Crystallography and density of states calculation of MxMo6Se8 (M = Ti, Cr,Fe, Ni)

Chevrel phases have an open lattice in which cations can be inserted. These cations are generally located in cavity 1 or 2. We present here the crysta llographic structure of selenide compounds in which 3d ions are inserted. T hese cations have an original position in cavity 2. These phases should hav e low lattice thermal conductivity and are currently being investigated for thermoelectric application. Good thermoelectric materials are also semicon ducting. We present here band-structure calculations on these 3d ion Chevre l phase selenides: TiMo6Se8 is the only one found to be semiconducting. CrM o6Se8, FeMo6Se8, and NiMo6Se8 are metallic and might be magnetic. [S0163-18 29(99)15347-5].