In situx-ray investigation of stage transformations in potassium-graphite intercalation compounds

We have studied stage transformations and growth kinetics of potassium-graphite intercalation compounds by x-ray ($00l$) scans. The samples were prepared in situ in a high-temperature two-zone x-ray furnace. In the transition regions of stages 1 ↔ 2, 4 ↔ 5, and 6 ↔ 7, two distinct stages coexist and all Bragg reflections exhibit resolution-limited widths. This implies that the stage transformation is a direct process with no need of forming intermediate structures. The kinetics of the transformation indicate that the staging process is nucleation rather than diffusion controlled.