Electronic properties, resistive anomalies, and phase transitions in the graphite intercalation compounds with K, Rb, and Cs

Overall resistivity-temperature data for the graphite intercalation compounds of potassium, rubidium, and cesium at stages 1 and 2, and of potassium at stages 3 and 4, at room temperature and below are presented. Except in the stage 1 compounds two resistivity anomalies are observed for each compound between 77 and 300 K. Correlation with known structural studies suggests the anomalies are due to interplanar and intraplanar ordering within the intercalant layers upon cooling and this conclusion is shown to be qualitatively consistent with the temperature dependence of the Hall coefficient and magnetoresistance of KC₂₄ through the anomalies, which can be explained in terms of carrier mobility rather than carrier density changes. It is suggested that the details of the ordering process may be unique in each compound.