THE CRYSTAL-STRUCTURE OF TICU5SE3

The crystal structure of copper-deficient TlCu5Se3 has been refined from single-crystal X-ray diffraction data. The previously suggested new structure type was confirmed with agreement factors RF = 0.033 and RwF = 0.035. The symmetry is tetragonal, space group P42 mnm (136). For the investigated composition, TlCu4.8Se3, the cell dimensions are a = 12.900 and c = 3.968 Å (Z = 4). The structure has features common to other thallium copper chalcogenides such as TlCu3Se2 and TlCu7Se4. Similarities to some multinary alkali metal oxide structures are emphasized. © 1990.