Crystal structure of Co6Te5O16

The crystal structure of Co6Te5O16, formerly described as Co4Te3O10, was investigated. Its orthorhombic, pseudohexagonal cell (a = 11.032, b = 10.295, c = 12.876 A, space group Pnma-Dsub(2h)sup(16), Z = 4) contains four independent Te atoms, three of them forming pyramidal TeO3 groups, with oxygen atoms at longer distances (>2.5 A) enlarging the coordination numbers to (3+1), (3+2), and (3+3) resp. The fourth Te atom is four-fold coordinated. Three independent Co atoms are surrounded by (5+1), 6, and (6+1) oxygen atoms in arrangements of low symmetry. Indexed X-ray powder data of Mn6Te5O16 and Mg6Te5O16 are given. (author)