LixCuyMo6Se8: phase behaviour and electrochemistry

The authors present electrochemical and in situ X-ray diffraction results on the pseudoternary system Li x Cu y Mo 6 Se 8 for 0 1 and X+y approaches 4, irreversible phase separation is observed. An unidentified Cu-rich phase then coexists with the remaining Cu-deficient Chevrel phase, even after subsequent removal of Li. They prepared this Cu-rich phase by intercalating Cu into a Cu/Cu y Mo 6 Se 8 cell but could not index the Bragg peaks. Because of the irreversible nature of this system, they present only a partial pseudo-ternary phase diagram.