STRUCTURE REFINEMENTS OF THE LAYERED INTERGROWTH PHASES SB(III)SB(X)(V)A(1-X)TIO(6) (X-SIMILAR-OR-EQUAL-TO-0, A = TA, NB) USING SYNCHROTRONX-RAY-POWDER DIFFRACTION DATA

The structures of the layered intergrowth phases Sb(III)Sb(x)(V)A(1 - x)TiO(6) (x similar or equal to 0, A = Ta, Nb) have been refined by th e Rietveld method, using X-ray diffraction data obtained using a synch rotron source. The starting models for these structures were derived f rom those of Sb(3)(III)Sb(x)(V)A(3 - x)TiO(14) (x = 1.26, A = Ta and x = 0.89, A = Nb), previously solved by single crystal X-ray diffractio n. There were no significant differences between the derived models an d the final structures, validating the approach used to obtain the mod els and confirming that the n = 1 and n = 3 members of the family (Sbn SbxV)-Sb-III-A(n - x)TiO(4n + 2) are part of a structurally homologous series.