GRAPHITIZATION BEHAVIOR OF CARBON-FILM PREPARED FROM HIGH-MODULUS POLYIMIDE FILM - SYNTHESIS OF HIGH-QUALITY GRAPHITE FILM

Graphite films comparable with highly oriented pyrolytic graphites in quality have successfully been prepared without any pressurization during the heat treatment. Graphitization behavior in carbon films prepared from a 45-mum-thick, high-modulus polyimide film, prepared via polyamic acid gel, with heat treatment temperatures between 1800 and 3200-degrees-C, was investigated by measuring interlayer spacing d002, mosaic spread, ratio of the resistivity at room temperature to that at liquid nitrogen temperature, and magnetoresistance at liquid nitrogen temperature. Carbon layers are oriented well in all the specimens examined. Graphitization was initiated by the heat treatment around 2200-degrees-C. Metallic-like temperature dependence of the resistivity was observed for the specimens heat-treated between 2900 and 3200-degrees-C. For these specimens, ratio of the resistivity at room temperature to that at liquid helium temperature was found to be higher than 1.68. For the 3200-degrees-C-treated specimen, the interlayer spacing, mosaic spread, maximum transverse magnetoresistance in a field of 1 T at liquid nitrogen temperature, resistivity ratio at room temperature to that at liquid helium temperature are 0.3354 nm, 5.0-degrees, 1205.6%, and 3.46, respectively.