Study of the phase diagrams of graphite intercalation compounds

The model of staging recently proposed by Millman and Kirczenow is used to survey the possible phase diagrams for graphite intercalation compounds. For a wide variety of intercalants, including the alkali metals and aromatic molecules, the model predicts the staged structures which are observed experimentally. The model also provides physical guidelines for identifying materials in which more complex structures, such as those predicted recently by Safran, may be realized at high temperatures. We suggest a class of compounds, the transition-metal chlorides, which may possibly meet these physical guidelines. If this complex staging is found, the model predicts rich and varied phase diagrams which are very sensitive to changes in the physical parameters. We also discuss some possible improvements to the model and show that the essential predictions of the model are not affected by these improvements. © 1983 The American Physical Society.