Synthesis and Crystal Structure of a New Iodate (Pb0.6Ba0.4)(Pb0.4Ba0.6)[IO3]4 Analogous to Sr[IO3]2

Abstract

Crystals of a new triclinic iodate with the formula (Pb_0.6Ba_0.4)(Pb_0.4Ba_0.6)[IO₃]₄ (sp. gr. P\(\bar {1}\)) were prepared by hydrothermal synthesis. These crystals are isostructural with the previously characterized iodate Sr[IO₃]₂. Reliable structural data were obtained by applying corrections for absorption and twinning. The structure contains isolated umbrella-like [IO₃]^– groups typical of iodates, which are located at the same levels in layers parallel to the bc plane. The sites between these layers are isomorphously occupied by large Pb and Ba cations in a nearly 1 : 1 ratio, thereby allowing the retention of the structure type of Sr-containing compounds despite the incorporation of a larger Ba atom into the Pb site. This fact can be used in the synthesis of new iodates.