Graphite Intercalation Compounds-General Properties

Abstract

Graphite intercalation compounds are formed by the insertion of atomic or molecular layers of a different chemical species between layers in a graphite host material. The intercalation process occurs in highly anisotropic layered structures where the intraplanar binding forces are large in comparison with the inter-planar binding forces. Some examples of host materials for intercalation compounds are graphite, transition metal dichalcogenides, some silicates, and metal chlorides. Of the various types of intercalation compounds, the graphite compounds are of particular physical interest because of their high degree of structural ordering. Most celebrated among the ordering characteristics of the graphite intercalation compounds is the staging phenomenon, whereby the intercalate layers are periodically arranged in the matrix of graphite layers and are characterized by a stage index n, denoting the number of graphite layers between adjacent intercalation layers, as is illustrated in Fig. 1. This staging phenomenon occurs for all graphite intercalation compounds even in very dilute concentrations (n ∿ 10).