C-Axis Electrical Conductivity of Graphite

Abstract

Small crystals of natural graphite showing no evidence of twinning were found in a sample of marble from the Lead Hill mine (Ticonderoga, New York). They were isolated, handled very carefully to avoid deformation, and their $c$-axis conductivity determined. It was found to be about 2×${10}^2$ ${\mathrm{}\left(\mathrm{ohm}\mathrm{cm}\right)\mathrm{}}^{-1\mathrm{}}$, in accord with previous measurements of less perfect crystals. It is shown that much of the variability in the measurements of larger, less perfect crystals is caused by nonuniform current flow. However, evidence is adduced to indicate that the actual $c$-axis conductivity of natural graphite crystals does vary somewhat.