Preparation, characterization and intercalation of ternary chalcogenides with layered composite crystal structures formed in the Bi-Ta-S and Bi-Ta-Se systems

摘要

Two kinds of chalcogenides with layered composite crystal structures have been formed in Bi-Ta-S and Bi-Ta-Se systems depending on the preparation conditions: (BiS)_(1.08)TaS_2 and (BiS)_(1.08)(TaS_2)_2 for the former system and (BiSe)_(1.09)TaSe_2 and a new selenide (BiSe)_(1.09)(TaSe_2)_2 for the latter. The new chalcogenide has been characterized by powder X-ray diffraction and electron diffraction. The atomic coordinates in the layer-stacking direction of the new chalcogenide and its hydrazine intercalation compound have been determined. The electrical resistivity measurement has suggested that all of these chalcogenides are low temperature superconductors.