CHALCOGEN REARRANGEMENT IN THE CHEVREL COMPOUND INMO6SEZS8-Z AT 500-DEGREES-C

We prepared two sets of lithium insertion compounds LixMo6SezS8-z with z=4, 5, 6, 7, and 8, by removing copper chemically from Cu2.5Mo6SezS8-z, and then (1) adding lithium in electrochemical cells, or (2) preparing InMo6SezS8-z by annealing indium and Mo6SezS8-z powders at 500°C, and then replacing the indium with lithium in electrochemical cells. The variation of voltage of these electrochemical cells with x is different for the two sets, suggesting that the treatment of the second set at 500°C has modified the distribution of sulfur and selenium around the Li sites. We confirmed this change with single-crystal x-ray diffraction on Cu2.5Mo6Se4S4, Cu2.0Mo6Se4S4, Mo6Se4S4, and InMo6Se4S4. © 1990 The American Physical Society.