ON THE CRYSTAL-CHEMISTRY OF THE COPPER(II ) ZINC TELLURATES CU5ZN4TE3O18 AND CU1.5ZN1.5TEO6 WITH A NOTE ON CU1.5CO1.5TEO6

Single crystals of Cu5Zn4Te3O18 (I), Cu1.5Zn1.5TeO6 (II) and Cu1.5Co1. 5TeO6 (III) have been prepared and investigated by X-ray work. The str ucture of (I) was solved in the monoclinic space group C-2(3)-C2, a = 14.834(2), b = 8.801(1), c = 10.375(2) Angstrom, beta = 93.27(2)degree s, Z = 4. (II) and (III) crystallize with cubic symmetry, space group T-h(7)-Ia (3) over bar, a((II)) = 9.557(1), a(III), = 9.570(1) Angstro m, Z = 8. (I) shows a complicated structure formed by TeO6 octahedra i solated from each other, Zn2O6 double tetrahedra and Zn2O8 double squa re pyramids. These polyhedra are incorporated into a network of edge a nd corner connected stretched CuO6 octahedra. (II) and (III) are isoty pic or Cu3TeO6 and have a (Cu/M)(3)O-6 octahedra network, statisticall y occupied by Cu2+ and Zn2+ or Cu2+ and Co2+.