Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 57, Issue 11
November
Displaying 1-11 of 11 articles from this issue
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  • Synthesis of CuO Powder by Homogeneous Precipitation Process under Microwave Irradiation
    Yoshitaka Ino, Masakuni Ozawa, Ryoji Katoh, Akira Kagohashi
    2010 Volume 57 Issue 11 Pages 695-698
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.695
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    We investigated the morphology of CuO powders synthesized by three processes: homogeneous precipitation, homogeneous precipitation under microwave irradiation, and heat treatment of precursor at 600°C. Homogeneous precipitation process was applied to a mixed aqueous solution of copper precursor complex, which was obtained from cupper nitrate and hexamethylenetetramine. The 2.45 GHz microwave irradiation to a precursor solution induced the formation of CuO powders with special morphology at 95°C in aqueous solution. Also the rapid formation of CuO from precursor by microwave was revealed in comparison with the processes without microwave irradiation.
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Special Issue: Functional Materials Design in Highly-Ordered Assembly Systems
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  • Synthesis of Ba3Ta6Si4O26 using Aqueous Solution Processes and Its Photocatalytic Activity
    Ryotaro Yanagisawa, Valery Petrykin, Masato Kakihana
    2010 Volume 57 Issue 11 Pages 701-705
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.701
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    A single phase of Ba3Ta6Si4O26 consisting of one-dimensional TaO6 chains has been synthesized by an amorphous metal complex (AMC) method employing water soluble materials, tantalum peroxolactate and silicon tetrapropyleneglycoxide. In contrast, a polymerizable complex method of another solution process gave a mixed phase of Ba3Ta6Si4O26 and orthorhombic BaTa2O6. It has been suggested that homogeneity of the precursors strongly affected the phase purity. Ba3Ta6Si4O26 produced hydrogen and oxygen from water under ultraviolet irradiation. Thus, the present research revealed that Ba3Ta6Si4O26 is an active photocatalyst for water splitting. Ba3Ta6Si4O26 prepared by the AMC method showed higher activity than that prepared by a solid state reaction.
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  • Low Temperature Synthesis of (Ca, Ce)3Sc2Si3O12 Phosphor by Hydrothermal Gelation Method Using Novel Water Soluble Silicon Compound
    Taichi Yamaguchi, Yoshihito Suzuki, Masato Kakihana
    2010 Volume 57 Issue 11 Pages 706-710
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.706
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    Low temperature synthesis of a (Ca, Ce)3Sc2Si3O12 (CSS) phosphor with a garnet structure has been achieved by a hydrothermal gelation (HTG) method using a water soluble silicon compound. The CSS phase was obtained by calcining a hydrothermally driven gelations matter at 1073 K in the HTG method while synthesis of CSS by a solid state reaction required the calcinations at higher temperature than 1673 K. The low temperature synthesis of CSS stands on the homogeneity of the metallic components in a gel obtained from a homogeneous aqueous solution of starting materials by hydrothermal treatment at 473 K. It was revealed from investigation of the hydrothermal conditions that the homogeneity of the gels was independent of the concentration of components and the time of hydrothermal treatment but dependent on temperature because the temperature affected the rate of the gel formation.
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  • Development of Novel SiC/CBC (Ceramic Bonded Carbon) with 3D Micro-network Structure
    Masaharu Nakamura, Yoshinari Miyamoto, Tetsuro Tojo
    2010 Volume 57 Issue 11 Pages 711-715
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.711
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    A new SiC coating on carbon particles has been developed using SiO powders as the Si source by a chemical vapor reaction. Uniform SiC coating was obtained on individual particle with the thickness of 10 nm to 10 μm. The SiC coated carbon particles sintered by PECS exhibited unique microstructures with a 3D micro-network structure consisting of graphite grains covered with thin SiC grain boundaries. The sintered products at 2000°C showed a high bending strength of 150 MPa.
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  • Magnetoelectric Effect in Multiferroic CoFe2O4-BaTiO3 Composites
    Haruka Tada, Kenji Kamishima, Koichi Kakizaki, Masamichi Sakai, Nobuyu ...
    2010 Volume 57 Issue 11 Pages 716-721
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.716
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    Co1-xFe2+xO4-2BaTiO3 (x=0, 0.1 and 0.2) samples were prepared by using a conventional ceramic method. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements were done on these samples and we confirmed that cobalt ferrite and BaTiO3 components were clearly separated in the composites. The samples exhibited both ferroelectric and ferromagnetic properties. This indicates the samples were multiferroic materials. The resistivity was increased with x, whereas the tetragonality of BaTiO3 was decreased with x. While a sample with x=0.1 had the highest permittivity of 522, samples with x=0 and 0.2 had lower permittivity, which may have been caused by leakage current and deterioration of the ferroelectricity of BaTiO3, respectively. This same sample with x=0.1 also exhibited the highest ME coefficient of 0.2 mV/cm Oe. We expect that improved permittivity will lead to a higher ME coefficient.
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Special Issue: Future Materials for Advanced Batteries
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  • Open Circuit Voltage of LixFePO4 Olivine Cathode and Its Electrochemical Reaction
    Tatsuya Nakamura, Hiroki Matsui, Yoshihiro Yamada, Mitsuharu Tabuchi, ...
    2010 Volume 57 Issue 11 Pages 725-728
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.725
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    Cathode using the olivine particles was subjected to an open-circuit voltage measurement under the relaxation condition of 24 h at each SOC and DOD states. The electrochemical reaction in the LiFePO4 cathode was composed of a large plateau around 3.45 V with sloped regions nearby for both the fully charged and discharged states. It was found that the potential profile in the sloped regions exhibited a hysteresis. Furthermore, both sloped regions became narrower when the operating temperature was raised from 30 to 60°C. Furthermore, it was found that the apparent diffusion coefficient of Li+ ions in the sloped regions was much smaller than that in the plateau region. These facts implied that the obtained profiles were not in an equilibrium state with a quasi-OCV profile than the real one, and that the potential relaxation in the sloped regions took an extremely long time.
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  • Synthesis of LiFePO4/C Composite Particles by Gas-Solid Phase Reaction and Their Electrochemical Properties
    Yuya Shima, Tatsuya Nakamura, Hiroki Matsui, Yoshihiro Yamada, Hironar ...
    2010 Volume 57 Issue 11 Pages 729-733
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.729
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    LiFePO4/C composite particles were prepared by gas-solid phase reaction. The reaction temperature had a detrimental effect on the purity of the composite particles. The suitable temperature was around 650°C, above and below which ferromagnetic impurities were found. The retention time influenced only the carbon deposition amount, but the excess amount of carbon caused the degradation of the electrochemical performance. The specimen prepared at the optimum conditions exhibited superior performances in both rate capability and cycle stability as well as less impedance growth during the cycling.
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  • The Development of Novel Si/C Composite with Carbon Nanofiber for Lithium Ion Batteries
    Qin Si, Kazuma Hanai, Atsushi Hirano, Nobuyuki Imanishi, Osamu Yamamot ...
    2010 Volume 57 Issue 11 Pages 734-740
    Published: 2010
    Released on J-STAGE: December 14, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.734
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    The electrochemical performance of a composite of nano-Si powder and a pyrolytic carbon of polyvinyl chloride (PVC) with a carbon nanofiber (CNF) was examined as an anode for lithium ion batteries. CNF was incorporated into the composite by two methods; mixing of CNF, nano-Si powder, and PVC with subsequent firing (Si/CNF/C) and direct mixing of CNF with the nano-Si coated with carbon produced by pyrolysis of PVC (Si/C@CNF). The external BET surface area of Si/C@CNF was comparable to that of Si/CNF/C. The micropore BET surface area of Si/CNF/C (73.86 m2 g-1) was extremely higher than that of Si/C@CNF (0.74 m2 g-1). The composites prepared by both methods exhibited high capacity and excellent cycling stability for lithium insertion and extraction. A capacity of more than 700 mAh g-1 was maintained after 30 cycles. The coulombic efficiency of the first cycle for Si/C@CNF was as low as 53 %, compared with the 71 % for Si/CNF/C. A composite electrode prepared by mixing Si/CNF/C and CNF exhibited a high reversible capacity at high rate, excellent cycling performance.
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