The Effect of Gasification on the Diamagnetism of Graphite and Artificial Carbons

Magnetic susceptibility and magnetic anisotropy measurements by the Faraday method were carried out on samples of natural graphite, graphitized carbon composites, stress recrystallized pyrolytic graphite and on a graphitized carbon black (Graphon). The total susceptibility at room temperature ranged from − 18.75 × 10−6 emu/g for graphon to −21.68 × 10−6 emu/g for the stress recrystallized pyrolytic graphite. The anisotropy ratios (R = χ⊥/χ∥) ranged from 1.02 for an extruded lampblack based carbon composite to 40 for the stress recrystallized sample. The temperature dependence of the susceptibility can be accounted for using a two dimensional degenerate electron gas model. From this model the values of To, the degeneracy temperature of the electron gas, the number of effective electrons per carbon atom and α = m/m*, the ratio of the electron rest mass to its effective mass were obtained. Within the spirit and limitations of this model the following estimates for To were obtained; 344°K for natural graphite...