Ba2In2-xMExO5+δ oxide ion conductors: structure, conductivity, oxygen migration
Résumé
The brownmillerite Ba2In2O5 is a non-stoichiometric oxide ion conductor. At room temperature, it can be described at room temperature as an oxygen-ordered-vacancy defect perovskite in which one-sixth of the oxygen ions of the perovskite structure is replaced by an ordered array of vacancies, producing alternating octahedral and tetrahedral layers (Figure 1). For temperature higher than 925°C, the vacancies disorder and the symmetry becomes tetragonal and then cubic. With the aim to stabilise at lower temperature these two forms which are pure oxide ion conductors, partial substitution were performed on the indium site.