INTERCALATION OF FECL3 INTO GRAPHITE FILMS IN MOLTEN-SALTS

The intercalation of FeCl3 into graphite films using the FeCl3-KCl molten salt system was studied and compared to the intercalation from the vapor phase of FeCl3. The intercalation in the molten salt proceeded gradually by changing the stage structure, in contrast to that in vapor phase where initially a stage-1 compound was formed in coexistence with unreacted graphite. The composition of the molten salt (FeCl3/KCl ratio) and the addition of chlorine gas were found to affect strongly the intercalation rate and equilibrium stage structure. An exfoliation of the graphite film occurred after intercalation in the molten salts at high temperatures (above 400-degrees-C) and produced electrical conductivities much lower than the pristine films. The intercalated films synthesized at 300-degrees-C have conductivities about four times higher than the pristine films. From these experimental results, the diffusion rate of FeCl3 into the graphite galleries is found to be faster in the molten salts than from the vapor phase and to depend on the composition of the molten salts.