Stage Transformation and Staging Disorder in Graphite Intercalation Compounds

Stage purity and staging transitions of potassium-graphite intercalation compounds have been investigated in situ by high-resolution x-ray scattering. The positions and profiles of ($00L$) Bragg reflections indicate staging disorder in thermal equilibrium for all compounds larger than stage 2, which increases with increasing stage number. The transition region between stages exhibits a miscibility gap for stage mixing whose size decreases with higher stages. The results are compared with recent theories on the staging of graphite intercalation compounds.