Electrical Conductivity of Single Crystals of Graphite

Abstract

The electrical conductivities along the principal directions of graphite crystals have been measured using a large number of well-developed single crystals obtained from Ceylon. The conductivity along a direction perpendicular to the hexagonal axis is about ${10}^4$ times that along the axis. Rectification and other nonlinear effects are totally absent. Thickness plays an important part in the determination of the conductivity normal to the hexagonal axis and attempts have been made to avoid this difficulty. These measurements have been extended to temperatures between 80°K and 500°K. The conductivity perpendicular to the hexagonal axis falls roughly exponentially with rising temperature and that along the axis rises similarly with temperature. A magnetic field has been found to cause a decrease in both the conductivities—the effect on the conductivity normal to the hexagonal axis being more pronounced. This decrement falls roughly exponentially with rising temperature and has a tendency to attain a steady value at higher temperatures.