The Structure of Thorium(IV) Dititanium(IV) Oxide, ThTi206

The crystal structure of a modification of ThTbOG, obtained from the melt at 1100 °C, has been analysed by X-ray diffraction and refined to the R value of 0.051. The crystals are monoclinic with a= 1.0799(7), b = 0.8570(6), c = 0.5192(3) nm and p = 115.29(3)0 , space group C2/c, Z = 4, F(OOO) = 728. The structure is based on a near-hexagonal close-packing of the oxygen atoms, with the thorium and titanium atoms in »octahedral sites«. The coordination polyhedron of Th is a distorted square antiprism with Th-0 distances from 0.232 to 0.265 nm, that of Ti a distorted octahedron with Ti-0 distances from 0.187 to 0.201 nm like those characteristic for Ti02 polymorphs. The Ti coordination polyhedra form layers parallel_to the (100) which are connected by zig-zag chains of the Th coordination polyhedra which run in the [001] direction. The relations to another ThTi20 6 polymorph structure1 (isomorphous with brannerite) have been examined