Bismuth(III) containing oxides display numerous interesting properties, such as ionic conductivity, ferroelectricity, nonlinear optical properties, catalytic activity and superconductivity. The driving force for these properties is found in their structural features, often associated with the stereochemical activity of the Bi(III) lone pair. Most Bi2O3related oxide ion conductors which can be prepared by chemical doping fall into two categories: fluorite-type materials which retain the cubic structure of d-Bi2O3 or fluorite-related layered rhombohedral materials. The objectives of the experiments are:To determine the local structures of Bi0.775Ln0.225O1.5 (Ln = La, Dy) using a combination of neutron and X-ray total scattering and elucidate the Bi/Ln cation ordering and its role in superstructure formation,To determine the oxygen sublattice arrangement in the material.
