Quaternary chalcogenides of formula MII2MV2−2yM′2yS6 and Se6

Compositions of the title formula where M^II = Ba and Sr, M^V = Ta and Nb, M′ = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rh and Ir, and y = 0.5 and 0.33 were prepared by two methods: reaction of the elements in evacuated silica tubes and reaction of M^IICO₃, M^V₂O₅, and M′ oxides with H₂S. When M^II = Ba, all members have the BaNiO₃ structure. When M′ = Mn and Cu, structural distortions are present. Some compositions have Ta or S vacancies. When M^II = Sr, compositions were prepared only with Ta, for y = 0.5 and when M′ = Cr and Fe. Electrical measurements on selected compositions showed semiconductivity.