Conduction mechanism in graphite intercalated with certain acceptors

Abstract

There are a number of problems which must be resolved before it can be said that the mechanism of conduction in acceptor compounds of graphite is understood. In this paper attention will be paid to compounds prepared from AsF 5, SbF 5, and FeCl 3 which exhibit very high conductivities, comparable with that of copper. An analysis of recent data on the temperature dependence of the resistivity and the magnetoresistance will be given and discussed in terms of recent models of the dispersion relationship developed by Blinowski et al. The consequences of screening and the concept of a sandwich model for the conductivity will be examined. Specific values for carrier densities, mobilities, effective masses, Fermi speed, and density of states, will be computed from the models discussed and compared with other data, such as oscillatory phenomena due to magnetic quantization (de Haas-van Alphen, Shubinkov-de Haas, magnetothermal oscillations), magnetic susceptibility, etc. Using these estimates, a discussion will be developed of the effect of crystal defects on the electrical conductivity. Scattering on grain boundaries and effects of crystal misalignment will be considered, since practical synthetic conductors will be based on materials with these defects. The possibility of making inexpensive synthetic conductors will be considered within this context.