Journal of Advanced Science

Cation ratio of Na-Co system oxides formed in calcination process and thermoelectric properties

Yuichi IMAGAWA, Kazuo UEMATSU

2002 Volume 14 Issue 3 Pages 105-109
Published: 2002
Released on J-STAGE: February 25, 2010

DOIhttps://doi.org/10.2978/jsas.14.105

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The products of Na-Co-system oxides were prepared using Na₂CO₃, Co₃O₄ and other ingredient powders by calcination process. Particular interest is dedicated to the composition of the powder crystals as been formed by the calcination process. It has been found that the composition of the powder crystals always results in Na_xCo₂O_y crystals regardless of the nominal composition, where x is a little above 1.3. For calcination powders of other concentrations, Na-oxides or Co-oxides have been found to remain as contamination, which then cause a decrease in thermoelectric performance.

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Improvement of growth activity of microbes in tea field soil by organic fertilizer

Yasutaka SUEHIRO, Kunimasa KOGA, Kei KAMINO

2002 Volume 14 Issue 3 Pages 110-114
Published: 2002
Released on J-STAGE: February 25, 2010

DOIhttps://doi.org/10.2978/jsas.14.110

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From the view of point of productivity and quality of tea leaf, improvements of the microbial growth activity with degradation of organic matters in tea field soil have been expected. In the present study, the analysis and bacterial community profile of tea field soil treated with organic fertilizer versus compound fertilizer in the same farm in Shizuoka were evaluated. Usage of organic fertilizer improved acidity and water holding capacity of the soil in tea field and changed conditions of soil in tea field to be suitable for microbial viability and as result changed bacterial community profiles. Using microbial calorimetry, growth activity of microbes in tea field soil with degradation of organic matters increased as much as 1.2 times higher compared with that of compound fertilizer.

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Effect of zinc chloride for rapid migration of Si in pack siliconizing of copper

Kuniyasu GEMMA, Kenji KITAJIMA, Kaoru YOSHIDA, Mamoru KAWAKAMI

2002 Volume 14 Issue 3 Pages 115-124
Published: 2002
Released on J-STAGE: February 25, 2010

DOIhttps://doi.org/10.2978/jsas.14.115

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In a pack siliconizing of copper, ZnCl₂ as an activator showed a peculiar effect to form a thick multi-diffusion layer composed of two diffusion elements of Zn and Si. The Zn was always detected at the edge of the layer and the Si was also detected at just behind the edge. Thus a parallel diffusion of Zn and Si was observed in the siliconizing. The depth of the Si in copper was estimated approximate 50 times than that calculated from the diffusion constant of Si at the same temperature. The diffused Zn was supplied as vapor generated by reaction between ZnCl₂ and ferrosilicon powder. EPMA profile of the layer showed that diffusion of the Si attended the diffusion of the Zn. At 773K the layer of β phase (BCC) was formed with mechanism of linear growth, and α phase (FCC) of the layer was formed at 873K with parabolically. NH₄ Cl as activator was hardly formed diffusion layer in the copper.

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Ultra-high-temperature and ultra-low-oxygen atmosphere controlled furnace for development of materials technology

Susumu TAKAHASHI, Kiichi KANDA

2002 Volume 14 Issue 3 Pages 125-130
Published: 2002
Released on J-STAGE: February 25, 2010

DOIhttps://doi.org/10.2978/jsas.14.125

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Metallurgical processing at 2600°C is developed under a special clean N₂ or Ar atmosphere in a new type of continuous open furnace. The furnace can be used for sintering of various non-oxide ceramics, and diffusion bonding between alloys and ceramics, furthermore between various high temperature materials with no use of flux and without high compressed condition such as HIP technology. The novel technology at thus ultra high temperature depends on development of C/C composite conveyor belt. Many metal oxides (for example SiO₂, TiO₂) are dissociated to metal and oxygen in the atmosphere kept under an ultra low oxygen pressure. The principle is different from the case of the hydrogen reduction of oxides as known commonly. Thus there are no explosion such a hydrogen. Therefore higher safety is warranted in spite of open furnace. The great advantage yield is an inline system that heat treating process put among industrial machining line.

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Study on crystal growth, electrical and optical properties of ITO (Indium Tin Oxide)

Masayasu KOYAMA, Moriaki WAKAKI, Thomas MASON, Gabriela B. GONZALEZ

2002 Volume 14 Issue 3 Pages 131-132
Published: 2002
Released on J-STAGE: February 25, 2010

DOIhttps://doi.org/10.2978/jsas.14.131

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The demand for the transparent conductors or semi-conductors in the visible region, which have good transparency and electric conductivity, is increasing with the development of electro-optical devices. Recently, ITO films with main element of In₂O₃ doped with low concentration of SnO₂ have been prepared. However, there are few reports about the single crystal of In₂O₃- SnO₂ (ITO). The aim of this study is to know the defect structure minutely, which is typical in these oxide materials. ITO single crystals were prepared by the flux method. The structure was characterized by X-ray diffraction analysis, and free carriers were evaluated through the dispersion analysis of far-infrared reflection spectra.

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[title in Japanese]

[in Japanese]

2002 Volume 14 Issue 3 Pages 133-138
Published: 2002
Released on J-STAGE: February 25, 2010

DOIhttps://doi.org/10.2978/jsas.14.133

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