikito Ueda
    Electrochimica Acta 460 0013-4686 2023/08/20 
    Recycling Al is crucial to reduce the energy and environmental costs of Al manufacturing; however, the reclamation efficiency of high-quality Al from Al alloys is limited by the co-deposition of impurities during the electrorefining process. To address this issue, the anodic dissolution behavior of metallurgical structures within various Al-Mn binary alloys in 1-ethyl-3-methyl-imidazolium chloride-AlCl3 ionic liquid was investigated. During the constant-potential electrolysis of Al-1.5%Mn cast and cold-rolled plate alloys, an enriched layer derived from Mn solid solution was formed at an electrorefining potential of 0.2 V; this was attributed to preferential dissolution of Al in the matrix phase, followed by Mn accumulation at the Al surface. Furthermore, dissolution of the Al-Mn-Fe and Al-Mn intermetallic compounds occurred at 0.6 and 1.0 V, respectively; thus, the dissolution behavior of Mn in the Al-Mn alloys differed between the Mn solid solution in the matrix phase and the Mn-containing intermetallic compounds. These results indicate that by controlling the microstructure of the Al-Mn alloy and the applied anodic potential, the dissolution of Mn into the 1-ethyl-3-methyl-imidazolium chloride-AlCl3 electrolyte can be suppressed, thus preventing its co-deposition with Al on the cathode. This development is therefore anticipated to inform the development of electrorefining processes to obtain high-quality recycled Al for numerous manufacturing applications.
  • Go Kamesui, Kei Nishikawa, Mikito Ueda, Hisayoshi Matsushima
    Electrochemistry Communications 151 1388-2481 2023/06 
    Next-generation Li-ion batteries (LIBs) require fast charge–discharge operations, during which a steep concentration gradient (CG) is formed between the two electrodes. The formation of a concentration profile between the electrodes in a LIB with a solvate ionic liquid is observed at a distance of less than 1 mm using holographic interferometry. This in situ technique enables the visualization of concentration profile formation near both electrodes during electrolysis, which relaxes after the electrolysis is stopped. The diffusion coefficients near both the electrodes are calculated from the concentrations of transient species near the electrode surfaces. The diffusion coefficient is smaller on the anode side of the cell than on the cathode side owing to the viscosity of the electrolyte in the diffusion layer. This viscosity effect may have caused the concentration profile to become asymmetrical during the relaxation of the CG.
  • Junji Nunomura, Hisayoshi Matsushima, Yoshihiko Kyo, Yoichi Kojima, Mikito Ueda
    Journal of the Electrochemical Society 170 (12) 0013-4651 2023 
    To produce over 99.9% of high-purity Al from Al alloys containing Al6Fe or β-AlFeSi through electrorefining, their anodic dissolution and cathodic electrodeposition characteristics should be clarified. In this study, the anodic dissolution and cathodic electrodeposition behavior of Al-Fe binary and Al-Fe-Si ternary alloys were investigated in an EmImCl-AlCl3 ionic liquid electrolyte at 323 K. Anodic polarization measurements, constant potential electrolysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission SEM (FE-SEM), and energy dispersive spectroscopy (EDS) were used to study the anode and electrodeposits on the cathode. Constant potential electrolysis showed that Fe dissolved from Al6Fe in the Al-Fe anode at 0.7 V vs Al/Al(III) and from β-AlFeSi in the Al-Fe-Si anode at 1.4 V and was co-deposited with Al on the cathode. Notably, Si did not dissolve from β-AlFeSi at either potential. A combination of controlled anodic dissolution potential and the use of the Al alloy containing β-AlFeSi further suppressed the dissolution and cathodic co-deposition of Fe, affording high-purity Al on the cathode. This suggests that Al alloys with intermetallic compounds that are less likely to dissolve Fe at the anode are optimal for obtaining over 99.9% of high-purity Al from Al alloys containing Fe in the electrorefining method.
  • Toranosuke Nago, Koichiro Furusawa, Mikito Ueda, Hisayoshi Matsushima
    International Journal of Hydrogen Energy 0360-3199 2023 
    Separation of hydrogen isotopes is an important process in materials science, biomedical research, and nuclear fields. In this study, we used a polymer electrolyte fuel cell to separate protium (H) and deuterium (D). Here a circulation system recycled hydrogen gas at the anode was used. H and D were enriched in the gas and water phases, respectively. The separation efficiency depends on the gas flow rate through the parameter λ, which describes the stoichiometric ratio of circulation gas to feed gas. H and D were simultaneously enriched in their respective phases. The circulation system prolonged the gas circulation time in the system to improve the separation efficiency.
  • Koichiro Furusawa, Toranosuke Nago, Mikito Ueda, Hisayoshi Matsushima
    International Journal of Hydrogen Energy 0360-3199 2023 
    Hydrogen isotope separation will be important for future hydrogen energy applications. The materials used in polymer electrolyte fuel cells (PEFCs), such as the hydrophobic support and Pt catalyst, are essentially the same to those used in the conventional isotope-separation method of water hydrogen chemical exchange. Hereby, deuterium (D) separation was performed with a PEFC. The separation was improved with increasing the water vapor and temperature. D was enriched into the dew water in the cell. The quantities of D conversion from the gas through the vapor to the dew water was measured. The conversion values were less than the simulated ones. This was attributed to the vapor pressure drop and the wetted catalyst surface by the water condensation.
  • Rei Esaki, Yohei Yasuda, Norito Kotani, Hisayoshi Matsushima, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 169 (8) 0013-4651 2022/08 
    Polyethylene glycol (PEG) plays an important role as an inhibitor of the electrodeposition. In this study, we investigated the potential dependence of PEG (molecular weight: 3000) adsorption and desorption processes on the gold single crystal substrate. High speed atomic force microscope (HS-AFM) was applied for observing the dynamic behaviors of the nucleation and the growth of PEG adsorption. The in situ observation was conducted at the several potentials where the cyclic voltammogram measurement showed the broad peak of the reduction current. As the applied potential became more cathodic, the adsorption morphology changed from film-like, through the sphere, to the large irregular cluster. When the potential was switched to anodic potential, HS-AFM could show the dissolution process of PEG. Finally we demonstrated the effect of the tip force by modifying the feed-back circuit of AFM.
  • Mashu Mita, Hisayoshi Matsushima, Mikito Ueda, Hiroshi Ito
    Journal of Colloid and Interface Science 614 389 - 395 0021-9797 2022/05/15 
    The nanobubbles (NB) formed on a solid surface has been reported, although the stability in a solution is still discussed. The atomic force microscopy (AFM) has shown the unique shape of the flatted NB, however the dynamic behavior has not investigated yet. Recently, the high scanning speed AFM (HS-AFM) has been developed and applied to the several interfaces. Here, we present in-situ HS-AFM observation during water electrolysis. The hydrogen and oxygen NB evolution on highly oriented pyrolytic graphite (HOPG) electrode are studied. Our video data is the first time to demonstrate the NB nucleation and the growth. The processes are different between both gases. The hydrogen NB grows with active coalescence, while the oxygen one is smaller and irregularly moves on HOPG surface. Using this technique, we will be able to study the NB stability influence by some factors, such as the surface potential and electric capillarity.
  • Go Kamesui, Kei Nishikawa, Mikito Ueda, Hisayoshi Matsushima
    ACS Energy Letters 7 (11) 4089 - 4097 2022 
    Understanding the mechanisms of electrodeposition and dissolution of Li metal is necessary to control the morphological variations of Li metal anodes for next-generation batteries. Herein, the morphology of electrodeposited Li in a sulfolane-based highly concentrated electrolyte (HCE) and its correlation with the concentration profiles close to the electrodes were investigated. The decomposition of the solvent and anions on the electrodeposited Li surface caused significant changes in the morphology and solid electrolyte interphase layer thickness. During electrochemical dissolution, the Li+ surface concentration at the electrode became supersaturated, and the number of anions coordinated to Li+ increased at high current densities. The supersaturation state induced divergence of the electrode potentials. Therefore, the electrode reaction progress is correlated with the mass transfer within HCEs. Understanding the relationship between mass transfer and morphological variation in the Li metal electrode should promote the development of a strategy for using HCEs in Li metal batteries.
  • Koichiro Furusawa, Toranosuke Nago, Mikito Ueda, Hisayoshi Matsushima
    International Journal of Hydrogen Energy 0360-3199 2022 
    Hydrogen isotopes are a valuable source of hydrogen energy through fusion reactions. The materials used in polymer electrolyte fuel cells (PEFCs), such as the hydrophobic support and Pt catalyst, are essentially the same to those used in the conventional isotope-separation method by water–hydrogen chemical exchange. Here, deuterium (D) separation was performed with a PEFC. A gas mixture of H2 and D2 was supplied while changing the humidity. The hydrogen gas and water vapor from the PEFC were analyzed to investigate the D mass balance. Without power generation, D was separated into the water vapor. This can be explained by the vapor-phase catalytic exchange reaction occurring on the platinum catalyst. The fuel-cell reaction enhanced D separation. A large amount of D (approximately 45%) was transferred to the water vapor during power generation. The present results demonstrate the synergistic effect of vapor-phase catalytic exchange and the PEFC on D separation.
  • Haruka Sato, Hisayoshi Matsushima, Mikito Ueda, Hiroshi Ito
    International Journal of Hydrogen Energy 46 (68) 33689 - 33695 0360-3199 2021/10/01 
    Water electrolysis (WE) is a key technology for a decarbonized society and is essential for hydrogen isotope separation for a future fusion reactor. In this study, deuterium (D) separation was performed by anion exchange membrane WE (AEMWE) and compared with our previous results from proton exchange membrane WE (PEMWE). WE allows D to become concentrated in solution and diluted in hydrogen gas compared with the D concentration in feed water. The separation effect increases with decreasing water stoichiometric ratio, λ, of the water feed to electrolysis volume. Owing to little water drainage from the cathode, AEMWE can be performed at λ ≈ 1.05, while λ ≈ 4.0 is the lowest for PEMWE. When the feed rate is reduced (λ < 2), D in the product water becomes more concentrated, which corresponds to a sharp rise in cell voltage owing to the water shortage at the cathode.
  • Tomoki Hirai, Hisayoshi Matsushima, Mikito Ueda
    Journal of the Electrochemical Society 168 (8) 0013-4651 2021/08 
    To investigate co-electrodeposition of Al and Sc ions, voltammogram measurements were carried out in LiCl-KCl molten salt containing AlCl3 and ScCl3 at 723 K. In the voltammogram measurements, a cathodic current of Al ions and formation of Al-Sc alloys were observed from 0 V and -0.2 V vs Al/Al(III), respectively. Sponge-like electrodeposit formed on the Cu substrate cathode under the condition of a constant potential electrolysis at -0.4 V. The contents of Al and Sc in the electrodeposit were 73.6 and 8.8 at% by EDS analysis. The X-ray diffraction pattern of the electrodeposit fits the patterns of Al and Al3Sc.
  • Akinori Miki, Kei Nishikawa, Go Kamesui, Hisayoshi Matsushima, Mikito Ueda, Michel Rosso
    Journal of Materials Chemistry A 9 (26) 15095  2050-7488 2021/07/14 
    The authors regret the misspelling of the name of one of the authors (Mikito Ueda) in the original manuscript. The corrected list of authors for this paper is as shown above. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.
  • Koichi Ui, Satoshi Kobayashi, Kuniaki Sasaki, Tatsuya Takeguchi, Tetsuya Tsuda, Mikito Ueda, Jyunji Nunomura, Yukio Honkawa, Yoichi Kojima
    Journal of The Electrochemical Society 2021/05/01
  • Tetsuya TSUDA, Kei HOSOYA, Mikito UEDA, Koichi UI, Masao MIYAKE, Junji NUNOMURA, Yoshiyuki OYA, Yoichi KOJIMA
    Denki Kagaku 89 (1) 27 - 31 2433-3255 2021/03/05
  • Go Kamesui, Kei Nishikawa, Hisayoshi Matsushima, Mikito Ueda
    Journal of The Electrochemical Society 168 (3) 031507 - 031507 0013-4651 2021/03/01 [Refereed]
     
    It is important to understand and control corrosion in very small parts. For this purpose, in situ observation of corrosion reactions is necessary. Magnetic fields offer a new way of influencing corrosion reactions. We have investigated the dissolution of a Cu anode in a magnetic field using a holographic laser interferometric microscope. The microscope enables us to quantify the growth of the diffusion layer and the variation in Cu2+ concentration in the vicinity of the electrode. By sandwiching the anode between two doughnut-shaped neodymium magnets, the increase in the surface concentration caused by dissolution is remarkably suppressed, whereas the thickness of the diffusion layer is barely affected. The present results support the hypothesis that mass transport in enhanced in the magnetic field.
  • Risako Tanii, Ryota Ogawa, Hisayoshi Matsushima, Mikito Ueda, Richard Dawson
    International Journal of Hydrogen Energy 46 (9) 6745 - 6750 0360-3199 2021/02/03 
    Fuel cells (FC) have been developed for automobiles and stationary power units. In addition to a power generator function, we propose a new application of hydrogen isotope separation. In this paper, deuterium (D) separation is investigated by two types of AFCs with platinum (Pt) or ruthenium (Ru) anode catalysts. The characteristics of the AFCs are evaluated by pure protium (H) or deuterium gas separately. In the case of Pt catalyst, the cell current/voltage curves show similar results for both gases. But a remarkable decrease in the voltage value is observed probably due to the mass transportation (diffusion) limitation at Ru catalyst. The limitation effect was larger for D2 than H2 gas. The AC impedance measurements supports the slow reaction rate of D2 gas on Ru catalyst. The separation experiments are verified with hydrogen gas mixed with 1 at% D. The D is diluted in the unreacted gas discharged from AFC with Pt catalyst, but it is concentrated with Ru one. The inverse response may be attributed to the elementary process of the hydrogen oxidation reaction and the difference in the adsorption energy of gas and water molecules on the catalyst surface.
  • Effects of water transport on deuterium isotope separation during polymer electrolyte membrane water electrolysis
    Kenji Harada, Risako Tanii, Hisayoshi Matsushima, Mikito Ueda, Koki Sato, Takahide Haneda
    International Journal of Hydrogen Energy 45 31389 - 31395 2020/11 [Refereed]
  • Effect of high magnetic field on aluminum electrodeposition using an ionic liquid
    Hisayoshi Matsushima, Hitomi Takahashi, Tatsuki Suzuki, Mikito Ueda, Iwao Mogi
    Electrochemistry Communications 115 106733  2020/10 [Refereed][Not invited]
  • Koichi Ui, Satoshi Kobayashi, Tatsuya Takeguchi, Tetsuya Tsuda, Mikito Ueda, Jyunji Nunomura, Yukio Honkawa, Yoichi Kojima
    ECS Transactions 2020/09/23 [Refereed][Not invited]
  • Corrosion behavior of SUS304L Steel in pH 13 NaOH Solution
    T. Nakagawa, H. Matsushima, M. Ueda, H. Ito
    Electrochemistry 88 468 - 474 2020/08 [Refereed][Not invited]
  • In Situ Measurement of Al3+ concentration Profile during Al Anodization using Degital Holographic Interferometic Microscope
    Akinori Miki, Kei Nishikawa, Takahiro Ozawa, Hisayoshi Matsushima, Mikito Ueda
    J. Electrochem. Soc. 167 062501  2020/05 [Refereed][Not invited]
  • Aluminium-Poly(3,4-ethylenedioxythiophene) Rechargeable Battery with Ionic Liquid Electrolyte
    T. Shoetz, Ben Craig, Carlos Ponce de Leon, Andreas. Bund, Mikito. Ueda, Chee Tong John Low
    Journal of Energy Strage 28 101176  2020/03 [Refereed][Not invited]
  • 補助電極を用いたEmImCl-AlCl3イオン液体からの光沢アルミニウム電解めっき膜とそのアルマイト処理
    平井友樹, 松島永佳, 上田幹人
    表面技術 71 (1) 32 - 36 2020/01 [Not refereed][Not invited]
  • Daiki Nakajima, Tatsuya Kikuchi, Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda, Ryosuke O. Suzuki, Shungo Natsui
    Materials 12 3497  2019/11 [Refereed][Not invited]
  • Hisayoshi Matsushima, Ryota Ogawa, Mikito Ueda
    International Journal of Hydrogen Energy 44 (29) 15436 - 15440 0360-3199 2019/06/07 
    © 2019 Hydrogen Energy Publications LLC The separation of hydrogen isotopes has important applications for fundamental science and nuclear engineering. This study investigates isotope separation by stacked polymer electrolyte fuel cells that form part of a combined electrolysis and fuel cell (CEFC) system. Fuel gas containing deuterium (D) was generated by water electrolysis and passed through three fuel cells (FCs) connected in series. Increasing the number of operating FCs in the series greatly improved D separation, but had only a modest impact on power consumption. When all three FCs were individually controlled, the separation efficiency depended on the power condition in each FC. At high current the separation factor of the CEFC system reached over 100 owing to the relationship between fuel gas utilization and separation efficiency.
  • Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda
    Electrochimica Acta 302 422 - 427 0013-4686 2019/04 
    © 2019 Elsevier Ltd We studied the early stages of Cu electro-deposition and -dissolution on Au(111) over a wide overpotential regime by using high speed atomic force microscopy (HS-AFM) with a high temporal resolution. The HS-AFM images revealed an instantaneous nucleation mechanism where epitaxial nuclei were created at a low cathode overpotential. Nuclei with straight edges were caused by the influence of the Au(111) lattice, whereas arched and uneven edges were associated with rapid structural fluctuations of Cu adatoms. For deposits formed at a high overpotential, many fine column-like deposits covered the whole surface plane and the number of Cu nuclei increased with the cathode overpotential. These features were related to the masstransportation. Furthermore, we observed small clusters, a few nm in size, which remained on the substrate after the rapid dissolution process.
  • Takahiro Matsuzaki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi, Mikito Ueda
    Materials Transactions 60 (3) 386 - 390 2019/03 [Refereed][Not invited]
  • Takahiro Matsuzaki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi, Mikito Ueda
    Materials Transactions 60 (3) 411 - 415 2019/03 [Refereed][Not invited]
  • Kei Nishikawa, Takaki Saito, Hisayoshi Matsushima, Mikito Ueda
    Electrochimica Acta 297 1104 - 1108 0013-4686 2019/02/20 
    © 2018 Elsevier Ltd We measured the concentration boundary layer during copper electrodeposition in a copper sulfate solution under an applied magnetic field. Using a holographic laser interference microscope, we demonstrated the formation of the diffusion layer near the cathode. In the initial stage of electrodeposition, the diffusion layer was distorted in a magnetic field. An analysis of the electrode surface concentration supported the following assertions: without a magnetic field, dendrites formed when the surface concentration of Cu2+ was depleted; with a magnetic field, the unique convection phenomena of the field gradient force and localized Lorentz force promoted Cu2+ mass transport in the diffusion layer, producing large crystal grains.
  • Kojima Yoichi, Tsuda Tetsuya, Ui Koichi, Ueda Mikito, Miyake Masao
    Journal of Japan Institute of Light Metals 一般社団法人 軽金属学会 69 (1) 15 - 21 0451-5994 2019/01/30 [Not refereed]
  • Risako Tanii, Ryota Ogawa, Hisayoshi Matsushima, Mikito Ueda
    International Journal of Hydrogen Energy 44 (3) 1851 - 1856 0360-3199 2019/01/15 
    © 2018 Hydrogen Energy Publications LLC Processes for separating hydrogen isotopes are important for future energy applications. Several separation methods are based on electrolytic process; however, electrolysis consumes large amounts of electric energy. In this study, we demonstrate deuterium isotope separation from a mixture of H 2 and D 2 gases using a polymer electrolyte fuel cell stack. To identify the most efficient process, we investigated two flow patterns for the fuel gas, namely, parallel and serial flow. The electrical power of the stacks depended on the flow pattern when a high current was generated. We attribute this dependence on membrane dehydration and water droplet formation in the serial flow, which passed through the single cells in a straight path. However, the stack with the serial path showed a high separation factor (α = 6.6) indicating enrichment of deuterium water during the operation. The long reaction path of the fuel gas contributed to effective separation. The fuel utilization in individual cells suggested the potential for even more effective separation processes by a serial flow path.
  • Hisayoshi Matsushima, Hanako Sato, Mikito Ueda, Hiroshi Ito
    Journal of the Electrochemical Society 166 (10) F566 - F568 0013-4651 2019 
    © 2019 The Electrochemical Society. Electrolytic deuterium (D) separation from protium-containing solution has been investigated. Proton (PEM) and anion exchange membrane (AEM) electrolysis were performed at constant current. The mass analysis of hydrogen gas and water vapor was carried out. For both PEM and AEM electrolysis, the D concentration in the evolved hydrogen gas was lower than that of the initial electrolytic solution. The D concentration in the water vapor was unchanged by PEM electrolysis, but was increased by AEM. The separation factor of PEM was smaller than that of AEM, which was attributed to the humidification state on platinum catalyst.
  • Shota Kaneko, Hisayoshi Matsushima, Mikito Ueda
    Keikinzoku/Journal of Japan Institute of Light Metals 69 (1) 42 - 45 0451-5994 2019 
    © 2019 The Japan Institute of Light Metals. To form Al-Mn-Zn ternary alloy film, electroplating experiments were carried out in low temperature AlCl 3 - NaCl-KCl molten salt at 423 K. In voltammogram measurement, Mn ions were reduced with Al ions at lower than -0.08 V vs. Al/Al(III) in AlCl 3 -NaCl-KCl melt containing MnCl 2 . Zn ions reduction started at 0.2 V in the melt containing ZnCl 2 and the reduction current increased with increasing ZnCl 2 concentration. Compositions of Al-Mn-Zn alloy were changed by ZnCl 2 concentration and electrolysis potential. A relatevely glossy surface was formed in 91at%Al-8at%Mn-1at%Zn alloy and a dull surface was formed in 90at%Al-8at%Mn-2at%Zn alloy. In XRD measurement, intensity of amorphous phase decreased with increasing Zn concentration in the alloys.
  • Yoichi Kojima, Tetsuya Tsuda, Koichi Ui, Mikito Ueda, Masao Miyake
    Journal of the Japan Institute of Light Metals 69 (1) 15 - 21 2019/01 [Refereed][Invited]
  • Interaction of Localized Surface Plasmons of a Silver Nanosphere Dimer Embedded in a Uniform Medium: STEM-EELS and DDA Simulation
    N. Sakaguchi, S. Matsumoto, Y. Kunisada, M. Ueda
    The Journal of Physical Chemistry C 123 6735 - 6744 2019 [Refereed][Not invited]
  • Ryota Ogawa, Risako Tanii, Richard Dawson, Hisayoshi Matsushima, Mikito Ueda
    Energy 149 98 - 104 0360-5442 2018/04/15 [Refereed][Not invited]
     
    The framework about combined electrolysis fuel cell (CEFC) was reported previously [H. Matsushima et al., Energy, 2005 30 2413]. The purpose of the present study focused on measuring the separation factor and the energy reduction by assembling CEFC system. The separation of deuterium was studied with a 1-M KOH electrolyte containing 10 at% deuterium. Polarization plots of alkaline water electrolysis (AWE) revealed relationships between the catalytic activity of the hydrogen evolution reaction and the deuterium separation factor. The power loss was mainly attributed to gas bubble evolution. For polymer electrolyte fuel cells (PEFCs) with a Pt catalyst, approximately 21% of the electrical energy could be recovered by reusing hydrogen gas produced by the AWE. Furthermore, the PEFC could efficiently dilute protium in the gas phase, resulting in a high separation factor of 30.2 for the CEFC.
  • T. Schoetz, C. Ponce de Leon, A. Bund, M. Ueda
    Electrochemistry Communications 89 52 - 56 1388-2481 2018/04/01 [Refereed][Not invited]
     
    This work shows the electro-polymerisation of thin film poly(3,4-ethylenedioxythiophene) on three-dimensional reticulated vitreous carbon substrates by cyclic voltammetry and pulsed polymerisation methods from a Lewis neutral chloroaluminate ionic liquid containing 3,4-ethylenedioxythiophene monomer. The polymer composite is attractive as an energy storage electrode for sustainable and high-performance technologies due to its unique properties of battery and capacitor in one system, i.e., the redox reaction occurring simultaneously with the anion doping/de-doping of the conductive polymer with AlCl4 − ionic species contained in the ionic liquid. The structure of the polymer films, their doping/de-doping mechanism and the stability in the ionic liquid were characterised by scanning electron microscopy and cyclic voltammetry and compared with films electro-polymerised on planar vitreous carbon. The typical granular and nano/micro-porous polymer structure observed on planar vitreous carbon was successfully replicated on the macro-porous reticulated vitreous carbon surface. The polymer films show approximately 45% higher capacity than films on planar substrates and similar efficient redox behaviour, proving that the material has hybrid battery-capacitor properties enhanced by the higher area per unit volume of reticulated vitreous carbon.
  • T. Schoetz, C. Ponce de Leon, A. Bund, M. Ueda
    Electrochimica Acta 263 176 - 183 0013-4686 2018/02/10 [Refereed][Not invited]
     
    This work studied the electro-polymerisation of 3,4-ethylenedioxythiophene (EDOT) and its electrochemical behavior in Lewis acidic, neutral and basic chloroaluminate ionic liquid 1-ethyl-3-methylimidazolium chloride aluminum chloride (EMImCl-AlCl3) by cyclic voltammetry. It was found that the electro-polymerisation on vitreous carbon only occurs in Lewis neutral EMImCl-AlCl3 as a dark blue-violet film whereas the electro-polymerisation in a Lewis acidic or basic compositions is not possible due to the interactions between the conductive polymer and the ionic liquid as well as the potential stability limits of the electrolyte. PEDOT films synthesised in Lewis neutral ionic liquid were tested in monomer-free Lewis acidic, basic and neutral EMImCl-AlCl3 and show different doping and de-doping behavior for chloride ionic species. The PEDOT films in a Lewis neutral composition showed higher doping levels due to the higher potential stability window, up to 2.6 V vs. Al|Al(III) than in a Lewis acidic and basic solutions. Furthermore, it was shown that the doping and de-doping levels are predefined during the electro-polymerisation of PEDOT. The anion doping and de-doping reaction reached 97% reversibility in the neutral composition, which suggests that PEDOT is a suitable electrode material to store charged species in this media and could be used in rechargeable energy storage devices.
  • Removal of Ca and K from Metallic Na in TFSI Ionic Liquids Using an Exchange Reaction
    S.Mizukami, H. Matsushima, M.Ueda
    J. Electrochem. Soc. 165 D94 - D97 2018/02 [Refereed][Not invited]
  • Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda
    Electrochemistry Communications 92 29 - 32 1388-2481 2018 [Refereed][Not invited]
     
    © 2018 Elsevier B.V. The initial stages of Cu electrodeposition and dissolution on an Au(100) electrode in sulfuric acid solution were studied by high-speed atomic force microscopy. Dynamic observations revealed that Cu islands formed on the Au terraces within a few seconds. The islands grew to approximately 100 nm as two thick layers overlapped. The AFM height profile results indicated that each layer consisted of 3–8 atomic layers. Dissolution occurred when an anodic potential was applied, with the bottom layer dissolved preferentially. Correlation of these observations with electrochemical data from cyclic voltammetry indicated differences in the rates of deposition and dissolution.
  • Understanding the charge storage mechanism of conductive polymers as hybrid battery-capacitor materials in ionic liquids by in-situ atomic force microscopy and electrochemical quartz crystal microbalance studies
    T. Shoetz, M. Kuruniawan, M. Stich, R. Peipmann, I. Efimov, A. Ispas, A. Bund, P.D. Leon, M. Ueda
    Journal of Materials Chemistry A6 17787 - 17799 2018 [Refereed][Not invited]
  • Mikito Ueda, Shiori Honda, Hisayoshi Matsushima
    Electrochemistry 86 (2) 69 - 71 2186-2451 2018 [Refereed][Not invited]
     
    To enhance three phase interfaces on graphite cathodes in an Al-Cl2 cell, graphite cathodes with different densities (1.27, 1.32, 1.40, 1.57, and 2.00gcm-3) were evaluated in an 1-ethyl-3-methylimidazolium chloride -AlCl3 mixture ionic liquid electrolyte at 313 K. The relation between current and cell voltage or power and current of the 1.27gcm-3 graphite cathode showed the best performance among the graphite materials with 5 graphite densities in the cathodes investigated here. Surface profiles of the graphite by mercury intrusion porosimetry suggested that there are effective pore diameters for penetration of the electrolyte, lower density graphite has more pores on the surface than graphite with higher densities.
  • Masato Onishi, Hisayoshi Matsushima, Mikito Ueda, Kota Washio, Akira Kato
    Electrochemistry 86 (2) 66 - 68 2186-2451 2018 [Refereed][Not invited]
     
    To clarify the relationship between adhesive strength of Al electroplating film and Mg alloy substrate, the amounts of γ-phase (Mg17Al12) and α-phase (Mg solid solution phase) in Mg alloy surface was investigated. Al electroplating film on Mg alloy was formed by current pulse electrolysis in AlCl3-1-ethyle-3-methyl-imidazolium chloride mixture ionic liquid at 283 K. It was found that the adhesive strength was affected by the ratio of γ-phase in the Mg alloys and it increased with increasing ratios of γ-phase on the Mg alloy surface. The results suggest that the adhesive strength of the electrodeposits on the γ-phase is stronger than that of the α-phase due to little oxide formation on the γ-phase.
  • T. Schoetz, M. Ueda, A. Bund, C. Ponce de Leon
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 21 (11) 3237 - 3246 1432-8488 2017/11 [Refereed][Not invited]
     
    This paper presents a feasibility study of a non-aqueous rechargeable battery based on aluminum and poly-(3,4-ethylenedioxythiophene) conductive polymer in a chloroaluminate ionic liquid. The polymer was electrodeposited on a vitreous carbon working electrode in a chloride aqueous solution and the structure was analyzed by scanning electron microscopy. The doping/de-doping mechanism of chloride ions into the polymer structure was studied using a quartz crystal microbalance and cyclic voltammetry. The deposition/dissolution of the aluminum negative electrode were investigated by electrochemical and microscopic methods. Performance data were obtained with a laboratory-scale aluminum-conductive polymer battery at constant current showing an average cell discharge voltage of 1 V and specific energies of at least 84 Wh kg(-1) referred to the mass of the polymer and aluminum. The system is novel and the paper outlines further research to improve the cell performance.
  • Hisayoshi Matsushima, Ryota Ogawa, Shota Shibuya, Mikito Ueda
    MATERIALS 10 (3) 303  1996-1944 2017/03 [Refereed][Not invited]
     
    The use of a polymer electrolyte fuel cell (PEFC) with a Nafion membrane for isotopic separation of deuterium (D) was investigated. Mass analysis at the cathode side indicated that D diffused through the membrane and participated in an isotope exchange reaction. The exchange of D with protium (H) in H2O was facilitated by a Pt catalyst. The anodic data showed that the separation efficiency was dependent on the D concentration in the source gas, whereby the water produced during the operation of the PEFC was more enriched in D as the D concentration of the source gas was increased.
  • Mikito Ueda
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 21 (3) 641 - 647 1432-8488 2017/03 [Refereed][Invited]
     
    Studies using low-temperature chloroaluminate molten salts are introduced. The physical and chemical properties have been elucidated from around the 1930s, and electrodeposition of Al alloys was reported more recently. Electrodeposition of Bi, Sb, and Te using an AlCl3-NaCl-KCl molten salt is also introduced as an application of molten salts.
  • T. Schoetz, C. Ponce De Leon, M. Ueda, A. Bund
    Journal of the Electrochemical Society 164 (14) A3499 - A3502 1945-7111 2017 [Refereed][Not invited]
     
    The main challenges to implement sustainable energy storage technologies are the utilization of earth-abundant recyclable materials, low costs, safe cell reactions and high performance, all in a single system. Aluminum batteries seem to cover these requirements. However, their practical performance is still not comparable with the state of the art high performance batteries. A key aspect to further development could be the combination of aluminum with charge storage materials like conductive polymers in non-aqueous electrolytes taking advantage of the properties of each material. This reviewpresents the approaches and perspectives for rechargeable aluminum-based batteries as sustainable high-performance energy storage devices.
  • 高橋久智美, 行方千賀, 菊地竜也, 松島永佳, 上田幹人
    表面技術 表面技術協会 68 (4) 208 - 212 0915-1869 2017 [Refereed][Not invited]
  • Hitomi Takahashi, Hisayoshi Matsushima, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 164 (8) H5165 - H5168 0013-4651 2017 [Refereed][Not invited]
     
    The surface structure of Al films electrodeposited in a magnetic field was studied in a AlCl3-1ethyl-3methylimidazolium chloride (EMIC) mixture ionic liquid, focusing on the surface morphology and crystal orientation. Current-dependent measurements reveal two preferential orientations. First, at small current densities (i < 10 mA cm(-2)), a (111) plane is preferentially oriented parallel to the surface where no magnetic field is detected. Second, at high current densities (i > 10 mA cm(-2)), a (200) plane is selectively grown, where the mass transportation of Al(III) is promoted by magneto-hydrodynamic (MHD) convection. Correlations of these data with scanning electron microscope observations showing tabular-facet formation in the magnetic field suggest that these structural variations are induced by microscopic MHD, demonstrating the difference between this process and that existing in an aqueous system. (C) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.
  • Ellipso-Microscopic Observation of Titanium Surface under UV-Light Irradiation
    K. Fushimi, K. Kurauchi, T. Nakanishi, Y. Hasegawa, M. Ueda, T. Ohtsuka
    Corrosion Science and Technology 16 (2) 265 - 270 2017 [Refereed][Not invited]
  • Kazuki Sato, Hisayoshi Matsushima, Mikito Ueda
    APPLIED SURFACE SCIENCE 388 (B) 794 - 798 0169-4332 2016/12 [Refereed][Not invited]
     
    To form Al-Ta alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KClmelt containing TaCl5 at 423 K. The voltammogram showed two cathodic waves at 0.45 V and 0.7 V vs. Al/Al(III), which may correspond to reduction from Ta(V) to Ta(III) and from Ta(III) to tantalum metal, respectively. Electrodeposits of Al and Ta were obtained in the range from 0.05 to 0.3 V and the highest concentration of Ta in the electrodeposit was 72 at% at 0.3 V. With increasing Ta content in the alloy, the morphology of the electrodeposits became powdery and the particle size smaller. (C) 2016 Elsevier B.V. All rights reserved.
  • Ryota Ogawa, Hisayoshi Matsushima, Mikito Ueda
    ELECTROCHEMISTRY COMMUNICATIONS 70 5 - 7 1388-2481 2016/09 [Refereed][Not invited]
     
    The separation of deuterium from a hydrogen-deuterium mixture was carried out using an alkaline membrane fuel cell (AMFC) with a Pt catalyst. This novel use of an AMFC to separate deuterium from a mixture of H-2 and D-2 was demonstrated by the production of deuterium-enriched water during power generation by the AMFC. The deuterium separation factor increased with output current (i) to a maximum value of 1.64 attained at i = 30 mA cm(-2). (C) 2016 Elsevier B.V. All rights reserved.
  • Kazuki Sato, Hisayoshi Matsushima, Mikito Ueda
    MOLTEN SALTS AND IONIC LIQUIDS 20 75 (15) 305 - 312 1938-5862 2016 [Refereed][Not invited]
     
    To form Al-W alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KCl melt containing WCl4 at 423 K. The voltammogram showed two cathodic waves at 1.1 V and 0.5 V vs. Al/Al(III), which may correspond to the reduction from W(IV) to W(III) and from W(III) to tungsten metal, respectively. Electrodeposits of Al and W were obtained in the range from -0.05 to 0.4 V and the highest concentration of W in the electrodeposit was 95 at% at 0.4 V. With increasing W content in the alloy, the morphology of the electrodeposits became more powdery and the particle size smaller.
  • Masato Onishi, Hisayoshi Matsushima, Mikito Ueda, Hiroki Habazaki, Kota Washio, Akira Kato
    ECS Transactions 75 (15) 297 - 304 1938-6737 2016 [Refereed][Not invited]
     
    To investigate the relationship between adhesion strength of Al electroplated film and Al concentration in Mg alloy substrates and the grain size of the Mg alloy, Al electroplating was carried out with AZ31, AZ61, AZ91, and of AZ31 with different grain sizes in an ionic liquid of a mixture of aluminum chloride and 1-ethyle-3-methyl-imidazolium chloride at 283 K. Dense Al electrodeposits were formed on all the substrates. The adhesion strength increased with increases in the Al content of the Mg alloys. Increasing the average grain size also resulted in increases in the adhesive strength.
  • Hitomi Takahashi, Chika Namekata, Tatsuya Kikuchi, Hisayoshi Matsushima, Mikito Ueda
    Journal of Surface Finishing Society of Japan 68 208 - 212 2016 [Refereed][Not invited]
  • Utalization of Ionic liquids as electrolyte for electrodeposition of metal and alloys
    Mikito Ueda
    Journal of Surface Finishing Society of Japan 67 6 - 9 2016 [Refereed][Invited]
  • Toshiaki Ohtsuka, Mikito Ueda, Masatoshi Abe
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 163 (8) C459 - C469 0013-4651 2016 [Refereed][Not invited]
     
    The passive oxide film on SUS 304 stainless steel (SS) was studied in a 0.1 mol dm(-3) sulfuric acid solution as a function of passivation time. The passive oxide films were measured by ellipsometry and X-ray photoelectron spectroscopy (XPS). A Mott-Schottky plot of the film capacitance was employed to determine the donor density in the n-type semiconducting oxide film, and current measurements of the Fe3+/Fe2+ redox couple were employed to investigate the electronic transfer process on the passive oxide film. The passive oxide consists of Cr-Fe-Ni oxides in which enrichment of Cr to 57 mol% occurs as the potential increases. During the aging of the passive oxide at 0.6 V vs. Ag/AgCl/saturated KCl (SSC) for 43 ks, the current decreased from 30 mu A cm(-2) at 10 s to 0.025 mu A cm(-2) at 43 ks, and the Cr ratio in the oxide increased from 49 to 57 mol% with an increase in the O2- ratio. Notably, the film thickness remained nearly constant at 1.3 nm during the aging process. Enrichment of the Cr content resulted in a decrease in the donor density of the n-type semiconducting passive oxide and the inhibition of electronic charge transfer from/to the Fe3+/Fe2+ redox couple in the electrolyte. (C) The Author(s) 2016. Published by ECS.
  • Shota Shibuya, Hisayoshi Matsushima, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 163 (7) F704 - F707 0013-4651 2016 [Refereed][Not invited]
     
    Hydrogen evolution and oxidation reactions were studied on a polycrystalline platinum electrode in 0.05 M D2SO4 solution at 298 K by using a rotating disk electrode, focusing on the kinetic isotope effect on reactivity. The polarization measurements in the evolution reaction regime, on the one hand, revealed two Tafel regions: at low overpotentials close to the equilibrium potential, the Tafel slope was 0.039 V dec(-1), suggesting a Volmer-Tafel mechanism; and at potentials around 0.05 V or lower, a slope of 0.168 V dec(-1) indicated that a transition to a Heyrovsky-Tafel mechanism occurred. In the oxidation reaction regime, on the other hand, a single Tafel slope of 0.055 V dec(-1) was observed at potentials of 0.08 V or lower. Comparing between the deuterium and protium data for the kinetic factors supported the presence of an isotope effect, whereby the deuterium was more easily dissociated on the platinum electrode. The present kinetic result supported the deuterium separation of polymer electrolyte fuel cell (PEFC) in which the mixture gases of H-2 and D-2 were purged. The deuterium separation factor increased with increasing in the hydrogen utilization. This suggests a new isotope separation technique and also provides useful data for fuel cells. (C) 2016 The Electrochemical Society. All rights reserved.
  • K. Fushimi, K. Kurauchi, H. Ikeyama, Y. Kitagawa, T. Nakanishi, Y. Hasegawa, M. Ueda, T. Ohtsuka
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 19 (12) 3579 - 3587 1432-8488 2015/12 [Refereed][Not invited]
     
    Photo-corrosion of an anodized titanium surface in 0.05 mol dm(-3) sulfuric acid solution was investigated by using an in situ electrochemical ellipso-microscope. Irradiation of ultra-violet (UV) light on an anodized surface, which showed a patch-like bright image on an ellipso-microscopic view due to non-uniform growth of the oxide film, under potentiostatic polarization allowed the flow of a photo-induced anodic current and changed the brightness and patch pattern in the image. This indicates that the irradiation promotes photo-electrochemical reaction, resulting in a change in the thickness and/or structure of the oxide film on the surface. The film change was dependent not only on power density of the irradiation light but also on applied potential during the irradiation and crystallographic orientation of the substrate. Pitting initiation during potentiodynamic polarization in the acid with bromide ions was also monitored using the ellipso-microscope. The irradiation resulted in pitting initiation at lower potentials than those in a non-irradiated condition.
  • Mikito Ueda, Tsubasa Teshima, Hisayoshi Matsushima, Toshiaki Ohtsuka
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 19 (12) 3485 - 3489 1432-8488 2015/12 [Refereed][Not invited]
     
    To improve the corrosion resistance of Al in chloride solutions, electrodeposition of Al-Zr alloys of various compositions was carried out at 448 K by constant potential control in AlCl3-NaCl-KCl molten salt containing ZrCl4. Cathodic reduction of the Zr ions starts at a potential of 0.4 V vs. Al/Al(III) in the molten salt. The electrodeposition of Al and Zr occurred at potentials more negative than -0.02 V. The concentration of Zr in the electrodeposit increased to 23 at.% at -0.02 V. In the XRD analysis, the electrodeposits formed at -0.05 to -0.15 V had good crystallinity, the electrodeposits containing higher concentrations of Zr formed at -0.02 or -0.04 V show an amorphous or fine crystal structure. The pitting potentials of Al-Zr alloys containing 5-23 at.% Zr in 0.1 M NaCl solution shifted from +0.1 to +0.3 V compared with those of pure Al.
  • Yu Hang, Hiroki Murakoshi, Mikito Ueda, Kazuhisa Azumi
    SURFACE & COATINGS TECHNOLOGY 270 164 - 169 0257-8972 2015/05 [Refereed][Not invited]
     
    An intermediate protective layer of Zn was formed on the AZ91D surface to prevent dissolution of the substrate surface and to obtain a uniform deposition layer of Al in an electroplating process from a molten salt bath. Simple zincate treatment did not result in the formation of a Zn layer with sufficient thickness and coverage for substrate protection. Electrodeposition of Zn was thus conducted after the zincating process to thicken the Zn layer. A Zn layer of a few pm irtthickness sufficiently protected the AZ91D substrate. A uniform Al layer was then electrode-posited on Zn-protected AZ91D without degradation of the substrate. Since the Mg alloy surface and Zn surface were not sufficiently active for Zn deposition and Al deposition, respectively, Cu-nanoparticle predeposition was applied to each surface before the electrodeposition processes. (C) 2015 Elsevier B.V. All rights reserved.
  • Tatsuya Kikuchi, Ryoma Ishida, Shungo Natsui, Takehiko Kumagai, Isao Ogino, Norihito Sakaguchi, Mikito Ueda, Ryosuke O. Suzuki
    ECS SOLID STATE LETTERS 4 (9) M19 - M22 2162-8742 2015 [Refereed][Not invited]
     
    The novel fabrication of multi-walled carbon nanotube (MWCNT)/cementite (Fe3C) nanocomposites was demonstrated via the calciothermic reduction of carbon dioxide (CO2) through electrolysis in molten CaCl2/CaO with iron additives at 1173 K. In this technique, CO2 generated from a graphite anode is reduced to carbon with a metallic calcium reductant formed on a graphite cathode via electrolysis in molten salt. Calciothermic reduction without iron additives resulted in the formation of onion-like carbons (OLCs) with spherical graphite layers and thin graphite sheets. In contrast, MWCNT/Fe3C nanocomposites and OLCs were successfully fabricated via calciothermic reduction with iron additives through their catalytic activities. (C) The Author(s) 2015. Published by ECS. All rights reserved.
  • Mikito Ueda, Ryuichi Inaba, Hisayoshi Matsushima, Toshiaki Ohtsuka
    ECS ELECTROCHEMISTRY LETTERS 4 (2) E1 - E3 2162-8726 2015 [Refereed][Not invited]
     
    To develop an electrorefining process for sodium to enable recycling of used sodium-sulfur batteries, a non-aqueous electrolyte with low melting point was investigated. A mixed ionic liquid of NaTFSI (sodium bis(trifluoromethane) sulfonylimide) - TBATFSI (tetrabutylammonium bis(trifluoromethane) sulfonylimide) was selected for the electrolyte. From AC impedance measurements, a maximum ionic conductivity of 16 mS cm(-1) was established of 20 mol% NaTFSI-TBATFSI concentration at 433 K. Electrorefining for 20 hours was carried out with a stable voltage under constant current electrolysis. Liquid pure sodium was electrodeposited by the constant current electrolysis. The calcium content in the sodium cathode was decreased from 250 to 52 ppm by the electrorefining. (C) 2014 The Electrochemical Society. All rights reserved.
  • Hisayoshi Matsushima, Wataru Majima, Yasuhiro Fukunaka, Mikito Ueda
    ECS ELECTROCHEMISTRY LETTERS 4 (7) F43 - F45 2162-8726 2015 [Refereed][Not invited]
     
    Controlling the wetting properties at the three-phase interface is important for improving the performance of alkaline fuel cells. The meniscus of a potassium hydroxide droplet was formed on a nickel electrode, and the interference fringe during the oxygen reduction reaction was observed by confocal laser microscopy. The high spatial resolution of the microscope revealed thin film formation at the meniscus front interface. The thickness decreased with increasing cathodic potential. The generation of microscopic convection by interfacial surface tension may affect mass transfer in the thin film. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.
  • Nan Sheng, Yanhua Lei, Atsushi Hyonoo, Mikito Ueda, Toshiaki Ohtsuka
    PROGRESS IN ORGANIC COATINGS 77 (11) 1724 - 1734 0300-9440 2014/11 [Refereed][Not invited]
     
    To improve the protection against the corrosion of AZ91D magnesium alloy provided by conducting polypyrrole (PPy) films, optimization of the electrochemical synthesis of the PPy film was investigated. The bi-layered PPy film was prepared under constant current control, first in a sodium tartrate solution containing molybdate and second in a sodium dodecylsulfate (DS) solution (after the AZ91D alloy was covered by zinc electroplating). Corrosion testing of the zinc-coated AZ91D alloy covered with the PPy film was performed in 3.5% NaCl solution. The more protective PPy film doped with tartrate ions (PPy-Tart film) was formed by the lower current density (CD). Doping of molybdate ions (MoO42-) into the PPy-Tart film significantly improved its corrosion protection properties. When the PPy-Tart-MoO4 layer was covered by an outer PPy layer doped with DS ions, the corrosion protection was further improved. The imposition of ultrasonic waves during the electropolymerization of the inner PPy-Tart-MoO4 layer was effective in the improvement of corrosion protection. The bi-layered PPy-Tart-MoO4/PPy-DS film prepared under ultrasonic irradiation maintained the zinc-coated AZ91D alloy in the passive state during the corrosion test in NaCl solution for 221 h, during which no corrosion products appeared. (C) 2014 Elsevier B.V. All rights reserved.
  • Junji Nunomura, Mikito Ueda, Toshiaki Ohtsuka
    ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS 228 (6-7) 685 - 689 0942-9352 2014/07 [Refereed][Not invited]
     
    To improve the reduction efficiency of chlorine electrodes in aluminum-chlorine cells, this reports a circular cone type graphite cathode, with an electrochemical cell consisting of an aluminum anode and the graphite cathode evaluated in EMIC-AlCl3 ionic liquid. The current density in the circular cone type cathodes with different cone angles exhibited a maximum value at 40, and the current density at cell voltage of 0.5 V was about 25 mA cm(-2). This value is about 80% larger than that of a cylindrical type graphite cathode. In a circular cone type cathode with a 40 angle, the maximum power density recorded was 15.3 mW cm(-2).
  • YanHua Lei, Nan Sheng, Atsushi Hyono, Mikito Ueda, Toshiaki Ohtsuka
    PROGRESS IN ORGANIC COATINGS 77 (4) 774 - 784 0300-9440 2014/04 [Refereed][Not invited]
     
    Polypyrrole (PPy) films were deposited on copper from "green" inhibitor of phytic acid solution for corrosion protection of copper. The corrosion protection property of the PPy layer was studied by an immersion test in a NaCl aqueous solution. The polymerization process of PPy on copper changed with the pH values of phytic acid solution and current density applied. When one oxidized bare copper in phytic acid solution at various pHs containing pyrrole monomer, a thin layer consisting of complex compound of Cu-phytate was firstly formed, followed by the formation of the PPy layer doped with phytate anion on the complex compound layer. The complex compound layer passivated the copper surface and its thickness increased with the lower pH value of the solution and the lower current density applied. It was found that the PPy coating prepared in the phytic acid solution at pH 4 exhibit the most protective property against copper corrosion. (C) 2014 Elsevier B.V. All rights reserved.
  • Y. H. Lei, N. Sheng, A. Hyono, M. Ueda, T. Ohtsuka
    PROGRESS IN ORGANIC COATINGS 77 (2) 339 - 346 0300-9440 2014/02 [Refereed][Not invited]
     
    Benzotriazole (BTA) was added in a conducting Polypyrrole (PPy) film prepared on copper in oxalic acid aqueous solution containing pyrrole monomer to improve corrosion protection by the PPy film and reduce copper corrosion. When BTA was added in the preparation solution, the copper surface was covered by a BTA-Cu complex layer before the anodic polymerization of PPy was started. On the copper surface with the BTA layer, the initial dissolution of copper was inhibited and the PPy polymerization-deposition was started immediately after the anodic current was imposed. The PPy film thus formed was doped with oxalic ions and ionized BTA and was homogeneous in thickness and strongly adhesive. The PPy film containing BTA protected the copper from corrosion in 3.5 wt.% NaCl solution. In 400 h of immersion, copper dissolution was inhibited with 80% protection efficiency relative to that of bare copper. (C) 2013 Elsevier B.V. All rights reserved.
  • Mikito Ueda
    MOLTEN SALTS AND IONIC LIQUIDS 19 64 (4) 243 - 248 1938-5862 2014 [Refereed][Not invited]
     
    Electrochemical reactions of metallic sodium were investigated in NaTFSI-TEATFSI ionic liquids and NaTFSI-TBATFSI ionic liquids at 160 degrees C. The melting point of the ionic liquids was 36 degrees C with lowest value in 20 mol% NaTFSI-TEATFSI. The maximum value of electrical conductivity was 36 mScm(-1) at 20 mol% NaTFSI-TEATFSI from the impedance measurement. In the anodic polarization curves, a diffusion limit current was observed at -1.8 V vs. Pt(Q.R.E) at the ionic liquid. The electrorefining experiments for 30 h were carried out at 160 degrees C. After the electrorefining, metallic sodium of 99.99 % purity was obtained by the electrorefining.
  • Wataru Majima, Hisayoshi Matsushima, Yasuhiro Fukunaka, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 161 (10) F1002 - F1005 0013-4651 2014 [Refereed][Not invited]
     
    The dynamic behavior of the meniscus of a potassium hydroxide and sulfuric acid droplet on a platinum electrode was studied using a charge-coupled device (CCD) camera and confocal laser microscopy. The three-phase interface was investigated during the hydrogen oxidation reaction (HOR) and the hydrogen evolution reaction (HER). Contact angle measurements revealed a spreading interface during the HER whereas the droplet shape remained unchanged during the HOR for both droplets. The overhead view revealed the formation of many fine droplets near the meniscus boundary during the HOR in the alkaline electrolyte, which agrees with previous results for the oxygen reduction reaction (ORR). The correlation of these observations with electrochemical data and differences in the results between the HOR and the HER suggest that the motion of the meniscus was induced by local pH and temperature gradients, presumably caused by a non-uniform reaction because of the limitations of the dissolved gas. (c) 2014 The Electrochemical Society. All rights reserved.
  • YanHua Lei, Nan Sheng, Atsushi Hyono, Mikito Ueda, Toshiaki Ohtsuka
    Corrosion Science 76 302 - 309 0010-938X 2013/11 [Refereed][Not invited]
     
    Phytic acid (C6H18O24P6), the principal phosphorous storage form in many plant tissues, is a green material. A polypyrrole (PPy) doped with phytic acid (IP6) was electrosynthesised on copper from an aqueous phytic acid solution. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and SEM were used to characterise the polymer. The polymer-covered copper was subjected to a corrosion test in NaCl solution. The dissolution of copper covered with PPy-IP6 was found to be greatly inhibited in NaCl solution. The inhibition indicated protection of the PPy-IP6 layer against copper corrosion. © 2013 Elsevier Ltd.
  • Takahiro Mineta, Seiji Miura, Toshiji Mukai, Mikito Ueda, Tetsuo Mohri
    JOURNAL OF THE JAPAN INSTITUTE OF METALS AND MATERIALS 77 (10) 466 - 472 0021-4876 2013/10 [Refereed][Not invited]
     
    In Mg alloys, the most favorable deformation mechanism is the basal slip, and extension twinning also contributes to plastic deformation. Other mechanisms such as prismatic slips, pyramidal slips and twinning except for extension twinning scarcely occur. However, these slip systems also contribute to the plastic deformation of poly crystal Mg alloys, so the determination of CRSS of such non-basal slip systems are inevitable as a basis for the prediction of the deformation behavior of poly-crystal Mg alloys. Because of the difficulty of the evaluation of CRSS for non-basal slip by conventional compression test, newly designed "Pure shear test" is applied to evaluate the CRSS of the prismatic slip Mg alloy single crystals containing Y. Also a modification of Bridgman method using LiF + LiCl is attempted to obtain a pure-Mg single crystal.
  • Mikito Ueda, Hajime Matsunaga, Toshiaki Ohtsuka
    ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS 227 (8) 1097 - 1103 0942-9352 2013/09 [Refereed][Not invited]
     
    To develop an aluminum-chlorine cell, an electrochemical cell consisting of an aluminum anode and a graphite cathode was developed and evaluated in EMIC-AlCl3 ionic liquid. The open circuit voltage of the aluminum-chlorine cell was about 1.8-1.9 V after introduction of chlorine gas to 66.7 mol % EMIC-AlCl3 at 303 K. The relationship between current density and cell voltage in the cell showed an almost linear relation. The major factor in the voltage drop of the output voltage was considered to be due to resistance of electrolytic melt. The output characteristics of the cell depend on the configuration of the graphite cathode, the current density with a step type cathode at 0.5 V was about 20% better than that of a cylindrical type graphite cathode.
  • Mikito Ueda, Ryuichi Inaba, Toshiaki Ohtsuka
    Electrochimica Acta 100 281 - 284 0013-4686 2013/06/30 [Refereed][Not invited]
     
    To form Al-Sn alloys for bearing materials, molten salt electrolysis was performed in an AlCl3-NaCl-KCl molten salt containing SnCl 2 at 423 K. The voltammogram showed that the cathodic reduction of the Sn ions started at a potential of 0.5 V vs. Al/Al(III) in the molten salt showing that deposition of pure Sn was possible at 0.5 V. Co-deposition of Al and Sn occurred at potentials more negative than 0.1 V. The co-deposit was composed a solid solution of Al and Sn. The ratio of the Sn in the electrodeposits decreased with the potential from 100 at.% at 0.2 V to 19 at.% at -0.3 V. In the structural observations, electrodeposits with an alternate stacked structure of Al and Sn is obtained at -0.075 V. © 2012 Elsevier Ltd.
  • Mikito Ueda, Kazuya Honda, Toshiaki Ohtsuka
    ELECTROCHIMICA ACTA 100 265 - 268 0013-4686 2013/06 [Refereed][Not invited]
     
    To develop a electrorefining process of sodium for the recycling of used sodium-sulfur secondary battery, a non-aqueous electrolytic melt was investigated as a candidate for the process. A mixed ionic liquid of NaTFSI (sodium-bis(trifluoremethylsulfonyl)imide)-TEATFSI (tetraethylammonium-bis(trifluoremethylsulfonyl)imide) was selected for the electrolyte, since it has a wide potential window and a weak reactivity with metallic sodium. From AC impedance measurements, the maximum electric conductivity of 36 mS cm(-1) was found for a concentration of 20 mol% NaTFSI-TEATFSI at 433 K. The cathodic deposition of liquid sodium, 99.99% pure, was obtained on a glassy carbon electrode by constant current electrolysis. The calcium concentration in the sodium was decreased from 500 to 12 ppm by the electrorefining. A cathodic current efficiency at 88% was achieved in these electrorefining experiments. (C) 2012 Elsevier Ltd. All rights reserved.
  • Nan Sheng, Mikito Ueda, Toshiaki Ohtsuka
    Progress in Organic Coatings 76 (2-3) 328 - 334 0300-9440 2013/02 [Refereed][Not invited]
     
    The electropolymerization of conducting polypyrrole (PPy) film on zinc-coated AZ91D magnesium alloy under constant current control in aqueous sodium tartrate containing pyrrole monomer was investigated using Raman spectroscopy and surface observation. Zinc oxide and zinc hydroxide are initially formed, which are then replaced by a zinc tartrate salt layer. The PPy nucleation is initiated on the zinc layer covered by zinc tartrate, followed by three-dimensional growth of the PPy layer. © 2012 Elsevier B.V.
  • Mikito Ueda, Shizuka Hariyama, Toshiaki Ohtsuka
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 16 (11) 3423 - 3427 1432-8488 2012/11 [Refereed][Not invited]
     
    To improve the corrosion resistance of Mg alloys, an Al layer was electrodeposited on the Mg surface from an ionic liquid of 1-ethyl-3-methylimidazolium chloride (EMIC) and aluminum chloride (AlCl3) at 283 K. A smooth surfaced Al electrodeposit can be electroplated in the AlCl3-EMIC ionic liquid by pulse electrolysis at 6.7 Hz and a duty ratio of 0.67. A denser and flatter Al layer was successfully electroplated on AZ121 substrate at the lower temperature of 283 K in an AlCl3-EMIC ionic liquid with 0.1 M ethylene glycol added.
  • Mikito Ueda, Hajime Matsunaga, Toshiaki Ohtsuka, Toshiharu Yamashita
    MATERIALS TRANSACTIONS 53 (3) 575 - 577 1345-9678 2012/03 [Refereed][Not invited]
     
    To investigate the diffusion behavior of Tl ions, glass was immersed in TINO3-KNO3 molten salt at 753 K for various lengths of time. The Tl ions embedded in the glass were then reduced to metallic Tl nano-particles by hydrogen at 803 K for 1 h. The depth of the ion exchange layer down to about 140 mu m in the glass was found to be proportional to a square root of the length of immersion time. It was suggested that the ion exchange process is controlled by the diffusion of Tl ions from the surface to the inside. Reduction of Tl ions to metallic Tl with the hydrogen gas occurred only at the surface down to 4 mu m. The concentration profile of the metallic Tl is discussed by nucleation-nucleus growth and the diffusion of Tl ions from deeper areas. [doi:10.2320/matertrans.M2011343]
  • Electrodeposition of Al alloys as a lubricating material in molten salt
    Mikito Ueda
    4th Asian conference on Molten salt chemistry and technology 18 - 23 2012 [Not refereed][Invited]
  • Electrowinning of Li from LiOH by BDD anode and tungsten cathode
    Knichiro Yoshida, Mikito Ueda, Toshiaki Ohtsuka
    4th Asian conference on Molten salt chemistry and technology 394 - 395 2012 [Not refereed][Not invited]
  • Formation of Ag alloy particles in the glass by ion exchange treatment in molten salt
    Yuko Sakai, Mikito Ueda, Toshiaki Ohtsuka
    4th Asian conference on Molten salt chemistry and technology 364 - 365 2012 [Not refereed][Not invited]
  • Mikito Ueda, Hideki Hayashi, Toshiaki Ohtsuka
    SURFACE & COATINGS TECHNOLOGY 205 (19) 4401 - 4403 0257-8972 2011/06 [Refereed][Not invited]
     
    To form Al-Pt alloys for high temperature coatings, molten salt electrolysis was attempted with an AlCl3NaCl-KCl molten salt containing PtCl2 at 448 K. The voltammogram showed cathodic reduction of Pt ions to start at a potential of 1.4 vs. Al/Al(III) in the molten salt. Deposition of pure Pt was possible at 1.2 V and there was co-deposition of Al and Pt at potentials more negative than 1.0 V. The co-deposit was a mixture of intermetallic compounds of AlPt2 or AlPt3. The ratio of the Pt in the electrodeposits decreased with increasingly negative potentials from 100 at.% at 1.2 V to 25 at.% at 0.0 V. (C) 2011 Elsevier B.V. All rights reserved.
  • Evaluation of NaTFSI -TEATFSI ionic liquid as an electrolytic melt for Na electrorefining
    Mikito Ueda, Kazuya Honda, Toshiaki Ohtsuka
    Proc. Electrochemical Society, Molten Salt 2534  2011 [Not refereed][Not invited]
  • Electrodeposition of Al-Sn alloys in AlCl3-NaCl-KCl molten salt containing SnCl2
    Mikito Ueda, Ryuichi, Toshiaki Ohtsuka
    International Symposium on Renewable Energy and Materials Tailoring 19  2011 [Not refereed][Not invited]
  • Electrorefining reaction of Na in TEATFSA-NaTFSA ionic liquid
    Mikito Ueda, Kazuya Honda, Toshiaki Ohtsuka
    International Symposium on Renewable Energy and Materials Tailoring 2011 [Not refereed][Not invited]
  • Development of Al-Cl2 battery in EMIC-AlCl3 ionic liquid
    Hajime Matsunaga, Mikito Ueda, Toshiaki Ohtsuka
    62nd Annual Meeting of International Society of Electrochemistry 2011 [Not refereed][Not invited]
  • Electroplating temperature for Al plating on Mg alloy in AlCl3-EMIC ionic liquid
    Shizuka Hariyama, Mikito Ueda, Toshiaki Ohtsuka
    62nd Annual Meeting of International Society of Electrochemistry 2011 [Not refereed][Not invited]
  • Oxygen reduction of Pd electrodes covered by platinum monolayers
    Toshiaki Ohtsuka, Yoshikazu Sugawara, Mikito Ueda
    62nd Annual Meeting of International Society of Electrochemistry 2011 [Not refereed][Not invited]
  • In situ observation of heterogeneity on thin titanium passive oxide film by micro-ellipsometry
    Atsushi Hyono, Kenji Yamanaka, Mikito Ueda
    62nd Annual Meeting of International Society of Electrochemistry 2011 [Not refereed][Not invited]
  • Diffusion of Tl ion into the glass by ion exchange treatment
    Mikito Ueda, H Matsunaga, Toshiaki Ohtsuka
    9th International symposium on Molten salt 101 - 106 2011 [Not refereed][Not invited]
  • Electroplating of aluminum alloys for improving oxidation resistance of TiAl intermetallics
    Mikito Ueda
    Proceedings of International conference on functional nanocoatings 27 - 28 2010 [Not refereed][Not invited]
  • Mikito Ueda, Yasushi Tabei, Toshiaki Ohtsuka
    MOLTEN SALTS AND IONIC LIQUIDS 17 33 (7) 563 - 570 1938-5862 2010 [Not refereed][Not invited]
     
    In order to improve the corrosion resistance of Mg and its alloys, Al layer was electrodeposited on their surface from aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Mirror-like Al surface can be electroplated in AlCl3-EMIC ionic liquid by pulse electrolysis at 323 K, though Al layer was not dense and homogeneous. A dense and flat Al layer was successfully electroplated on Mg alloys in the AlCl3-EMIC ionic liquid at lower temperature of 283 K.
  • Formation of Nano-Particle in a Glass by Ion-Exchange Treatment
    Mikito Ueda, Yasushi Tabei, Toshiaki Ohtsuka, Toshiharu Yamashita
    The 12th International Symposium on Biomimetic Materials Processing 62  2010 [Not refereed][Not invited]
  • Mikito Ueda, Yasushi Tabei, Toshiaki Ohtsuka
    MOLTEN SALTS AND IONIC LIQUIDS 17 33 (7) 563 - 570 1938-5862 2010 [Not refereed][Not invited]
     
    In order to improve the corrosion resistance of Mg and its alloys, Al layer was electrodeposited on their surface from aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Mirror-like Al surface can be electroplated in AlCl3-EMIC ionic liquid by pulse electrolysis at 323 K, though Al layer was not dense and homogeneous. A dense and flat Al layer was successfully electroplated on Mg alloys in the AlCl3-EMIC ionic liquid at lower temperature of 283 K.
  • KIKUCHI Tatsuya, SHIMAGUCHI Hiroko, UEDA Mikito, SAKAIRI Masatoshi, YONEZAWA Tetsu, TAKAHASHI Hideaki
    Jitsumu Hyomen Gijutsu 表面技術協会 61 (9) 652 - 657 0915-1869 2010 [Not refereed][Not invited]
     
    A printing plate for gravure printing consisting of five layers of aluminum alloy / anodic oxide film / nickel / polypyrrole / copper was fabricated by anodizing, electro-less plating, electroplating, and electro-polymerization. Nickel layers were first deposited on anodic oxide film-covered aluminum alloy by electro-less plating and electroplating. The polypyrrole layer was then deposited on the nickel layer by anodic polarization in a pyrrole monomer solution. Many copper fine particles were deposited on the polypyrrole-deposited specimen at the initial stage of electroplating in the CuSO4 / H2SO4 solution; then a continuous copper layer was obtained through longer cathodic polarization. The copper layer with polypyrrole was removed easily from the nickel layer by pulling with adhesive tape, which suggests that the structure is useful as a reusable aluminum printing plate by copper electroplating and electro-polymerization.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    JOURNAL OF MATERIALS CHEMISTRY 20 (36) 7630 - 7633 0959-9428 2010 [Refereed][Not invited]
     
    The present work demonstrates a new approach to self-healing polymers that have the ability to repair artificial defects and restore the passive state of an underlying metal substrate. An intrinsically conducting polymer (ICP) with a well designed function of doped ions possesses specific permselective properties, restricting incorporation of aggressive chlorides from corrosive electrolyte. The cation permselective membrane controls the release of healing ions to the defect zone when artificial defects are formed, efficiently inhibiting corrosion of the underlying metal substrate.
  • Mikito Ueda, Yasutaka Ta, Toshiaki Ohtsuka, Hidenori Takahashi
    JOURNAL OF THE JAPAN INSTITUTE OF METALS 日本金属学会 73 (10) 773 - 777 0021-4876 2009/10 [Not refereed][Not invited]
     
    To reduce Mg content in Al-Mg alloy for aluminum recycling, calcined powder made from used dry-cell battery was reacted with the liquid aluminum alloy. The powder was found to consist of ZnMn2O4, MnO, ZnO, and carbon by XRD analysis. After the reaction between pellets of the powder and the alloy in liquid at 973 K or 1073 K for 3.6 x 10(3) s, Mg content in the alloy decreased from 4.0 to 2.3 mass%. And at the same time, contents of Mn and Zn in the alloy increased from 0 to about 0.2 and 0.1 mass%, respectively. During the reaction, metallic Mg in the liquid Al-Mg alloy was found to move in to the pellets to form MgO. It may be assumed that an exchange reaction between Zn2+ at ZnO in the pellets and Mg2+ from the liquid alloy takes place.
  • Mikito Ueda, Hideki Hayashi, Toshiaki Ohtsuka
    JOURNAL OF THE JAPAN INSTITUTE OF METALS 日本金属学会 73 (9) 691 - 694 0021-4876 2009/09 [Not refereed][Not invited]
     
    To develop a sodium electrorefining process for the recycling of used sodium-sulfur secondary battery, a non-aqueous electrolytic melt was investigated to pursue an efficient solvent and electrolyte for the process. Propylene carbonate containing NaPF6 was selected, since it has a wide potential window for electrochemical stability and a weak reactivity with metallic sodium. From the impedance measurement of propylene carbonate containing NaPF6, the maximum electric conductivity of 75 mS cm(-1) was found at concentration of 1 M NaPF6 at 338 K. The cathodic deposition of metallic sodium on a glassy carbon electrode and the anodic dissolution of metallic sodium occurred in the electrolytic melt. Sodium and a small amount of phosphorus were detected in the electrodeposit by ICP-AES analysis.
  • Yasushi Tabei, Mikito Ueda, Toshiaki Ohtsuka, Toshiharu Yamashita
    ELECTROCHEMISTRY 77 (8) 709 - 712 1344-3542 2009/08 [Not refereed][Not invited]
     
    To make functional glasses, ion-exchange treatment of the glass surface was carried out in TlNO3-NaNO3 molten salt at 673 K and 723 K for various time periods, and then the Tl ions embedded in the glass were reduced to metallic Tl nanoparticles by hydrogen gas. The color of the glass containing metallic Tl nanoparticles changed to brown or black. The Tl nanoparticles were detected by a qualitative TEM analysis. The optical absorption spectra of these treated glasses showed a peak at about 370 nm. With increases in the temperature of the molten salt, the band intensity of the absorption is enhanced. The absorption increase may correspond to larger particle sizes and densities with the increase in temperature. The Tl nanoparticles with 10-150 run diameter were observed at neighboring parts of the glass surface by TEM and FE-SEM.
  • Mikito Ueda, Shoh Tsuchiya, Toshiaki Ohtsuka
    ELECTROCHEMISTRY 77 (8) 659 - 662 1344-3542 2009/08 [Not refereed][Not invited]
     
    The electrodeposition of Sb-Bi-Te alloy in AlCl3-NaCl-KCl molten salt containing SbCl3, BiCl3, and TeCl4, at 423 K was carried out under constant potential control and potential pulse control in the melt. The electrodeposition results show that the SbCl3 concentration is effective to control the composition of Bi-Sb-Te ternary alloy. The electrodeposited Bi0.5Sb1.5Te3 by pulse electrolysis with frequency = 100 Hz and D. R. (Duty Ratio)= 75%, had good crystallinity and the preferential orientation of the electrodeposit was the (110) plane in this electrodeposition experiments. The electrodeposit had homogeneous disk-like granules. The power factor of the electrodeposit was calculated as 3 x 10(-5) Wm(-1) K-2 from the Seebeck coefficient and the electrical conductivity.
  • UEDA Mikito, UI Koichi
    Journal of The Surface Finishing Society of Japan 一般社団法人 表面技術協会 60 (8) 491 - 496 0915-1869 2009/08 [Not refereed][Invited]
  • Yuichi Tamura, Kento Taneda, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 51 (7) 1560 - 1564 0010-938X 2009/07 [Not refereed][Not invited]
     
    Effect of surface oxide on Pt-Co alloy electrodes on the oxygen reduction reaction (ORR) was investigated in 0.5 M sulfuric acid Solution by electrochemistry, ellipsometry. laser Raman scattering spectroscopy, and XPS. The oxide as thick as 1-2 nm increases the overpotential of ORR and falls down efficiency of PEFC. The thickness of the oxide films is precisely determined by ellipsometry. The oxide film 1.9 nm thick was formed on Pt-50 mol% Co electrode by constant potential oxidation at 1.20 V and the film 1.5 nm thick remains on the electrode at 0.6 V at which ORR already starts. The remaining oxide decreases the current density of ORR and increases the overpotential. On pure Pt electrode, the similar influence of the oxide filrn was observed. (C) 2008 Elsevier Ltd. All rights reserved.
  • Yusuke Mito, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 51 (7) 1540 - 1544 0010-938X 2009/07 [Not refereed][Not invited]
     
    Photo-luminescence emission was measured from the thin passive oxide him on nickel and chromium under the in-situ condition in 0.1 kmol m(-3) (M) sulfuric acid solution at pH 0.9 and neutral buffer solution of borate-boric acid mixture at pH 8.4 in order to obtain the insight of the electronic properties in the passive oxide film as thin as a few nm. The photo-luminescence induced by UV laser beam at 325 nm wavelength from nickel oxidized in both pH 0.9 sulfuric acid and pH 8.4 borate buffer solutions exhibited a broad spectrum feature with a peak at 400-420 nm. The energy of the peak wavelength from 400 to 420 nm is 2.95-3.10 eV which may correspond to the band-gap energy of the semiconduncting NiO. The photo-luminescence spectra from chromium oxidized in the sulfuric acid and neutral borate solutions had a peak at 400 nm and about 440 nm, respectively. These photo-emission from nickel and chromium oxidized is assumed to correspond to luminescence accompanied by recombination between excess electrons produced by UV light illumination in the conduction band and positive holes in the valence band. The broad tailing of the luminescence at longer wavelength side may represent high density of localized states originated in an amorphous nature of the passive oxides. (C) 2008 Elsevier Ltd. All rights reserved.
  • KIKUCHI Tatsuya, UEDA Shingo, UEDA Mikito, SAKAIRI Masatoshi, TAKAHASHI Hideaki
    Journal of The Surface Finishing Society of Japan 表面技術協会 60 (5) 335 - 341 0915-1869 2009/05/01 [Not refereed][Not invited]
     
    Three-dimensional micro-actuators consisting of a polypyrrole (PPy)/Au bi-layer, were fabricated by Al anodizing, laser irradiation, and electrochemical techniques. Aluminum specimens covered with porous type oxide films were irradiated with a pulsed Nd-YAG laser to remove the oxide films locally. Then an Au layer and a PPy layer were deposited at the area where the film had been removed. Finally, the specimens were immersed in a NaOH solution after connection with or without a Pt plate to separate PPy/Au actuators from the Al substrate and anodic oxide film. The PPy layer did not lose its ...
  • Na electrodeposition in propylene carbonate containing NaPF6, Proc. Electrochemical Society
    Mikito Ueda, Hideki Hayashi, Toshiaki Ohtsuka
    Organic electrochemistry 09 - 10 2009 [Not refereed][Not invited]
  • Mikito Ueda, Yusuke Mito, Toshiaki Ohtsuka
    MATERIALS TRANSACTIONS 49 (8) 1720 - 1722 1345-9678 2008/08 [Not refereed][Not invited]
     
    The Electrodeposition of Sb-Te alloy was carried Out in AlCl3-NaCl-KCl molten salt containing SbCl3 and TeCl4 at 423 K by constant potential electrolysis. The voltammogram on a glassy carbon (GC) electrode in a melt containing 1.0 X 10(-2) kmol m(-3) SbCl3 and 1.0 X 10(-2) kmol/m(3) TeCl4 revealed the cathodic current waves at 1.5, 1.1, and 0.9 V vs. Al/Al(III). A stable Sb-Te alloy deposit was obtained at 0.85 V in the melt containing SbCl3 and TeCl4. At the higher concentration ratio of the Sb(III) to (Sb(III) + Te(IV)). a good linear relation was found between the atomic ratio of Sb in the deposit and the concentration ratio of Sb (III) in the melt. The Sb-Te alloy deposit of atomic ratio of 38 : 62% which was assume to be suitable for a thermoelectric device was obtained with the molten salt containing 7.0 x 10(-3) kmol/m(3) SbCl3 and 1.0 x 10(-2) kmol/m(3) TeCl4. The XRD pattern of the deposit corresponds to that of Sb2Te3 intermetallic compound. The deposit had homogeneous disk-like granule with the disk size of about 10 mu m..
  • Mikito Ueda, Yusuke Mito, Toshiaki Ohtsuka
    MATERIALS TRANSACTIONS 49 (8) 1720 - 1722 1345-9678 2008/08 [Not refereed][Not invited]
     
    The Electrodeposition of Sb-Te alloy was carried Out in AlCl3-NaCl-KCl molten salt containing SbCl3 and TeCl4 at 423 K by constant potential electrolysis. The voltammogram on a glassy carbon (GC) electrode in a melt containing 1.0 X 10(-2) kmol m(-3) SbCl3 and 1.0 X 10(-2) kmol/m(3) TeCl4 revealed the cathodic current waves at 1.5, 1.1, and 0.9 V vs. Al/Al(III). A stable Sb-Te alloy deposit was obtained at 0.85 V in the melt containing SbCl3 and TeCl4. At the higher concentration ratio of the Sb(III) to (Sb(III) + Te(IV)). a good linear relation was found between the atomic ratio of Sb in the deposit and the concentration ratio of Sb (III) in the melt. The Sb-Te alloy deposit of atomic ratio of 38 : 62% which was assume to be suitable for a thermoelectric device was obtained with the molten salt containing 7.0 x 10(-3) kmol/m(3) SbCl3 and 1.0 x 10(-2) kmol/m(3) TeCl4. The XRD pattern of the deposit corresponds to that of Sb2Te3 intermetallic compound. The deposit had homogeneous disk-like granule with the disk size of about 10 mu m..
  • Electrodeposition of Bi-Sb-Te alloys in molten salt
    Mikito Ueda, Syou Tstushiya, Toshiaki Ohtsuka
    8th International Symposium on Molten Salts 445 - 450 2008 [Not refereed][Not invited]
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 50 (1) 286 - 291 0010-938X 2008/01 [Not refereed][Not invited]
     
    Ultrasonic irradiation was imposed during electropolymerization of polypyrrole (PPy) in acid phosphate solution containing molyb-dophosphate (PMo12O403-) ions and pyrrole monomer. Corrosion of the steel coated by the PPy film prepared under ultrasonic irradiation was tested in 3.5 wt.% NaCl solution and compared with corrosion of the steel coated by the PPy film without ultrasonic irradiation. The PPy film prepared under ultrasonic irradiation kept the steel in the passive state one and a half times as long as that prepared without ultrasonic irradiation. Imposition of ultrasound enhanced the doping of PMo12O403-. and decreased the doping of HPO42-. The surface morphology of the PPy film was changed with imposition of ultrasound in electropolymerization process. Under imposition of ultrasound, a dense and compact PPy layer was formed. The structure of the PPy film obtained under ultrasonic irradiation was assumed to result from change in nucleation-growth mechanism. (c) 2007 Elsevier Ltd. All rights reserved.
  • M. Ueda, T. Ohtsuka, K. Kuroda, R. Ichino, M. Okido
    TRANSACTIONS OF THE MATERIALS RESEARCH SOCIETY OF JAPAN, VOL 33, NO 3 33 (3) 779 - 782 2008 [Not refereed][Not invited]
     
    For application of Ti to the bio-implant materials, the anodic etching of Ti in the molten salt of LiCl-KCl and EMIC-AlCl(3) was investigated. The roughness of the Ti surface after the etching was examined from the SEM observation. The etching of the Ti electrode in the melt of LiCl-KCl did not form a Suitably rough Surface morphology. In the melt, the largely rough surface was formed with top-to-bottom distance of 10 mu m. The etching in the melt of EMCI-AlCl(3) at the potential of 0.6 V vs. Al/Al(III) introduced the formation of a rough Surface applicable to the Ti implant. The rough surface formed in the melt exhibits the top-to bottom distance of about 1 mu m.
  • Y. Tamura, K. Taneda, M. Ueda, T. Ohtsuka
    PROTON EXCHANGE MEMBRANE FUEL CELLS 8, PTS 1 AND 2 16 (2) 741 - 750 1938-5862 2008 [Not refereed][Not invited]
     
    PtCo and PdCo alloy electrodes were investigated in a 0.5 M sulfuric acid solution by electrochemistry, ellipsometry, laser Raman scattering spectroscopy, XPS, and GD-OES. The corrosion resistibility of Pt-Co and Pd-Co alloys decreased with increase of Co addition. The increase of Co addition, however, enhanced the catalytic efficiency on the ORR. The alloy surfaces may be covered by CoOOH and Pt or Pd oxide 2-3nm thick. At the potential of 1.2V vs. Ag/ AgCl/ sat. KCl, the thickness of oxide film increased with the Co addition. The presence of the oxide film on the alloy electrodes increases the overvoltage for the ORR. The effect of the oxide thickness on the ORR was discussed.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    ECS Transactions 16 (52) 177 - 182 1938-5862 2008 [Not refereed][Not invited]
     
    A bi-layered PPy film consisting of an inner layer doped with Keggin-structure anions of PMo12O403- and HPO42- (PPy-PMo12) and an outer layer doped with organic anions of dodecyl sulfate (PPy-DoS) exhibited a self-healing property when coated on steel. When a defect was introduced into the PPy-coated steel immersed in 3.5% NaCl aqueous solution, the potential initially decreased and activation of the coated steel occurred. After a few hours, the potential was recovered to the passive region, and the passivation continued for another 20 hours. Without any damage, the release of PMo12 doped in the inner layer was inhibited by the outer PPy layer doped with DoS. When a defect was introduced into the PPy film, the inner PPy layer released phosphate and molybdate anions to the damaged zone due to their decomposition via hydrolysis. Both anions work as passivation inhibitors and helped to repassivate the damaged zone on the steel. ©The Electrochemical Society.
  • Hirofumi Ebe, Mikito Ueda, Toshiaki Ohtsuka
    ELECTROCHIMICA ACTA 53 (1) 100 - 105 0013-4686 2007/11 [Not refereed][Not invited]
     
    The Electrochemistry of Sb, Bi, and Te in AlCl3-NaCl-KCl molten salt containing SbCl3, BiCl3, and/or TeCl4 at 423 K was investigated by voltammetry, and electrodeposition of the three metals was performed under constant potential control in the melt. The voltammogram on a glassy carbon (GC) electrode in a melt containing 0.025 mol dm(-3) [M] SbCl3 showed a couple of redox peak corresponding to the Sb/Sb(III) redox reaction, and a stable layer of pure Sb was deposited under the constant potential control. The voltammograms in the melt containing 0.025 M BiCl3 or 0.025 M TeCl4 showed several redox couples. Stable deposit layers of pure Bi and Te were not obtained under the constant potential control, as the deposited layers detached from the electrode and immediately dissolved into the molten salt. Binary alloy deposition was possible in a melt containing BiCl3 and SbCl3, and also with BiCl3 and TeCl4. A stable Bi-Sb alloy deposit of metallic Sb and Bi-Sb solid solution was obtained at 0.8 and 0.9 V versus Al/Al(III) in the melt containing BiCl3 and SbCl3. The atomic ratio of Bi in the deposit was 37% at 0.9 V and 57% at 0.8 V. A stable Bi-Te alloy deposit was also obtained with the molten salt containing BiCl3 and TeCl4. The deposited Bi-Te alloy consisted of a mixture of Bi2Te3, BiTe, and Bi2Te. The alloy deposit had good crystallinity and the preferential orientation was the (I 10) plane. (C) 2007 Elsevier Ltd. All rights reserved.
  • Mikito Ueda, Haku Ryu, Toshiaki Ohstuka, Hidenori Takahashi
    JOURNAL OF THE JAPAN INSTITUTE OF METALS 日本金属学会 71 (11) 1046 - 1049 0021-4876 2007/11 [Not refereed][Not invited]
     
    A composite oxide produced from used dry battery was used to decrease Mg content in Al-Alg alloy at high temperature. The oxide was found to consist of ZnMn2O4, ZnMnO3, and ZnO by XRD analysis. After a reaction between a pellet made from the oxide powder and the alloy in liquid at 973 K for 2 h, Mg content in the alloy decreased from 4.0 to 3.6 mass%. During the reaction, metallic Mg probably diffused into the pellet to form MgMn2O4 and then exchanged with Zn(II) in ZnMn2O4.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 49 (8) 3442 - 3452 0010-938X 2007/08 [Not refereed][Not invited]
     
    The bi-layered polypyrrole (PPy) coatings were investigated for corrosion prevention of a carbon F steel. The inner layer was doped with the Keggin structure anions Of PMO12O403- (PMO12) and HpO(4)(2-) anions for stabilization of the passive oxide film at the metal-polymer interface, and the outer layer was doped with four organic anions of dihydroxynaphthalenedisulfonate (DHNDS), naphthalenedisulfonate (NDS), anthraquinonedisulfonate (AnqDS) or dodecylsulfate (DoS) for inhibition of the decomposition and release of PMo12. The corrosion tests were performed in 3.5 wt.% NaCl aqueous solution. The corrosion resistance of the steels covered by the bi-layered PPy films was found in the following order: PPY-PMo12/PPy-DHNDS < PPY-PMo12/PPy-NDS < PPY-PMo12/AnqDS < Ilk PPY-PMO12/PPy-DoS. The performance of corrosion protection related to the oxidized state of the polymer was discussed. (c) 2007 Elsevier Ltd. All rights reserved.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 49 (3) 1635 - 1644 0010-938X 2007/03 [Not refereed][Not invited]
     
    Bi-layered polypyrrole (PPy) coating was investigated for corrosion prevention of steels. The PPy coating consisted of the inner layer doped with PMo12 40 (PMo12) and HPO42- ions and the outer layer doped with naphthalenedisulfonate (NDS) ions. PMo12 ions doped in the inner layer make the passive oxide film on steel stabilized and the outer layer doped with large organic ions of NDS restricts decomposition and release of PMo12 ions in the inner layer. Corrosion tests were made in 3.5% NaCl aqueous solution for the steels covered by the single PPy-PMo12, single PPy-NDS, and bi-layered PPy-PMo12/PPy-NDS coatings. The single PPy-PMo12 and PPy-NDS coatings maintained the steel in passive state for 34h and 24h, respectively. The bi-layered coating kept the steel in passive state and prevented corrosion of the steels for the longer time period. (c) 2006 Elsevier Ltd. All rights reserved.
  • T. Kikuchi, Y. Akiyama, A. Ueda, A. Sakairi, H. Takahashi
    ELECTROCHIMICA ACTA 52 (13) 4480 - 4486 0013-4686 2007/03 [Not refereed][Not invited]
     
    Ribbon type and three-dimensional micro-actuators, consisting of three-layer structure of acrylic acid resin/Au/polypyrrole, were fabricated by aluminum anodizing, laser irradiation, and electrochemical techniques, and their performance was examined. Anodized aluminum specimens were irradiated with a pulsed Nd-YAG laser to remove anodic oxide films locally, and then an An layer was deposited at the area where film had been removed. The subsequent electrophoretic deposition of acrylic acid resin on the An layer, dissolution of anodic oxide film and the metal substrate, and deposition of polypyrrole on backside of An layer by electro-polymerization enabled the fabrication of a three-layer actuator. Cyclic voltammetry of the ribbon type actuator in different electrolyte solutions showed that redox reactions of polypyrrole is accompanied with doping and dedoping of hydrated cations, and that the redox reaction strongly depends on the valency of cations in the solutions. The three-dimensional micro-actuator showed good performance as a manipulator, gripping and moving objects of several milligram in solutions. (c) 2007 Elsevier Ltd. All rights reserved.
  • Mikito Ueda, Hirokuni Kigawa, Toshiaki Ohtsuka
    ELECTROCHIMICA ACTA 52 (7) 2515 - 2519 0013-4686 2007/02 [Not refereed][Not invited]
     
    To improve the oxidation resistance of TiAl intermetallic compound under high temperature condition, cathodic co-deposition of Al-Cr and Al-Ni alloy was carried out by constant potential control or potential pulse control in AlCl3-NaCl-KCl molten salt containing CrCl2 and/or NiCl2 at 423 K. Cathodic reduction of Ni and Cr starts at potential of 0.8 and 0.15 V versus Al/Al3+ in the molten salt, respectively. The co-deposition of At, Cr, and Ni occurred at potentials more negative than -0.1 V to form a mixture of intermetallic compounds of Cr2Al, Ni3Al, and Al3Ni. Concentration of Cr in the deposit was enhanced to 43 at% at -0.1 V; however, concentration of Ni in the deposit was 6 at% at the same potential. The concentration of Ni further decreased with more negative potential to 1 at% at -0.4 V. The potential pulse technique enhanced the Ni concentration in the deposit to about 30 at%, due to anodic dissolution of Al content from the deposit at the higher side of potential on the potential pulse electrolysis. (c) 2006 Elsevier Ltd. All rights reserved.
  • Silvio Koehler, Mikito Ueda, Igor Efimov, Andreas Bund
    ELECTROCHIMICA ACTA 52 (9) 3040 - 3046 0013-4686 2007/02 [Not refereed][Not invited]
     
    The potentiostatic deposition of polypyrrole (PPy) from 0.1 M aqueous phosphoric acid solution and the doping/dedoping behavior of the resulting films have been investigated by the electrochemical quartz crystal microbalance (EQCM) technique. The change of the complex shear modulus during the film growth and during the doping/dedoping were calculated using the acoustic impedance method. It was found that the films contain only ca. 1 wt% water in the oxidized state which is in accordance with their relatively high storage modulus of 38 MPa and low loss tangent of 0.05. Comparing H3PO4 (pH 1) and NaH2PO4 (pH 8) it was found that the doping/dedoping in the latter is accompanied by a strong increase of the surface roughness which is a direct result of cation exchange present at pH 8. (c) 2006 Elsevier Ltd. All rights reserved.
  • Anodic Dissolution of Ti in EMIC-AlCl3 Ionic Liquid or LiCl-KCl Molten Salt for Enhancement of Adhesion Between Coating Layer and Ti Substrate
    Mikito Ueda, Toshiaki Ohtsuka, Kensuke Kuroda, Ryoichi Ichino, Masazumi Okido
    Biodegradability and toxicity of ionic liquids meeting 16  2007 [Not refereed][Not invited]
  • Sho Tsuchiya, Mikito Ueda, Toshiaki Ohtsuka
    ISIJ INTERNATIONAL 47 (1) 151 - 156 0915-1559 2007 [Not refereed][Not invited]
     
    The polypyrrole (PPy) coating was prepared by constant current oxidation on zinc from aqueous solution of sodium tartrate containing sodium molybdate and pyrrole monomer to make new coating for corrosion prevention of zinc-coated steels. The coating is started with an initial formation of salt layer of zinc tartrate and/nor zinc molybdate during the oxidation. Nucleation and growth of PPy take place on the salt layer in the second stage. The PPy layer thus formed is doped by tartrate ions and/nor molybdate ions, which was confirmed by a depth profile measurement of glow discharge optical emission spectroscopy (GD-OES). The conductance of the coatings was as small as 1 x 10(-3) S cm(-2) for the 5 mu m-thick layer probably due to the formation of the salt layer underneath the PPy layer. Corrosion test of the PPy-coated zinc electrode in 3.5wt% NaCl solution showed that the zinc electrode was passivated and protected over 48 h by action of the oxidative PPy coating doped by tartrate and molybdate ions.
  • H. Hosoya, M. Arita, K. Hamada, Y. Takahashi, K. Higashi, K. Oda, M. Ueda
    JOURNAL OF PHYSICS D-APPLIED PHYSICS 39 (24) 5103 - 5108 0022-3727 2006/12 [Not refereed][Not invited]
     
    We investigate composite Fe-SrF2 films to explore new materials showing the granular-type tunnelling magnetoresistance (TMR) effect. The films are composed of Fe nano-particles embedded in a SrF2 matrix. The electromagnetic properties of the ferromagnetic metal-insulator films are confirmed, including super-paramagnetism, tunnel conduction and TMR. We obtain a TMR of 3% at RT and 5% at 77 K. The film resistivity is much higher than that of oxide-based granular film. We also fabricate the nanostructures of granular films and aim at the application of the single-electron transistor. As a result, we observed a Coulomb blockade (CB) region and CB oscillation at low temperature.
  • T Ohtsuka, M Iida, M Ueda
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 10 (9) 714 - 720 1432-8488 2006/09 [Not refereed][Not invited]
     
    The polypyrrole coating was prepared from phosphoric acid aqueous solution containing the hetero-polyanion PMo12O403- and pyrrole monomer to make new coating for corrosion prevention of carbon steels. The coating thus formed in the phosphate acid solution was doped by PMo12O403- and by PO43-. The coating was flexible enough to cover the steel homogeneously without cracks, although many cracks were observed on the coating formed in a neutral aqueous solution of Na2MoO2. The 5.1-mu m-thick polypyrrole coating makes the steel maintain the passive state for 48 h in neutral 3.5 wt% NaCl solution at pH 5.3 and for 80 h in acidic 3.5 wt% NaCl solution at pH 1.9. The coating decreased the corrosion rate of the steel by 1/200 in the neutral NaCl solution and by 1/340 in the acidic NaCl solution, if compared with the rate of the bare steel. The dissolution current of the steel during the immersion remained at the level of the typical passive current in the respective solutions.
  • Y Akiyama, T Kikuchi, M Ueda, M Iida, M Sakairi, H Takahashi
    ELECTROCHIMICA ACTA 51 (23) 4834 - 4840 0013-4686 2006/06 [Not refereed][Not invited]
     
    Polypyrrole was deposited at selected areas on aluminum by anodizing, laser irradiation, and electrolytic polymerization, and the application of the technique for fabricating micro-actuators was attempted. Aluminum specimens covered with porous type anodic oxide films were irradiated with a pulsed Nd-YAG laser to remove the oxide films locally, and then thin Ni layers were deposited at areas where film had been removed. Polypyrrole could be successfully deposited only on the Ni layer by anodic polarization of the specimens in pyrrole monomer solution, and a polypyrrole/Ni bilayer structure could be obtained by dissolution of the aluminum substrate and anodic oxide film in NaOH solutions. The bilayer structure was found to be inactive to doping and dedoping of ions during anodic and cathodic polarization. A three-layer structure, nitrocellulose/Ni/polypyrrole, fabricated by electrolytic polymerization after nitrocellulose coating on a Ni layer detached from the aluminum substrate, showed ion-doping and -dedoping activity, suggesting the possibility of fabricating micro-actuators in this manner. (c) 2006 Elsevier Ltd. All rights reserved.
  • M Ueda, Y Abe, T Ohtsuka
    MATERIALS LETTERS 60 (5) 635 - 638 0167-577X 2006/03 [Not refereed][Not invited]
     
    Direct reduction from SiO2 to metallic Si by aluminum metal fog was attempted in NaCl-KCl molten salt. The aluminum metal fog was evolved by contact of liquid aluminum metal to Al(III) in the molten salt. The metal fog forms in the molten salt an atmosphere reductive enough to induce a reaction from SiO2 to Si. The immersion of SiO2 plate at the aluminum metal fog in the molten salt caused the color change of the plate, and the plate exhibited the darker color with time. From EPMA and XRD analysis, metallic crystallized Si was detected in the darkened area. From the color change with time, the reaction proceeding was discussed. (c) 2005 Elsevier B.V. All rights reserved.
  • Co-deposition of Al-Cr-Ni Alloys Using Constant Potential and Potential Pulse Technique in AlCl3-NaCl-KCl Molten Salt
    Mikito Ueda, Hirokuni Kigawa, Toshiaki Ohtsuka
    4th Spring Meeting of International Society of Electrochemistry 20 - 21 2006 [Not refereed][Invited]
  • M Ueda, S Tsukamoto, S Konda, T Ohtsuka
    JOURNAL OF APPLIED ELECTROCHEMISTRY 35 (9) 925 - 930 0021-891X 2005/09 [Not refereed][Not invited]
     
    To recover aluminum from aluminum dross, a floating separation of aluminum alloy from the oxides and subsequent electrolysis of the oxides was carried out in a molten salt bath of 33 mol% AlF3, 51 mol% NaF and 16 mol% BaCl2. With A356.0 casting alloy dross, 83% of the aluminum alloy was recovered by the floating separation. A further 4% of metallic aluminum was recovered by electrolysis in the molten salt containing the oxides separated from the dross. The optimum current for continuous operation is discussed considering a balance between the electrowinning and dissolution rates.
  • M Ueda, H Ebe, T Ohtsuka
    ELECTROCHEMISTRY 73 (8) 739 - 741 1344-3542 2005/08 [Not refereed][Not invited]
     
    To improve the oxidation resistance of TiAl intermetallic compounds under high temperature conditions, electrodeposition of an Al, Cr, and Ni layer was carried out by constant potential control or potential pulse control in AlCl3-EMIC (1-ethyl-3-methyl-imidazolium chloride) ambient-temperature molten salt containing NiCl2 and CrCl2 at 338 K. The electrodeposition of Al, Cr, and Ni occurred at potentials lower than 0.0 V vs. Al/Al3+. Ni concentration in the deposit was about 9 at% at 0 V. However, it decreased with a decrease in potential to 1 at% at -0.2 V. The potential pulse technique enhanced the Ni concentration in the deposit to 20-27 at%. Cr concentration was also enhanced by pulse potential control: the concentration of Cr was raised to 15 at%. In all electrodeposits, sharp peaks corresponding to Al metal were detected with a relatively high background by XRD, analysis. It is conceivable that deposit layers consisting of Al, Cr, and Ni may be amorphous.
  • T Sato, M Ueda, Saeki, I
    ELECTROCHEMISTRY 電気化学会 73 (8) 736 - 738 1344-3542 2005/08 [Not refereed][Not invited]
     
    Limiting current densities of silver deposition in AlCl3-NaCl-AgCl or LiCl-KCl-AgCl melts, and change in the equilibrium potential of silver with AlCl3 concentration were measured to consider a large potential difference in the two melts. Diffusion rate of silver species in AlCl3-NaCl-AgCl melt was concluded to be much slower than that in LiCl-KCl-AgCl melt. The formation of a silver complex in AICl(3)-NaCI-AgCl melt was suggested. The equation, Ag + AlCl4- = AgAlCl4 + e or Ag + 2 AlCl4- =Ag(AlCl4)(2-) + e., might be a possible electrochemical reaction of silver in the melt.
  • Reduction of SiO2 to Si by Aluminum particles in NaCl-KCl-AlCl3 Molten Salt
    Mikito Ueda, Yoshihisa Abe, Toshiaki Ohtsuka
    7th International Symposium on Molten Salt 247 - 249 2005 [Not refereed][Not invited]
  • Co-deposition of Al-Cr-Ni alloy using a pulse electrolysis in AlCl3-EMIC molten salt
    Mikito Ueda, Hirofumi Ebe, Toshiaki Ohtsuka
    1st congress of international ionic liquid 121 - 122 2005 [Not refereed][Not invited]
  • Atmospheric Corrosion of Zinc and Zinc Alloy Using In-situ Raman Spectroscopy
    Mikito Ueda, Masaru Matsuda, Toshiaki Ohtsuka
    Proc. Electrochemical Society meeting, Atmospheric corrosion 215 - 219 2004 [Not refereed][Not invited]
  • Co-deposition of Al-Cr and Al-Ni Alloys Using Potential Pulse Technique in Molten Salt
    Mikito Ueda, Hirokuni Kigawa, Toshiaki Ohtsuka
    The 14th International Symposium on Molten Salt 2459  2004 [Not refereed][Not invited]
  • Atmospheric Corrosion of Zinc and Zinc Alloy Using In-situ Raman Spectroscopy
    Mikito Ueda, Masaru Matsuda, Toshiaki Ohtsuka
    Proc. Electrochem. Soc. Meeting 765  2004 [Not refereed][Not invited]
  • Corrosion Products on Zinc-coated Steels Detected by in-situ Raman Spectroscopy
    Mikito Ueda, Masaru Matsuda, Toshiaki Ohtsuka
    Galvatech ’04 Conference Proceedings 845 - 852 2004 [Not refereed][Not invited]
  • M Ueda, D Susukida, S Konda, T Ohtsuka
    SURFACE & COATINGS TECHNOLOGY 176 (2) 202 - 208 0257-8972 2004/01 [Not refereed][Not invited]
     
    For improvement of the oxidation resistance of a TiAl alloy under high temperature conditions, aluminum chromium alloys were electroplated on the TiAl alloy in an AlCl3-NaCl-KCl molten salt containing CrCl2 at 423 K. The deposit electroplated at -0.1 V vs. Al/Al3+ consists of gamma-Al8Cr5 single phase, including chromium content at 41 at.%. A mixture phase of gamma-Al8Cr5 and Al is, however, formed at potential from - 0.2 to - 0.4 V. The oxidation resistance of the electrodeposit layer was evaluated by a high temperature oxidation test at 1173 K for 24 h. On the TiAl specimen covered with gamma-Al8Cr5 which was deposited at -0.1 V, a uniform AlCr2 layer was formed during the oxidation at 1173 K. The AlCr2 layer was covered by a thin dense Al2O3. Both AlCr2 and Al2O3 layers play a role of superior protection from the high temperature oxidation of the TiAl alloy; therefore, the plating of the gamma-Al8Cr5 single layer deposited at -0.1 V reduced oxide thickness by 1/40 during the oxidation at 1173 K for 24 h from that on the TiAl without any plating. (C) 2003 Elsevier Science B.V. All rights reserved.
  • 宇井 幸一, 上田 幹人, 萩原 理加
    溶融塩および高温化学 電気化学会溶融塩委員会 47 (3) 114 - 123 0916-1589 2004 [Not refereed][Not invited]
  • UEDA Mikito, SUSUKIDA Daigo, KONDA Shouichi, OHTSUKA Toshiaki
    Journal of The Surface Finishing Society of Japan 一般社団法人 表面技術協会 54 (5) 363 - 366 0915-1869 2003/05/01 [Not refereed][Not invited]
     
    Anodic stripping of TiAl surface was carried out in AlCl3-NaCl-KCl molten salt at 423 K as a pretreatment for the deposit formation of an Al-Cr alloy layer. The Al-Cr alloy deposit on the TiAl significantly improved the corrosion resistance against high temperature oxidation. In anodic stripping at 0.4 V vs. Al/Al3+, anodic dissolution of surface occurred non-uniformly. On the other hand, an oxide film on TiAl was completely removed by uniform anodic dissolution at 1.2 V with electricity of 1 C cm-2. An Al-Cr electroplating layer that was formed after the anodic stripping at 1.2 V, exhibite...
  • Photoluminescence of Ti Oxide Film in Phosphate, Sulfate, and Chloride Solution
    Mikito Ueda, Toshiaki Ohtsuka
    Proceedings of the 13th Asian-Pacific Corrosion Control Conference F-07  2003 [Not refereed][Not invited]
  • Takahiro Domyo, Mikito Ueda, Toshiaki Ohtsuka
    Zairyo to Kankyo/ Corrosion Engineering 腐食防食協会 52 (8) 421 - 427 0917-0480 2003 [Not refereed][Not invited]
     
    Conductive polymer film of polypyrrole (PPy) doped by polymolybdate (PMo) anions was prepared on mild steels by anodic polymerization for corrosion prevention of the steels. The PPy-PMo conductive film prepared exhibits good adherence to the steel substrate. The mass and thickness of the PPy-PMo film linearly increase with electricity during constant current polymerization at 5 mA·cm-2. The density of the PPy-PMo polymer film was evaluated to be 2.5 g·cm-3 from the ratio of the mass to thickness. A corrosion test in neutral and acidic 3.5 wt% NaCl solutions was done for the steels covered by the PPy-PMo film. Corrosion of the steels is suppressed by the films: the corrosion rate in the neutral solution decreases by 1/3 compared with that of the bare steel and the rate in the acidic solution by 1/4. The film was gradually reduced during immersion in the solutions with progress of the corrosion reaction of Fe dissolution to Fe2+, which is accompanied with the dissolution from PMo in the film to MoO4 2- in the neutral solution, or with pickup of protons and sodium ions in the acidic solution.
  • M Ueda, H Dietz, A Anders, H Kneppe, A Meixner, W Plieth
    ELECTROCHIMICA ACTA 48 (4) 377 - 386 0013-4686 2002/12 [Not refereed][Not invited]
     
    Various structures of silver nanoparticles were generated by means of the double-pulse technique. The interaction of the pulse parameters was modeled to demonstrate that the electrodeposition of nanoparticles can be variably controlled. The results derived showed how to create nanoparticle structures with respect to size, density and monodispersity according to the application goal. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • M Ueda, T Ohtsuka
    CORROSION SCIENCE 44 (7) 1633 - 1638 0010-938X 2002/07 [Not refereed][Not invited]
     
    Luminescence light from the anodic thin oxide films formed on titanium in neutral phosphate solution was measured by photo-excitation of ultra-violet light irradiation with 3.82 eV energy. The luminescence light is observed with a peak of about 3 eV energy that corresponds to the band-gap energy of the n-type semiconductive TiO2 oxide. It can therefore be presumed that the luminescence is induced by de-excitation or recombination between electrons in the conduction band and holes in the valence band. The peak wavelength of the luminescence light changes with the formation potential of the oxide film from 409 nm at 1 V to 425 nm at 6 V. The shift of the peak may reflect an amorphous-crystalline transition with increase of potential. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • M Ueda, D Susukida, S Konda, T Ohtsuka
    MOLTEN SALTS XIII 2002 (19) 724 - 733 2002 [Refereed][Not invited]
     
    Al-Cr alloys were electroplated on the TiAl alloy in an AlCl3-NaCl-KCl molten salt containing CrCl2 at 423 K. The deposit consisting of gamma-Al8Cr5 single phase is obtained at potential of -0.1 V vs. Al/Al3+ and includes chromium content at 41 at%. The gamma-Al8Cr5 and Al mixture phase is, however, formed at potential from -0.2 to -0.4 V. The oxidation resistance of the electrodeposit was evaluated by a high temperature oxidation test at 1173 K for 24 h. The TiAl specimen with the Al-Cr deposit formed at -0.1 V is covered by the Cr2Al uniform layer and the thin dense Al2O3 layer after oxidation. For the TiAl specimen with the deposits formed from -0.2 to -0.4 V, however, the uniform protective layer does not form. The plating of the gamma-Al8Cr5 single phase deposit is found to reduce the oxide formation by 1/40 in thickness from that on the TiAl without the Al-Cr deposit by the oxidation.
  • M Ueda, T Ohmura, S Konda, T Sasaki, T Ohtsuka, T Ishikawa
    JOURNAL OF APPLIED ELECTROCHEMISTRY 31 (8) 871 - 875 0021-891X 2001/08 [Not refereed][Not invited]
     
    Electrorefining of aluminium was carried out at 750 degreesC using bipolar electrode cells with centre holes 2, 10 or 20 mm in diameter. Through the centre holes liquid electrorefined aluminium rises to the electrolyte surface. The bipolar electrode cell consists of graphite cathodes, Al-Cu-Fe-Mn or Al-Cu-Fe-Zn alloy anodes and a BaCl2-NaCl-AlF3-NaF electrolytic melt. The centre hole size of more 20 mm in diameter is required to continuously float up the aluminium electrodeposited onto the electrolyte surface, while the current efficiency of the cell decreases with increase of the centre hole size, from 97% at 2 mm diameter to 92% at 20 mm diameter. Aluminium of 99.97% purity precipitates at the cathode. Iron, manganese and zinc included in the alloy as impurities are hardly deposited and the concentrations of these elements in the deposit are 100, 80 and 170 ppm, respectively. In this process aluminium can be produced with an energy consumption of about 4.9 x 10(3) kWh(t-Al)(-1), which is one-third smaller than that of the Gadeau process.
  • Luminescence with Band-Gap Energy by UV-Light Excitation to Anodic Oxide Films on Titanium
    Mikito Ueda, Toshiaki Ohtsuka
    Proc. the 2nd Intern. Conf. on Environment Sensitive Cracking and Corrosion Damage 43 - 45 2001 [Not refereed][Not invited]
  • SATO Tadao, HORIGOME Takeshi, UEDA Mitito
    Journal of the Surface Finishing Society of Japan 一般社団法人 表面技術協会 51 (6) 640 - 645 0915-1869 2000/06/01 [Not refereed][Not invited]
     
    TiB2 and TiN films were coated by chemical vapor deposition on SKD 61 steel to improve the corrosion resistivity of a diecasting machine in a melted aluminum alloy. The protectivity of the film in the melted aluminum alloy was examined by an immersion test at 900°C and a thermal cycle test between room temperature and 900°C. TiN film, which serves as a binder, greatly improves the adhesion of TiB2 film on the steel substrate. The thermal cycle test indicated that the optimum thickness of TiB2 and TiN layers is at 4 and 6μm, respectively. Compared to ion-nitrized steel, steel coated by TiB2/...
  • 上田 幹人
    溶融塩および高温化学 電気化学協会溶融塩委員会 43 (3) 177 - 185 0916-1589 2000 [Not refereed][Not invited]
  • M Ueda, T Ohmura, S Konda, T Sasaki, T Ohtsuka
    MOLTEN SALTS XII, PROCEEDINGS 99 (41) 723 - 731 2000 [Refereed][Not invited]
     
    Electrorefining of aluminum was carried out at 750 degrees C by using a bipolar cell which has center holes with size 2, 10 or 20mm for easy upward flowing of the molten aluminum. The bipolar cell consists of graphite cathodes, Al-Cu-Fe-Mn or Al-Cu-Fe-Zn alloy anodes and BaCl2-NaCl-AlF3-NaF electrolytic melt. The efficiency of the cell is influenced by the center hole size: when the size of center holes increases, the efficiency decreases. However, a center hole size over 20mm diameter is required in order to allow a continuous flow electrodeposited aluminum on to the electrolytic melt surface. After electrolysis, it is found that very pure aluminum with 99.97% deposits on the cathode. Manganese and zinc dissolving from the anode alloy into the electrolytic melt hardly deposit on the cathode in the electrorefining process. Aluminum can be produced with energy consumption below 5,000kWh/t-Al with this process.
  • M Ueda, K Imasawa, S Konda, T Sasaki, T Ishikawa, T Ohtsuka
    ELECTROCHEMISTRY 67 (6) 695 - 699 1344-3542 1999/06 [Not refereed][Not invited]
     
    To decrease the reaction polarization of the cathodic reaction of Cl-2 +2e(-) --> 2Cl(-) in Al-Cl-2 electrochemical cell in NaCl-KCl melt at 1023 K, we developed a cell system with a vertically rotating electrode composed of sliced graphite disks which are partially immersed in the melt. The apparent reaction resistance of the cathodic reaction was evaluated from transient potential and current changes of the cell. The reaction resistance decreases with an increase of the number of the graphite disks. The resistance is a function of the rotation rate of the electrode and exhibits the minimum Value around a rotation rate of 20 rpm. The dependence on the rotation rate may be explained from Cl-2 concentration in a thin melt layer formed on the graphite electrode during exposure to Cl-2 gas phase. The rotation may introduce a continuous supply of the thin melt layer with a high concentration of Cl-2 to a reaction place at a meniscus part on the graphite electrode. However, if the rotation rate is too high, the exposure time of the thin melt layer to Cl-2 gas is not enough to establish an equilibrium concentration of Cl-2 in the layer.
  • M Ueda, M Amemiya, T Ishikawa, T Ohtsuka
    JOURNAL OF THE JAPAN INSTITUTE OF METALS 日本金属学会 63 (3) 279 - 283 0021-4876 1999/03 [Not refereed][Not invited]
     
    A new process for recovery of aluminum from aluminum dress was developed. The aluminum dress which is obtained as a by-product during casting process of aluminum alloy contains aluminum alloy and oxides of various metals including aluminum oxide. The process consists of two stages: (1) Separation of the aluminum alloy from the oxides by difference in density between the alloy and the oxide in molten salts. (2) Dissolution of oxides into molten salts, and electrolysis of the molten salts to form metallic aluminum from the oxide. This paper is concerned with the first stage for the separation of the aluminum alloy from the oxides by using BaCl2-NaCl-NaF melts. The aluminum alloy completely separates from the oxides in the melts at concentrations of BaCl2 higher than 33.3 mol%, in which the liquid aluminum alloy floats up and the oxides sink down. From a 30 g dress sample, amount of about 24 g of aluminum alloy has been recovered. The remaining oxides contains aluminum oxide, silicon oxide, magnesium oxide and iron oxide. From the aluminum oxide dissolved in the melt, metallic aluminum is formed by electrolysis in a subsequent stage.
  • ISHIKAWA Tatsuo, UEDA Mikito
    Journal of the Surface Finishing Society of Japan 一般社団法人 表面技術協会 49 (4) 347 - 351 0915-1869 1998/04/01 [Not refereed][Not invited]
  • UEDA Mikito, KONDA Shoichi, SASAKI Takeshi, ISHIKAWA Tatsuo
    Electrochemistry 電気化学会 66 (2) 164 - 170 1344-3542 1998/02/05 [Not refereed][Not invited]
  • M Ueda, S Konda, T Sasaki, T Ishikawa
    DENKI KAGAKU 66 (2) 164 - 170 0366-9297 1998/02 [Refereed][Not invited]
     
    Anodic dissolution behavior of several aluminum alloys containing Fe(1 similar to 3 mass%), Si(0.2 similar to 3 mass%) and Mg (0.3 mass%) was investigated in molten salts predominantly composed of chloride, which were developed for electrorefining of aluminum from aluminum scraps in a three-layer cell. During 12 hour electrolysis using the aluminum alloys, the aluminum content in the melts, 5 mol% AlF3-NaF-BaCl2-NaCl, was kept constant and the overvoltage of both anodic and cathodic reactions was negligibly small. It suggested that the melts were applicable to the system for Al electrorefining. The analysis of the melts and the deposited Al every three hours showed that Fe content in the deposited Al was less than 0.01 mass% and that of Mg was negligibly small, and the contents of Si became about one thirtieth of the starting anode alloys. The Fe content up to 3 mass% in anode alloys brought about no significant problems.
  • KONDA Shoichi, SASAKI Takeshi, UEDA Mikito, ISHIKAWA Tatsuo
    Electrochemistry 電気化学会 66 (1) 80 - 85 1344-3542 1998/01/05 [Not refereed][Not invited]
  • KONDA Shoichi, SASAKI Takeshi, UEDA Mikito, ISHIKAWA Tatsuo
    Electrochemistry 電気化学会 66 (1) 74 - 79 1344-3542 1998/01/05 [Not refereed][Not invited]
  • M Ueda, T Sasaki, S Konda, T Ishikawa
    PROCEEDINGS OF THE ELEVENTH INTERNATIONAL SYMPOSIUM ON MOLTEN SALTS XI 98 (11) 363 - 369 1998 [Refereed][Not invited]
     
    To investigate the applicability of a vertically stacked bipolar electrode cell to electrorefining of Al from scrap Al, the cell composed of three units was made with anode 61%Al - 37.3%Cu alloy containing 1%Fe and 0.7% Mn (mass) in melt and electrolysis was carried out for six hours at 750 degrees C. As the electricity of 90 Ahr, which corresponded to Al deposition of 30.0g per cathode in 100% current efficiency, was applied, the total mass of electrodeposited Al was 87.5g. The amounts of Mn, Cu and Fe in deposited Al were under 0.003, 0.008 and 0.009 %, respectively; the purity of Al exceeded 99.98%. The concentration of Al components in the 3rd unit containing a terminal anode increased compared with the initial concentration, and that in the Ist unit containing a terminal cathode decreased. It was interpreted that the reaction current through bipolar electrodes became small due to bypass current, and the bipolar electrodes worked almost ideally. The vertically stacked bipolar electrode cell is, therefore, useful for electrorefining of Al from scrap Al, if same counterpane to dissolve the ununiformity of the concentration in the cell is laid down.
  • S Konda, T Sasaki, M Ueda, T Ishikawa
    DENKI KAGAKU 66 (1) 74 - 79 0366-9297 1998/01 [Refereed][Not invited]
     
    In order to develop an energy saving process for electrowinning of liquid aluminum from chloride melts, a design principle for a bipolar electrode cell was developed and the design parameters suitable for its operation were determined on the basis of experiments in 25 mol %MgCl2-75mol%NaCl melts containing several mol% AlCl3 at 750 degrees C.
  • S Konda, T Sasaki, M Ueda, T Ishikawa
    DENKI KAGAKU 66 (1) 80 - 85 0366-9297 1998/01 [Refereed][Not invited]
     
    The decomposition voltage of aluminum chloride and the electrical conductivity were determined as a function of concentration of aluminum chloride in 25 mol%MgCl2-NaCl melts in order to estimate the characteristics of a bipolar electrode cell. The relations between voltage and applied current were calculated from an equivalent circuit of the bipolar electrode cell of which components were determined by using these properties of the melts and the parameters of the cell design. The calculated relations were in fair agreement with the experimental results. This suggests that the procedure mentioned above makes it possible for us to estimate the characteristics of the cell and select the suitable electrolysis conditions without the operation of the cell.
  • UEDA Mikito, KONDA Shoichi, SASAKI Takeshi, ISHIKAWA Tatsuo
    Electrochemistry 電気化学会 64 (9) 978 - 983 1344-3542 1996/09/05 [Not refereed][Not invited]
  • M Ueda, S Konda, T Sasaki, T Ishikawa
    DENKI KAGAKU 64 (9) 978 - 983 0366-9297 1996/09 [Refereed][Not invited]
     
    Electrical conductivity of chloride melts containing fluorides expected to be useful as an Al electrorefining bath was measured by changing distances between a graphite cathode and an aluminum-copper alloy anode. The melts were prepared by adding prescribed amounts of a 40 mol%5 AlF3-NaF double salt to 40 similar to 60 mol% BaCl3-NaCl solvent melts and investigated in the concentration range of AlF3 from 5 to 15 mol%. Electrical conductivities of the melts were determined to be in the region of 2.0 to 2.8 S . cm(-1) at 750 similar to 850 degrees C and the activation energies varied from 1.9 to 2.8 kJ . mol(-1). The electrical conductivity increased with an increase of AlF3 concentration in 50 and 60 mol% BaCl2-NaCl solvent melts, but it decreased in the 40 mol% BaCl2-NaCl solvent melt. The increases in conductivity were due to increase in the mole fraction of Na components in the melts by the addition of 40 mol% AlF3-NaF double salts. The cause for the decrease was also discussed in terms of the increase in complex anions derived from AlF3.
  • UEDA Mikito, KONDA Shoichi, SASAKI Takeshi, ISHIKAWA Tatsuo
    Electrochemistry 電気化学会 63 (7) 664 - 668 1344-3542 1995/07/05 [Not refereed][Not invited]

Books etc

  • 電気化学便覧
    上田幹人 (Contributor溶融塩・イオン液体、工業電解)
    丸善出版 2012/12
  • リサイクル・廃棄物辞典
    上田幹人 (Contributor近未来の技術と可能性)
    産業調査会 2012/03
  • イオン液体II
    上田幹人 (Contributorイオン液体の定義)
    シーエムシー出版 2006/03

MISC

Awards & Honors

  • 2020/01 Electrochemical society Japan, Molten Salt committee Molten Salt Award
     溶融塩・イオン液体を用いた金属電気化学 
    受賞者: Mikito Ueda
  • 2003/04 電気化学会 進歩賞（佐野賞）
     
    受賞者: 上田幹人

Research Grants & Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2021/04 -2024/03 
    Author : 上田 幹人
     
    電場の有無によるアルミニウムイオンの電極界面における分布を調べるため、基礎データとして、塩化アルミニウム6水和物(AlCl3・6H2O)を用いて0.1M水溶液を調製し、高配向性熱分解グラファイト（HOPG）上のアルミニウムイオンの吸着特性を調べた。 純水または調製した水溶液をHOPG上に滴下し、原子間力顕微鏡(AFM)カンチレバーを液滴の中に入るように設定し、コンタクトモードでフォースカーブ(FC)測定を行った。FC測定で得られるデータは、カンチレバーがそれぞれの位置でチップの先端が受ける反力の値である。純水の場合は、HOPG上に吸着する水分子の斥力を測定する事となり、AlCl3水溶液の場合は、水分子の他にアルミニウムイオンの斥力も測定していると考えられる。 測定結果から、純水の場合はHOPG基板にカンチレバーの探針が到達するまでに1段階のギャップがあったが、AlCl3水溶液の場合は、それが二段階になっていた。さらに詳細な解析の結果、その二段のギャップはHOPG基板から1nmの距離の範囲で観察され、おそらく水分子と水和したアルミニウムイオンの大きさに対応しているものと考えられる。 これまでの報告によれば、水和したアルミニウムイオン[Al(H2O)6]3+の大きさは直径にして0.66nmと推定している例もあり、サイズとして1nm以下で2段階のギャップがあることは、妥当な測定結果と考えられる。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2015/04 -2017/03 
    Author : Ueda Mikito
     
    In this study, formation of sodium hydride was investigated by electrochemical method. Electrochemical measurements as basic study were carried out in NaTFSI-TEATFSI mixture ionic liquid with hydrogen bubbling or argon bubbling. In the argon bubbling, cathodic current of only sodium electrodeposition was observed.In the hydrogen bubbling, the other cathodic current was observed at higher potential than it of sodium electrodeposition. This result suggests the formation of sodium hydride by electrochemical method.

Educational Activities

Teaching Experience

  • Advanced Eco-Materials
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 環境劣化，腐食，防食，局部電池モデル，不働態皮膜，電気化学、資源リサイクル
  • Advanced Eco-Materials
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 環境劣化，腐食，防食，局部電池モデル，不働態皮膜，電気化学、資源リサイクル
  • Engineering of Materials Design
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 金属材料、電子、原子、結晶構造、機能性、構造材、表面、反応プロセス
  • Introduction to Materials Engineering
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 金属材料、電子、原子、結晶構造、機能性、構造材、表面、反応プロセス
  • Materials Thermodynamics
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 活量、化学ポテンシャル、溶液、電気化学，
  • Environment and People
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : マテリアル製造、製造プロセス、省エネルギー、地球環境、持続的発展
  • Exercise in Materials Science I
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 化学ポテンシャル、活量、化学平衡、X線結晶解析、X線回折、結晶構造、ミラー指数、逆格子 　　
  • Engineering for Material Processing
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 材料熱力学、高温反応プロセス、非鉄金属の製造、座標系、反応操作、分離操作、分子運動論と真空科学技術
  • Exercise in Materials Science III
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 二元系・三元系平衡状態図、自由エネルギー・組成図、材料熱力学、混合と相平衡、気体の関与する状態図、真空技術、活量、座標系、反応操作、分離操作、精錬反応

Social Contribution

Social Contribution

Others

  • 2011/11 -2011/11 北海道大学説明会(名古屋、大阪にて開催) 工学部担当
  • 2011/07 -2011/07 北見工業大学 非常勤講師
  • 2010/11 -2010/11 北海道大学説明会 (東京にて開催) 工学部担当
  • 2009/11 -2009/11 北海道大学説明会(東京にて開催) 工学部担当
  • 2009/09 -2009/09 北海道大学工学部 工学セミナー（釧路にて開催） 講師
  • 2009/08 -2009/08 北海道大学セミナー（函館にて開催） 工学部の講師
  • 2008/08 -2008/08 北海道大学工学部 工学セミナー(函館にて開催) 講師
  • 2007 -2007 北海道大学工学部北工会 文化部長

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