TANSO
Online ISSN : 1884-5495
Print ISSN : 0371-5345
ISSN-L : 0371-5345
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Volume 1971, Issue 66
Displaying 1-6 of 6 articles from this issue
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  • Multi-phase Graphitization Process of Charcoal
    Michio INAGAKI, Kan-ichi KAMIYA
    1971 Volume 1971 Issue 66 Pages 76-80
    Published: August 31, 1971
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.7209/tanso.1971.76
    JOURNAL FREE ACCESS
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    Charcoal has been known to show mdlti-phase graphitization in a wide range of temperature of heat treatment. In the present work, a charcoal was heat-treated at various temperatures of 1500-3400°C for 15 min in an Acheson-type furnace and its composite profile of (002) diffraction line was separated into component profiles. The composite profile of the charcoal was concluded to consist of three component profiles; a broad band with a larger c0 -spacing than 6 .86Å, and two sharp peaks with the c0 -spacings of ca . 6.86 and ca. 6.73Å, respectively. Two components corresponded to two sharp peaks were assumed to have turbostratic and graphitic structures and so named the components T and G, respectively . However, the structure corresponded to the broad band (named the component B) was not known. At low temperature of heat treatment, the component B was major and its structure seemed to change to that of the component T gradually with the increase in temperature. Above 2400°C, the graphitic component G became the major one.
    By comparison of the present results to the results on other hard carbons and on the soft carbons under high pressure, the structure of hard carbon might be assumed that small particles of anisotropic structure are dispersed in a matrix of isotropic structure. At high temperature, anisotropic thermal expansion of the small particles may seem to be constraint by the isotropic matrix so that stress may concentrate at the small particles and abrupt structural change to graphitic structure (multi-phase graphitization) may occur.
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  • Electrical Conduction in Graphite along c Axis
    Yoshihiro HISHIYAMA, Masaaki HASHIMOTO, Akio ONO
    1971 Volume 1971 Issue 66 Pages 80-88
    Published: August 31, 1971
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.7209/tanso.1971.80
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    A study of the electrical conduction in the c-direction of graphite has been made of some pyrolytic carbons and two kinds of highly-orientated pyrolytic graphite through the measurements of galvanomagnetic effects at 77°K. Since anything that disturbs the perfect alignment of graphitic planes, like mosaic structure, will lead to a zigzag flow and decrease in the resistivity along c axis, experiments were based on the following expectations for the presence of electron transport along c axis;
    1. Magretoresistance under a constant magnetic field should not indicate a large maximum when the field is perpendicular to the layer plane.
    2, Hall voltage becomes observable only if the cyclotron motion of carriers takes place so as to pass through several layers.
    The field dependence of magnetoresistance was investigated with changing a parameter θ, the angle between the magnetic field and the axis normal to the deposition plane . All the pyrolytic carbon specimens exhibited negative magnetoresistance, while it was positive forthe pyrolytic graphites. In both cases, the maximum absolute value of magnetoresistance was found when the field direction coincided with the normal axis (;θ=0, longitudinal situation).Change of this longitudinal magnetoresistance with graphitization is nearly the same as those found for the inplane transverse magnetoresistance of usual soft carbons. Hall voltages were never detectable for each specimen except for the specimen of the most highly-orientated pyrolytic graphite, for one could not cut out a specimen of sufficient size for the measurements of Hallcoefficient from it. However, one can reasonably conclude that the Hall voltages in the plane perpendicular to the layer plane is never detectable for the specimen which has anything that disturbs the perfect alignment of the layer planes. Based on these observations, the electron transport found in the present experiments is concluded to take place only in the layer planes. The resistivity in the c-direction has been estimated to be of the order of 103 Ω cm from the acuracy of the magnetoresistance measurements. On the other hand, unusual field dependence of the magnetoresistance has been observed for the most highly-orientated pyrolytic graphite specimen in the high field region.
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  • [title in Japanese]
    [in Japanese]
    1971 Volume 1971 Issue 66 Pages 89-98
    Published: August 31, 1971
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.7209/tanso.1971.89
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  • [title in Japanese]
    [in Japanese]
    1971 Volume 1971 Issue 66 Pages 99-106
    Published: August 31, 1971
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.7209/tanso.1971.99
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  • [title in Japanese]
    [in Japanese]
    1971 Volume 1971 Issue 66 Pages 107-115
    Published: August 31, 1971
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.7209/tanso.1971.107
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  • [title in Japanese]
    1971 Volume 1971 Issue 66 Pages 116-118
    Published: August 31, 1971
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.7209/tanso.1971.116
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