Bi<sup>3+</sup>/M<sup>2+</sup> Oxyphosphate: A Continuous Series of Polycationic Species from the 1D Single Chain to the 2D Planes. Part 2: Crystal Structure of Three Original Structural Types Showing a Combination of New Ribbonlike Polycations
2006-08-21T00:00:00Z (GMT) by
With the assistance of structural models deduced from the high-resolution electron microscope (HREM) investigation presented in Part 1 of this work, three new structural types were pointed out in Bi<sub>2</sub>O<sub>3</sub>−MO−P<sub>2</sub>O<sub>5</sub> ternary systems. Their crystal structures are built on the arrangement of 2D polycationic ribbons formed of edge-sharing O(Bi,M)<sub>4</sub> tetrahedra and isolated by PO<sub>4</sub> groups. Prior to this study, materials with ribbons up to <i>n </i>= 3 tetrahedra wide have been discovered. The original structures presented here display longer <i>n </i>= 4−6 cases, which suggests a possible continuous series of polycationic entities that range from the single chain (one tetrahedron wide) to the infinite [Bi<sub>2</sub>O<sub>2</sub>]<sup>2+</sup> Aurivillius layer. The ribbons with <i>n</i> > 3 show strong structural modifications that are able to bring a good ribbon−phosphate cohesion. In addition to these fascinating structural results, this work fully confirms the validity of the decoding established from HREM images of a single crystallite in inhomogeneous mixtures.