Transition-metal dichalcogenides from disintercalation processes. Crystal structure determination and Mossbauer study of Li2FeS2and its disintercalates LixFeS2(0.2⩽x⩽2)

In agreement with its hexagonal subcell parameters (a=b=3.908(2) AA and c=6.279(4) AA) and c/a ratio of 1.601, the Li2FeS2 structure was found to be constructed from a hexagonal close packing of S2- anions with tetrahedral iron ions. Different filling of the two (FeS4) sites was found to be responsible for the 2a*2b*c supercell. Lithium ions are scattered on tetrahedral and octahedral sites, some of the latter remaining empty because of intercationic Coulombic repulsions. Mossbauer study of LixFeS2 disintercalates (0.2