ANISOTROPIC ELECTRICAL-CONDUCTION IN RELATION TO THE STACKING DISORDER IN GRAPHITE

The in-plane and c-axis conduction behaviors of kish graphite and of hot-worked pyrolytic graphite are discussed in relation to their structural perfection, special interest being focused onto the stacking fault disorder which appears in the form of extended basal dislocation ribbons. Analysis of the two-dimensional magneto-conductivity indicates that the carrier density of faulted specimens increases slowly with temperature (T) even below the degeneracy point of the carrier system, whereas the unfaulted ones do not. The c-axis resistivity (ρ{variant}c) has been found to decrease with diminishing stacking disorder for a well-defined specimen group not containing such irregularities as microcracks. This verifies the applicability of the band model to the intrinsic ρ{variant}c's, in connection with the success of Ono's theory accounting for the wide-range scattering of past data. The discrepancy still remaining between the theoretical and experimental ρ{variant}c vs T relationships; as well as the increase of the in-plane conduction carriers density with temperature, seems to be removed by assuming thermal liberation of the localized Tamm-state electrons from the stacking fault planes. © 1979.