An electron microscopic study on the turbostratic carbon formed in phenolic resin carbon by catalytic action of finely dispersed nickel

Very fine particles of certain substances are known to promote the catalytic graphitization of carbonaceous material, resulting in a unique carbon whose X-ray parameters, lying in the range of turbostratic carbon, remain almost unchanged even after more severe heat-treatments. To elucidate the actual structure of this type of carbon, its formation mechanism, and the reason for its high thermal-stability, a high resolution electron microscopic investigation was carried out on carbons derived from phenolic resin lightly and heavily doped with an organo-nickel compound. The electron microscopic texture of this carbon was found to consist of entangled lattice fringes of a stack number comparable with its X-ray L_c-value (110 Å). This texture was analogous to that of some types of the hard carbon heated to very high temperatures, but the former was less sinuous in its lattice fringe and more open in its structure. The formation mechanism appeared to differ from that accepted for conventional nickel-catalyzed graphitization, and to be particularly related with nickel particles in a certain size range. The evidence obtained so far was not enough to suggest a new mechanism, but only to illustrate part of some of the possible, hitherto little known mechanisms which might proceed along with it. Thermal stability of the carbon was understood to be due to its structure being similar to the hard carbon, but the ultimate reason why this type of structure was thermally stable could be made clear only to a limited extent.