Papers - SAKAI Go
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Sakai G., Nakatani T., Yoshimura T., Uota M., Kijima T.
Chemistry Letters 34 ( 10 ) 1364 - 1365 2005.10
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Chemistry Letters
The spherical microparticles of SnO 2 were synthesized successfully by hydrothermal treatment of their precursor consisting of SnCl 4 and mixed surfactants, followed by calcination at 500°C. Copyright © 2005 The Chemical Society of Japan.
DOI： 10.1246/cl.2005.1364
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Synthesis of Polycrystalline Spherical SnO2 Microparticles via Hydrothermal Treatment in the Presence of Mixed Surfactants Reviewed
共著者：G. Sakai, T. Nakatani, T. Yoshimura, M. Uota, T. Kijima
Chemistry Letters, Vol. 34, No. 10, 1364-1365 (2005). 34 ( 10 ) 1364 - 1365 2005.10
Language：English Publishing type：Research paper (scientific journal)
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Cho H., Sakai G., Shimanoe K., Yamazoe N.
Sensors and Actuators, B: Chemical 109 ( 2 ) 307 - 314 2005.9
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
A group of complex metal oxides, BiMeVOx, which a fraction (x) of V in Bi4V2O11is replaced by foreign metal, has been reported to be oxide-ionic conductors. The various kinds of oxides in this group, Me = Cu (x = 0.1), Zr (x = 0.1), Ti (x = 0.4), Nb (x = 0.15) and Ta (x = 0.15), were investigated for electrochemical characterization based on oxygen concentration battery. The powders of BiMeVOx, their structural phases to the high temperature phase (γ) of Bi4V2O11, were obtained by calcining at 700-850 °C. Each sample was compacted into a disk, and installed into an oxygen concentration cell. The oxygen concentration cells using the resulting disks of BiMeVOx, especially Me = Cu, were found to work as an oxygen sensor fairly well at 700 °C: the number of reaction electrons (n) associated with the reduction of O2was close to the theoretical one (4). With lowering operating temperature, however, the O2-responding properties degraded rather quickly: it was far larger at 500 °C. Such degradation was confirmed to be owing to decrease the rate of electrode reactions through the measurement of Faraday efficiency of oxygen pumping current. As a result, the performances of the cells were found to depend very much on the kinds of electrode materials. The use of a perovskite-type oxide, La0.6Sr0.4Co0.8Fe0.2O3, instead of Pt as a electrode was found to enable the cell to work at 400 °C and above. © 2005 Elsevier B.V. All rights reserved.
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Preparation of BiMeVOx (Me = Cu, Ti, Zr, Nb, Ta) compounds as solid electrolyte and behavior of their oxygen concentration cells
共著者：H. S. Cho, G. Sakai, K. Shimanoe, N. Yamazoe
Sensors and Actuators B, 109, 307-314 (2005). 109 307 - 314 2005.9
Language：English Publishing type：Research paper (scientific journal)
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Behavior of oxygen concentration cells using BiCuVOx oxide-ion conductor
Cho H., Sakai G., Shimanoe K., Yamazoe N.
Sensors and Actuators, B: Chemical 108 ( 1-2 SPEC. ISS. ) 335 - 340 2005.7
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
The mixed oxide, Bi2Cu0.1V0.9O5.35often abbreviated as BiCuVOx, is known as an oxide-ionic conductor. The applicability of this oxide to a potentiometric oxygen sensor was investigated. Oxygen concentration cells were fabricated by using a disk of this oxide to test the EMF response to changes in oxygen concentration between 10% and 100% at various temperatures between 300 and 700 °C. As a result, the performances of the cells were found to depend very much on the kinds of electrode materials. When attached with Pt electrodes, the cell produced the EMF response fairly good only at 600 °C and above, whereas the oxide-ion transport number was close to unity even at 500 °C as evaluated from the Faraday efficiency of oxygen pumping current. The use of a perovskite-type oxide (La0.6Sr0.4Co0.8Fe0.2O3) instead of Pt was found to enable the cell to work at 400 °C and above. Especially excellent performances were observed when the oxide was mixed with BiCuVOxpowder prior to being applied on the BiCuVOxdisk as the electrodes. © 2004 Elsevier B.V. All rights reserved.
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Development of SnO<inf>2</inf>-based gas sensor sensitive to dilute ethylene oxide in air
Kugishima M., Sakai G., Shimanoe K., Yamazoe N.
Sensors and Actuators, B: Chemical 108 ( 1-2 SPEC. ISS. ) 130 - 133 2005.7
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
In order to enhance sensitivity to C2H4O for the medical safety purpose, foreign additives (e.g. La2O3, SrO and CaO) were loaded on SnO2powder. Among the additives tested, La2O3proved itself to be a promising promoter for the sensitivity. On the other hand, the response and recovery rates were found to be deteriorated with La2O3. The rates were accelerated considerably when the La2O3-loaded SnO2was further added with Pd or Pt. The device using Pt (0.5 wt.%)-La2O3(0.5 wt.%)-SnO2thus prepared showed sensor response exceeding 10 to 1 ppm C2H4O as well as fairly good response rates under dry condition at 300 °C, where response was defined as the resistance ratio (Rair/Rgas). © 2004 Elsevier B.V. All rights reserved.
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Miyachi Y., Sakai G., Shimanoe K., Yamazoe N.
Sensors and Actuators, B: Chemical 108 ( 1-2 SPEC. ISS. ) 364 - 367 2005.7
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
A planar type CO2sensor device using NASICON (Na+conductor, Na3Zr2Si2PO12) thick film was attached with a glass (SiO2:Na2O:B2O3:Al2O3= 44:20:31:5, in molar ratio)-coated Na0.6CoO2reference electrode to increase its feasibility under various conditions in practical. The fabricated device proved satisfactory CO2-sensing properties at steady operating temperature (450 °C) under dry and humid conditions. In the heat-cycle tests between the operating temperature and room temperature under various humid conditions, the planar device once aged, exhibited quick warm-up characteristics and well-reproducible EMF response to CO2unless humidity was very high (e.g. 80%). © 2004 Elsevier B.V. All rights reserved.
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Development of SnO2-based gas sensor sensitive to dilute ethylene oxide in air Reviewed
共著者：M. Kugishima, G. Sakai, K. Shimanoe, N. Yamazoe
Sensors and Actuators B, 108, 130-133 (2005). 108 130 - 133 2005.7
Language：English Publishing type：Research paper (scientific journal)
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Behavior of oxygen concentration cells using BiCuVOx oxide-ion conductor
共著者：H. Cho, G. Sakai, K. Shimanoe, N. Yamazoe
Sensors and Actuators B, 108, 335-340 (2005). 108 335 - 340 2005.7
Language：English Publishing type：Research paper (scientific journal)
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Improvement of warming-up characteristics of potentiometric CO2 sensor by using solid reference counter electrode Reviewed
共著者：Y. Miyachi, G. Sakai, K. Shimanoe, N. Yamazoe
Sensors and Actuators B, 108, 364-367 (2005). 108 364 - 367 2005.7
Language：English Publishing type：Research paper (scientific journal)
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Sensing properties of Au-loaded SnO2-Co3O4 composites to CO and H2 Reviewed
共著者：U.-S. Choi, G. Sakai, K. Shimanoe, N. Yamazoe
Sensors and Actuators B, 107, 397-401 (2005). 107 397 - 401 2005.6
Language：English Publishing type：Research paper (scientific journal)
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Sensing properties of Au-loaded SnO2-Co3O4 composites to CO and H2
Choi U., Sakai G., Shimanoe K., Yamazoe N.
Sensors and Actuators, B: Chemical 107 ( 1 SPEC. ISS. ) 397 - 401 2005.5
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
Two kinds of SnO2-Co3O4composites, SC1 and SC50, the Co3O4contents of which were 1 and 50 mass%, respectively, were loaded with small amounts of Au (0.05, 0.5 and 1 mass%). The thick film device using SC1, characterized by high sensitivity to both CO and H2at 250 °C, was found to be made more sensitive without significant alterations of selectivity between CO and H2as the amount of Au-loaded increased up to 0.5%, while the addition of 1 mass% Au degraded the sensing properties seriously. Similar promoting effects of Au were recognized for the SC50-based devices, which were p-type semiconductors responding fairly selectively to CO over H2at 100 °C. The promoting effects of Au were discussed briefly based on the behavior of electrical resistances of the Au-loaded devices. © 2004 Elsevier B.V. All rights reserved.
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Vuong D., Sakai G., Shimanoe K., Yamazoe N.
Sensors and Actuators, B: Chemical 105 ( 2 ) 437 - 442 2005.3
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
Sols of crystalline SnO2with different mean grain (crystallite) sizes between 6 and 16 nm were prepared by subjecting stannic acid gel to hydrothermal treatments under various conditions. Thin film sensor devices with different film thicknesses between 200 and 900 nm were fabricated to investigate sensing properties to H2S gas. It was found that the sensor response to H2S, defined as the ratio of resistance in air to that in H2S-containing air, was greatly enhanced with decreasing film thick and with increasing grain size up to 16 nm, as expected from the gas diffusion-reaction theory. The response was surprisingly large, exceeding 104at 150 °C, for the device deposited with a 200 nm-thick film of SnO212 nm in grain size. © 2004 Elsevier B.V. All rights reserved.
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Hydrogen sulfide gas sensing properties of thin films derived from SnO2 sols different in grain size Reviewed
共著者：D. D. Vuong, G. Sakai, K. Shimanoe, N. Yamazoe
Sensors and Actuators B, 105 (2), 437-442 (2005). 105 ( 2 ) 437 - 442 2005.3
Language：English Publishing type：Research paper (scientific journal)
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mori hiroshi, uota Masafumi, Fujikawa Daisuke, Yoshimura Takumi, Sakai Go, Kijima Tsuyoshi, Kuwahara Takeshi
Preprints of Annual Meeting of The Ceramic Society of Japan<br>Preprints of Fall Meeting of The Ceramic Society of Japan 2005 ( 0 ) 295 - 295 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Ceramic Society of Japan
having mesopores of 6-8 nm in pore-to-pore distance (The pore-size distribution obtained by N2 adsorption-desorption isotherm is 5 nm)and micropores of about 0.4nm in size.
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Synthesis and Luminessence properties of Eu(_III_)-Doped Y<SUB>2</SUB>O<SUB>2</SUB>SO<SUB>4</SUB>
Shinbori Tomohiro, Sakai Go, Kijima Tsuyoshi
Preprints of Annual Meeting of The Ceramic Society of Japan<br>Preprints of Fall Meeting of The Ceramic Society of Japan 2005 ( 0 ) 300 - 300 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Ceramic Society of Japan
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Morphologically controlled synthesis of nanocarbons from resorcinol-based nanopolymers
Fujikawa Daisuke, Uota Masafumi, Yoshimura Takumi, Sakai Go, Kijima Tsuyoshi
日本セラミックス協会 年会・秋季シンポジウム 講演予稿集 2005 ( 0 ) 617 - 617 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：公益社団法人 日本セラミックス協会
Much attention has been paid to the synthesis of inorganic nanomaterials by the sol-gel method combined with organic templating approach. Polymerization of resorcinol and formaldehyde (R-F) proceeds through the sol-gel process similar to that for metal alkoxide. This motivated us to apply the surfactant approach to the R-F system. Here we report the synthesis of rope-like, spherical and wire-like polymer particles as well as their conversion into carbons with essentially the same morphologies.
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Oxygen reduction properties of spongy platinum nanosheets loaded carbon
Sakai Go, Isohata Shusaku, Yoshimura Takumi, Kuwahara Takeshi, Uota Masafumi, Kawasaki Hideya, Kijima Tsuyoshi
日本セラミックス協会 年会・秋季シンポジウム 講演予稿集 2005 ( 0 ) 253 - 253 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：公益社団法人 日本セラミックス協会
Recently, our research group found that spongy platinum nanosheets are obtained by reducing Pt salts with sodium boron hydride (SBH) within mixed-surfactant liquid crystal templates. In this study, an attempt was made to load such Pt nanosheets on carbon-support with keeping the nano-structure. Electrochemical study revealed that the spongy Pt nanosheets loaded carbon has large electrochemically active surface area of Pt, and fairly high in electrochemical oxidation and reduction activity. Especially, the observed oxygen reduction activity was higher than that of commercially available ones.
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Synthesis of nanocarbons from morphologically controlled resorcinol-based nanopolymers
Fujikawa Daisuke, Uota Masafumi, Yoshimura Takumi, Sakai Go, Kijima Tsuyoshi
Preprints of Annual Meeting of The Ceramic Society of Japan<br>Preprints of Fall Meeting of The Ceramic Society of Japan 2005 ( 0 ) 390 - 390 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Ceramic Society of Japan
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Sakai Go, Nakatani Tomoe, Masaki Takanori, Kijima Tsuyoshi
Preprints of Annual Meeting of The Ceramic Society of Japan<br>Preprints of Fall Meeting of The Ceramic Society of Japan 2005 ( 0 ) 701 - 701 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Ceramic Society of Japan