Positional and orientational correlations in the graphite intercalate C24Cs

An x-ray study of the Cs layers in C24Cs is presented. The Cs layer has a uniform 2-d liquidlike structure at 300 K not in registry with the graphite layers. A crossover to 3-d interlayer correlation is observed at 165 K. Single-crystal measurements show that the Cs layers rotate relative to the graphite 100 directions. An orientational ordering between two positionally disordered phases occurs at 228 K and a new transition to a mixed registered phase at 50 K is reported. © 1979 The American Physical Society.