Kinetic Problems with Intercalation Compounds

Abstract

What follows refers primarily to kinetic problems in layered intercalation compounds. It may be assumed that mobile electrons will be found in any molecular framework when this contains conjugated valence bond sequences [1] and that crystals of such compounds are semi-conductors [2]. Graphite may be regarded as a macromolecular limit of a homologous series of planar fused ring structures on this chemical basis and behaves as a semi-conductor with zero energy gap. Already in 1950 we had established that intercalation between the carbon hexagon layers in graphite by electron acceptor molecules such as bromine or iodine monochloride, or electron donor molecules such as potassium, greatly enhances the electrical conductivity parallel to the layers. However the high conductivity of these first synthetic metals was considered two-dimensionally. Perpendicular to the layers intercalation of electron acceptor molecules generally reduces the electrical conductivity of the parent graphite even further; a recent measurement for graphite nitrate showed a reduction of conductivity perpendicular to the layers by a factor of about 40 [3].