INTERCALATION OF ALCL3 INTO FECL3-GRAPHITE INTERCALATION COMPOUNDS AND OCCURRENCE OF BIINTERCALATION

The formation process of the ternary AlCl3-FeCl3-graphite intercalation compounds (GICs) was studied by using three different reaction paths at 150-degrees-C. In the reaction of stage 1, FeCl3-GICs with AlCl3, the exchange of intercalated FeCl3 for AlCl3 occurred and, consequently, the formation of the ''mixed''-type ternary GIC was observed at the edge of the flakes. The reaction of stage 2 FeCl3-GIC with AlCl3, however, gave the ''bi-intercalation''-type GIC due to intercalation of AlCl3 into unoccupied graphite galleries. In the reaction of the host graphite with an equimolar mixture of AlCl3 and FeCl3 the preferential intercalation of AlCl3 was observed in the beginning of the reaction, and then the exchange of AlCl3 for FeCl3 in the stage 1 compound occurred: Through the determination of the charge density distribution and the structural refinement by a pattern-fitting technique on mixed- and bi-intercalation-type GICs, the former was found to have more defective intercalate layers than the latter.