Preparation,Crystal Structure,Physical Properties and Electronic Band Structure of TlScQ2 (Q = S,Se and Te)

The title compounds were prepared by reaction of Tl₂Q (Q = S, Se and Te) Sc and Q in the temperature range of 200 to 500 °C. The structures of the selenide and the telluride adopt the α‐NaFeO₂ type, while TlScS₂ crystallizes in the β‐RbScO₂ type structure. The space group is for TlScSe₂ and TlScTe₂ with a = 3.9370(4) Å, c = 23.194(5) Å, and a = 4.2129(4) Å, c = 24.099(3) Å, respectively. The sulphide crystallizes in P6₃/mmc with a = 3.761(3) Å and c = 14.942(4) Å. The crystal chemical relations between the three chalcogenides are discussed. According to the electrical measurements and the band structure calculations, the compounds are semiconductors or poor metals.