Papers - SAKAI Go
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Semiconductor Gas Sensor Using SrO-Modified SnO2 for the Detection of N2O in Air Reviewed
共著者：E. Kanazawa, G. Sakai, K. Shimanoe, Y. Kanmura, Y. Teraoka, N. Miura, N. Yamazoe
Electrochemical and Solid-State Letters, Vol. 3, No. 12, 572-574 3 ( 12 ) 572 - 574 2000.12
Language：English Publishing type：Research paper (scientific journal)
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Kanazawa E., Sakai G., Shimanoe K., Kanmura Y., Teraoka Y., Miura N., Yamazoe N.
Electrochemical and Solid-State Letters 3 ( 12 ) 572 - 574 2000.12
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemical and Solid-State Letters
A semiconductor-type sensor applicable to the monitoring of N2O in air was studied. As revealed by a screening test, n-type oxides such as SnO2, In2O3, WO3, and ZnO were more or less sensitive to N2O, while the highest sensitivity was obtained with SnO2. However, the N2O sensitivity of SnO2was not sufficient for practical application. The addition of SrO to SnO2was effective for improving N2O sensitivity. Thus 0.5 wt % SrO-SnO2was about three times as sensitive as pure SnO2, allowing good detection of 10-300 ppm N2O in air at 500 °C.
DOI： 10.1149/1.1391212
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糖尿病診断を目指した呼気中アセトン検出用薄膜型酸化物半導体ガスセンサ Reviewed
共著者：酒井 剛、元岡功一、三浦則雄、山添 曻
電気学会準部門誌E、Vol.-120-E,No. 10, 476-481 120-E ( 10 ) 476 - 481 2000.10
Language：Japanese Publishing type：Research paper (scientific journal)
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Hydrothermal treatment of tin oxide sol solution for preparation of thin-film sensor with enhanced thermal stability and gas sensitivity Reviewed
共著者：N.-S. Baik, G. Sakai, K. Shimanoe, N. Miura, N. Yamazoe
Sensors and Actuators B,Vol. 65, 97-100 65 97 - 100 2000.7
Language：English Publishing type：Research paper (scientific journal)
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Spin-coated indium oxide thin film on alumina and silicon substrates and their gas sensing properties Reviewed
共著者：W.-Y. Chung, G. Sakai, K. Shimanoe, N. Miura, D.-D. Lee, N. Yamazoe
Sensors and Actuators B, Vol. 65, 312-315 65 312 - 315 2000.7
Language：English Publishing type：Research paper (scientific journal)
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Phase Transformation and Oxygen Permeation Properties of Partially Substituted Strontium Cobaltite -Influences of B-site Partial Substitution- Reviewed
共著者： H. Kusaba, G. Sakai, N. Miura, N. Yamazoe
Ionics, Vol, 6, 47-56 6 47 - 56 2000.7
Language：English Publishing type：Research paper (scientific journal)
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Baik N., Sakai G., Shimanoe K., Miura N., Yamazoe N.
Sensors and Actuators, B: Chemical 65 ( 1 ) 97 - 100 2000.6
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
The effects of treating tin oxide gel hydrothermally in an ammonia solution at 200 °C for 3 h were studied. The size of sol particles increased with increasing concentration of the resulting sol solution, i.e., 5, 8, 10 and 32 nm for 1.8, 3.2, 6.1 and 8.6 wt.% tin oxide sol as determined by an optical analyzer, whereas the crystallite size of tin oxide determined by X-ray diffraction analysis remained to be about 5-7 nm for all the solutions. The tin oxide powder collected was found to be resistant to grain growth on calcination, depending on the concentration of the sol solution. This tendency was maintained in the thin-films spin-coated on an alumina substrate from the sol solutions. The grain size of the film derived from 1.8 wt.% tin oxide sol was smaller than 10 nm in diameter after calcination at 600 °C. This particular film exhibited an outstanding by high sensitivity to 800 ppm H2at 350 °C, compared with conventional tin oxide elements of a sintered block type.
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Chung W., Sakai G., Shimanoe K., Miura N., Lee D., Yamazoe N.
Sensors and Actuators, B: Chemical 65 ( 1 ) 312 - 315 2000.6
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
Thin films of indium oxide were prepared on alumina and silicon substrates by spin-coating from an aqueous acetic acid solution dissolving In(OH)3and ammonium carboxymethyl cellulose. The films could cover well the large grains of rough alumina as well as the flat surface of silicon. By changing the number of spin-coating, the film thickness was well controlled between 70 nm and 210 nm on alumina or between 65 nm and 220 nm on silicon, as observed by cross-sectional FE-SEM. Gas sensing properties including sensitivity, selectivity and the rates of response and recovery were strongly dependent on the kind of substrate, film thickness and operating temperature.
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Kusaba H., Sakai G., Miura N., Yamazoe N.
Electrochemistry 68 ( 6 ) 409 - 411 2000.6
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrochemistry
The relation between oxygen permeation and phase transformation of A- and B-site partially substituted strontium cobaltites, Sr0.9Ca0.1Co1-xB′xO2.5 + δ (B′= Co, Mn, Ni, In, Fe or Al), were examined. As analyzed by high-temperature XRD, all of these oxides transformed into perovskite-type structure at elevated temperatures. The transformation temperatures of the last two oxides (B′= Fe or Al) were lower than those of the others. Noticeably, the phase transformation temperatures coincided with the temperature at which oxygen permeation switched on. The lowest switching-on temperature (750°C) was observed with the Fe-substituted oxide among the above oxides.
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Oxygen Permeability and Phase Transformation of Strontium-Cobaltite System. -Effect of B-site Substitution
共著者：H. Kusaba, G. Sakai, N. Miura, N. Yamazoe
Electrochemistry, Vol. 68, No. 6, 409-411 68 ( 6 ) 409 - 411 2000.6
Language：English Publishing type：Research paper (scientific journal)
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Hydrothermally treated sol solution of tin oxide for thin-film gas sensor
Baik N., Sakai G., Miura N., Yamazoe N.
Sensors and Actuators, B: Chemical 63 ( 1 ) 74 - 79 2000.4
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical
A sol solution containing SnO2particles (crystallites) of 6 nm in average diameter was prepared by a hydrothermal treatment. The hydrothermal treatment was found to be very effective for suppressing the thermal growth of SnO2grains. A thin-film sensor device, fabricated by spin-coating from the sol solution, consisted of SnO2crystallites with 6 nm in mean diameter after calcination at 600 °C. The device proved for better properties in sensitivity and response transient than a conventional sintered-block sensor device using SnO2precipitated gel.
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Jinkawa T., Sakai G., Tamaki J., Miura N., Yamazoe N.
Journal of Molecular Catalysis A: Chemical 155 ( 1-2 ) 193 - 200 2000.4
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Molecular Catalysis A: Chemical
A semiconductor gas sensor using SnO2was loaded with acidic or basic oxides (5 wt.%) to investigate ethanol-gas sensing properties and related catalytic properties. The sensitivity to ethanol gas at 300°C increased tremendously with an addition of a basic oxide (e.g., La2O3), while it hardly changed with that of an acidic oxide (WO3). It turned out that the addition of the basic metal oxide to SnO2brought about enhancement of catalytic activity not only for the dehydrogenation of ethanol gas to CH3CHO but also for the consecutive oxidation of CH3CHO to CO2. On the other hand, the acidic metal oxide enhanced only the dehydration reaction, showing even an adverse effect on the consecutive oxidation. Based on these results, it was concluded that the enhancement of the catalytic oxidation activity to an appropriate level could be a reason for the high sensitivity to ethanol gas for the sensors loaded with basic oxides, particularly one loaded with La2O3. (C) 2000 Elsevier Science B.V.
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Hydrothermally treated sol solution of tin oxide for thin-film gas sensor
共著者：N. ?S. Baik, G. Sakai, N. Miura, N. Yamazoe
Sensors and Actuators B, Vol. 63/1-2, 73-79 63 ( 1-2 ) 73 - 79 2000.4
Language：English Publishing type：Research paper (scientific journal)
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Relationship between ethanol gas sensitivity and surface catalytic property of tin oxide sensors modified with acidic or basic oxides
共著者：T. Jinkawa, G. Sakai, J. Tamaki, N. Miura, N.Yamazoe
Journal of Molecular Catalysis A, Vol. 155(1-2), 193-200 2000.4
Language：English Publishing type：Research paper (scientific journal)
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Preparation of stabilized nanosized tin oxide particles by hydrothermal treatment
Baik N., Sakai G., Miura N., Yamazoe N.
Journal of the American Ceramic Society 83 ( 12 ) 2983 - 2987 2000.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of the American Ceramic Society
Stable colloidal suspensions of tin oxide (content 0.9-6.1 wt%) were synthesized by subjecting conventionally prepared tin oxide gels to hydrothermal treatment with an ammonia solution (pH 10.5) at 200°C for 3 h in an autoclave. Based on X-ray diffractometry analyses, the tin oxide crystallites after hydrothermal treatment were resistant to thermal growth at elevated temperatures, and this feature became more conspicuous as the tin oxide content of the colloidal suspension decreased. For the powder derived from a 1.8 wt% colloidal suspension, for example, the mean sizes of the tin oxide crystallites were 7.5 and 13 nm after calcination at 600° and 900°C, respectively, in comparison with corresponding values of 13.5 and 29 nm for the untreated gel-derived powder. Thin film spin-coated from the same suspension had good uniformity, packed with tin oxide grains (crystallites) of a mean size of 6 nm after calcination at 600°C. Optical determination of the tin oxide sol particle size, as well as gravimetric analysis of the dehydration from the powder samples, were conducted to determine effects of hydrothermal treatment.
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Kusaba H., Sakai G., Miura N., Yamazoe N.
Ionics 6 ( 1-2 ) 47 - 56 2000.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Ionics
A group of B-site partially substituted stron.tium cobaltites Sr0.9Cao.1COo.9B'0.1O2.5+8(B'=Mn, Co, Ni, In, Fe and AI) were examined for phase transformation and oxygen permeation properties. As revealed by XRD analysis, these oxides had 2H-BaNiO3-type structure (B'=Mn, Co, Ni and In) or brownmillerite-type structure (B'=Fe and A1) and transformed into perovskite-type structure at elevated temperatures (750 °C or above). The transformation temperature was dependent on the B-site substituent and agreed well with the switching-on temperature of oxygen permeation for the same oxide. Due to a lowering in transformation temperature, the Fe- or Al-doped oxide was made oxygen permeable in the lower temperature range 750-850 °C where the undoped oxide remained non-permeable. It was also found that for a series of Fe-partially substituted samples Sr09Cao°CCol. °CFe°CO25+5the transformation temperature lowered with increasing x up to 0.1, while, for x ≥ 0.2, perovskite-type structure tended to be stabilized at room temperature. TGDTA analysis revealed that phase transformation was accompanied by absorption or desorption of oxygen. Based on the correlation between the oxygen permeability and the membrane thickness, the rate-determining step of oxygen permeation in the present system was assumed to be of the bulk diffusion of oxide ion vacancies.
DOI： 10.1007/BF02375546
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Sakai G., Motooka K., Miura N., Yamazoe N.
IEEJ Transactions on Sensors and Micromachines 120 ( 10 ) 476 - 481 2000
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Sensors and Micromachines
Thin-film-type oxide semiconductor gas sensors sensitive to acetone were explored for the diagnosis of diabetes. SnO2 and ZnO were tested as a base sensor material. When fabricated into a thick-film-type sensor, SnO2 was inferior to ZnO in the acetone sensitivity. However, on changing to a thin-film-type sensor, SnO2 proved to be more sensitive to acetone than ZnO. The acetone sensitivity of the SnO2-based thin film sensor could be improved by the addition (0.1 wt%) of noble metals, such as Rh and Ru. The resulting sensor using Rh-SnO2 could detect as dilute as 0.2 ppm acetone in human expiration at 300∘ without being disturbed by changes in O2 and CO2 concentrations. © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.
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SPR免疫センサによるメタンフェタミン（覚醒剤）の高感度検出とその抗原抗体反応解析
共著者：中田聖士、酒井 剛、宇田泰三、三浦則雄、山添 曻
電気学会E部門誌、センサ・マイクロマシン部門誌、Vol. 119-E, 581-586頁 1999.11
Language：English Publishing type：Research paper (scientific journal)
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Oxygen permeability and phase transformation of Sr<inf>0.9</inf>Ca<inf>0.1</inf>CoO<inf>2.5+δ</inf>
Miura N., Murae H., Kusaba H., Tamaki J., Sakai G., Yamazoe N.
Journal of the Electrochemical Society 146 ( 7 ) 2581 - 2586 1999.7
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of the Electrochemical Society
Oxygen permeation properties of Sr1-xA′xCoO2.5+δ (A′ = Ca, Sr, Ba, and Mg) were investigated. The oxides with x≤0.2 had hexagonal 2H-BaNiO3-type structure at room temperature. The disk membranes (1.0 mm thick) made of these oxides, when cooled from high temperature, showed significant rates of oxygen permeation down to critical temperatures characteristic of the kind of oxides, below which the rates sharply diminished. Among the oxides tested, Sr0.9Ca0.1CoO2.5+δ showed the largest rate (2.0 cm3 at standard temperature and pressure min-1 cm-2) at 900 °C. As indicated by the X-ray diffraction and thermogravimetry-differential thermal analysis, this oxide underwent phase transformation between the above structure (low-temperature phase) and a cubic perovskite structure (high-temperature phase), which were oxygen nonpermeable and oxygen permeable, respectively. On heating, the oxygen content (2.5+δ) of the oxide decreased in two steps, i.e., first from 2.75 to 2.6 over the temperature range 400 to 600 °C without changing the structure, and then from 2.6 to 2.5 at the temperature of transformation to the high-temperature phase (about 900 °C). The rate of oxygen permeation of the oxide at 900 °C was found to depend on the membrane thickness. Based on these results, oxygen permeation and its relevance to phase transformation are discussed.
DOI： 10.1149/1.1391975
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Oxygen permeability and phase transformation of Sr0.9Ca0.1CoO2.5+d Reviewed
共著者：N. Miura, H. Murae, H. Kusaba, J. Tamaki, G. Sakai, N. Yamazoe
Journal of Electrochemical Society, Vol. 146, No. 7, 2581-2586 146 ( 7 ) 2581 - 2586 1999.7
Language：English Publishing type：Research paper (scientific journal)