Papers by Author: Takashi Ogihara

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Authors: Hitoshi Aikiyo, Koji Nakane, Nobuo Ogata, Takashi Ogihara
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Authors: Takahiro Nakamura, Hajime Horikawa, Masahiro Asahara, Xing Zheng Wu, Takashi Ogihara
Abstract: TiO2 powder was synthesized hydrothermally from titanium alkoxide ethanol solution in supercritical state and obtained anatase type crystalline powder sized ca. 20 nm. Dye-sensitized solar cells were fabricated with the powders and evaluated the power generation efficiencies.
293
Authors: Koji Egawa, Takayuki Kodera, Takashi Ogihara
Abstract: Spherical C/LiFePO4 cathode materials were successfully prepared by spray pyrolysis. The saccharides such as monosaccharide and disaccharide or organic acid were used as carbon source. SEM observation showed that they had spherical morphology with particle size of about 1m. XRD analysis revealed that the olivine phase was obtained by heating at 700 °C under the atmosphere of argon/hydrogen (5 %). Electrochemical measurement revealed that the rechargeable capacity of LiFePO4 was significantly improved by the addition of carbon. The use of sucrose was most effective for the high rechargeable capacity and cycle stability.
475
Authors: Yukio Yamamoto, Takashi Ogihara
Abstract: Silver nanoparticles produced with a solid-phase thermal decomposition method were used for the preparation of a conductive paste supporting curing at low temperatures. The conducting paste was prepared by blending fine spherical silver powder and silver nanoparticles with a diameter of 20nm in order to reduce the electric resistivity of the electrodes. Although the viscosity of the conducting paste increased by about 25% after 60 days, it exhibited superior stability to dispersion in comparison to commercial paste. The electric resistivity of the electrode was of the order of 10-6Ωcm at a curing temperature of 200°C. Using this conducting paste, it is possible to print at widths of 20m. The resistivity was further reduced by 1% in the high temperature test at 120°C, by 5% in the high humidity and high temperature test, and by 5% during the thermal shock test at temperatures ranging from -45 to 80°C.
297
Authors: Takahiro Nakamura, Yoshihiro Nakatani, Takashi Ogihara, Hajime Horikawa, Masahiro Asahara
Abstract: Conductive SnO2 powder was synthesized by ultrasonic spray pyrolysis and was blended with TiO2 nano particles in order to improve the conductivity of TiO2 porous films used in dye-sensitized solar cells. However, the conductivity of the films decreased because of the exposure of SnO2 to high temperature during synthesis and calcination.
368
Authors: Koji Egawa, Izumi Mukoyama, Takayuki Kodera, Kenichi Myoujin, Takashi Ogihara
Abstract: Carbon doped LiFePO4 precursor particles were successfully prepared by spray pyrolysis. The saccharides such as monosaccharide and disaccharide or organic acid were used as carbon source. SEM observation showed that as-prepared particles had spherical morphology with narrow size distribution. XRD analysis revealed that olivine phase was obtained by heating at 700°C under the atmosphere of argon/hydrogen (5%). Electrochemical measurement revealed that the discharge capacity of LiFePO4 was improved by the addition of carbon. The addition of citric acid was most effective for the stabilization of cycle life.
81
Authors: Takayuki Kodera, Izumi Mukoyama, Kenichi Myoujin, Takanori Tsuzuki, Takashi Ogihara, Masao Uede
Abstract: LiNi1/3Co1/3Mn1/3O2 precursor powders were successfully prepared by internal combustion type spray pyrolysis. The production capacity of precursor powders was about 1 kg/h when the solution concentration was 0.5 mol/dm3. Particle size, morphology and crystal phase of LiNi1/3Co1/3Mn1/3O2 powders were characterized by XRD and SEM. XRD showed that a layered rock salt structure with a R3m space group was formed by calcination at 750 °C for 10 h. SEM showed that hollow powders with a particle size of 6 μm and irregular morphology were obtained. The discharge capacity of LiNi1/3Co1/3Mn1/3O2 was 130 mAh/g, which showed good cycle performance.
89
Authors: Kazunori Nishiwaki, Takashi Ogihara, Shigeru Motohira, Takayuki Kodera
Abstract: Spherical porous Mn2O3 powders were prepared by spray pyrolysis. Li and Al nitrate solution were immersed to porous Mn2O3 powders to obtain LiAlXMn2-XO4. Homogeneous LiAlXMn2-XO4 powders were formed by the calcination at 800°C. SEM observation showed that they had spherical morphology with particle size of about 1m. XRD revealed that the spinel phase was obtained by heating at 800°C. LiAlXMn2-XO4 cathode obtained by this method exhibited higher rechargeable capacity and cycle stability than that obtained by spray pyrolysis. The doping of Al ion was effective for the cycle stability at elevated temperature.
467
Authors: Hajime Horikawa, Takashi Ogihara, Nobuo Ogata, Masahiro Asahara, Xing Zheng Wu
Abstract: Titania nanocrystals were prepared by hydrolysis of titanium alkoxide in ethanol solution. The preparation of titania / alumina thin film was performed on ITO coated glass substrate by dip coating method using ethanol of titania nanocrystal and boemite sol. The crystal structures, microstructure and thickness of titania / alumina thin film were examined by XRD and SEM. The adsorption of dye was influenced by the surface structure of thin film. The adsorption of dye on the films was improved by the immersion into acid as HNO3. Ruthenium polypyridyl complex and triarylmethylium salt were used as dye. Electrode using titania / alumina thin film for dye-sensitized solar cell was constructed.
231
Authors: Izumi Mukoyama, Kenichi Myoujin, Takashi Ogihara, Masao Uede, Hironori Ozawa, Kazunori Ozawa
Abstract: Spherical LiAlxMn2-xO4 fine powders were continuously produced by Internal Combustion Type Spray Pyrolysis Apparatus Using Gas Burner from metal nitrate precursor solutions. XRD showed that LiAlxMn2-xO4 powders were well crystallized in a spinel structure with the Fd3m space group. As-prepared powders have a spherical particle shape with a diameter of 2.3 μm. As-prepared samples were calcined at 800  for 10 h in air. The charge/discharge capacity of LiAlxMn2-xO4 was over 100 mAh/g. A powder production capacity speed of 1 kg/h was attained by this system.
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