In this paper we address the mechanism of intercalation of commensurate metal-graphite intercalation compounds and its consequences on the structural properties of the synthesized materials. Using the case of ${\text{KC}}_8$ which crystallizes in the orthorhombic system ($Fddd$ space group) and consequently does not possess any hexagonal or rhombohedral symmetries, it has been possible to show that a ${\text{KC}}_8$ sample prepared from a natural graphite single crystal however exhibits experimentally an hexagonal symmetry. This apparent irrational observation is fully explained in this paper by the intercalation process itself so that after intercalation the compound is no more a single crystal. This result is extended to the cases of all the first stage metal-graphite intercalation compounds.

• Received 8 November 2009

DOI:https://doi.org/10.1103/PhysRevB.81.155425