Electrical Conductivity of Graphite Bromine Lamellar Compounds

Polycrystalline graphite was allowed to react with bromine vapor, and the change of its electrical conductivity during the course of bromination and debromination was studied. The graphite was found to behave in two different ways depending on the process of bromination. When the vapor pressure of bromine was changed stepwise, following the equilibrium line of bromine absorption of graphite, the electrical conductivity showed a reversible change. On the other hand, when a graphite sample was brominated with the saturated vapor, an increase of the electrical conductivity steeper than that of the former case was observed. These results were discussed in relation to the structural analysis of the brominated graphite. A metastable phase of graphite bromide, the electrical conductivity of which remained unchanged in spite of a considerable increase of absorbed bromine, was found. The electrical conductivity of the residue compounds was also investigated, and a steep decrease was observed at high concentrations of bromine.