Long range ordering in the graphite intercalation compounds

Graphite surfaces treated with NaOH, LaCl3 and CeCl3 aqueous solutions were studied by scanning tunneling microscopy. These metals in the compounds are known to have poor lattice matching with graphite. In the presence of low densities of intercalants, which are not enough to form a stage structure, the existence of large periodic superstructures was confirmed. Since the observed structures could not be interpreted by Moiré pattern hypothesis, they might be directly related to the intercalant arrangement. The obtained results directly show the importance of long-range interactions for the understanding of the graphite intercalation compound structures as predicted by theoretical studies.