Crystal Structure Analysis on Long- and Short-Range of Doped Ba2In2O5

We are investigating transition metal doped brownmillerite-type mixed ionic-electronic conducting (MIEC) Ba2(In1–xMx)2O5 with M = Sc–Cu and 0 ≤ x ≤ 0.9 (depending on dopant solubility) as ceramic oxygen transport membrane (OTM) model system for plasma-assisted carbon dioxide utilisation. For pristine Ba2In2O5 it is well-known that the total conductivity increases by several orders of magnitude upon the phase transition from lower symmetry to cubic. Hence, it is of strong interest to understand how doping can be used to establish a (pseudo-)cubic structure already at lower temperature. Detailed synchrotron diffraction analysis of the doped Ba2In2O5 on global and local scale is highly needed in order to proof the absence of superstructure reflections and link the crystal structure changes to the observed oxygen permeation performance.