Bi3n+1Ti7Fe3n–3O9n+11 Homologous Series: Slicing Perovskite Structure with Planar Interfaces Containing Anatase-like Chains

The n = 3–6 members of a new perovskite-based homologous series Bi3n+1Ti7Fe3n–3O9n+11 are reported. The crystal structure of the n = 3 Bi10Ti7Fe6O38 member is refined using a combination of X-ray and neutron powder diffraction data (a = 11.8511(2) A, b = 3.85076(4) A, c = 33.0722(6) A, S.G. Immm), unveiling the partially ordered distribution of Ti4+ and Fe3+ cations and indicating the presence of static random displacements of the Bi and O atoms. All Bi3n+1Ti7Fe3n–3O9n+11 structures are composed of perovskite blocks separated by translational interfaces parallel to the (001)p perovskite planes. The thickness of the perovskite blocks increases with n, while the atomic arrangement at the interfaces remains the same. The interfaces comprise chains of double edge-sharing (Fe,Ti)O6 octahedra connected to the octahedra of the perovskite blocks by sharing edges and corners. This configuration shifts the adjacent perovskite blocks relative to each other over a vector 1/2[110]p and creates S-shaped tunnels along t...