Stability of Phases in the Cesium—Graphite System

Abstract

The thermodynamic properties of cesium—graphite lamellar compounds prepared from natural graphite flakes have been studied at 400° to 800°C. The factors which contribute to the thermodynamic properties of the compounds are discussed. The stability and structure of the stages below C₁₀Cs can be understood on the basis of a semiempirical reaction mechanism in which it is assumed that the cesium is fully ionized. The reaction mechanism considers the following parameters: the energy required to separate the carbon layers upon formation of the compounds; the density of cesium in the filled layers; the electrostatic interactions between cesium‐filled layers; and the bonding energy of cesium in the filled layers. Deviations in the heats of formation from those predicted by the model occur in the case of C₈Cs and C₁₀Cs. These deviations are attributed to the unique structure of C₈Cs and C₁₀Cs in which each carbon layer is sandwiched between two layers of cesium.