CATION DISTRIBUTION IN MAGNETOPLUMBITE TYPE SRTI6CO6O19

The crystal structure of SrTi6Co6O19 has been refined in space group P 6,lmrne to an R-value of 0.045 (R(W) = 0.038). The distribution of the cobalt and titanium ions has been determined by refining the site occ upancy factors and by bond lengths considerations. Co2+ occupies the t etrahedral sites and Ti4+ is enriched on the octahedral sites in the s pinel S-blocks and in the face-sharing octahedra in the R-blocks of th e magneto-plumbite type structure, while Co2+ and Ti4+ are distributed at random over the trigonal bipyramid of the R-blocks and the octahed ra between the R- and spinel S-blocks. The cation distribution is disc ussed in terms of the Madelung part of lattice energy.