Oxyanion doping strategies to enhance the ionic conductivity in Ba2In2O5

In this paper we report the successful incorporation of phosphate and sulphate groups into the ionic conductor, Ba2In2O5, with the samples analysed through a combination of X-ray diffraction, NMR, TGA, Raman spectroscopy and conductivity measurements. The results show that such oxyanion incorporation leads to a conversion from an ordered brownmillerite-type structure to a disordered perovskite-type, and hence increases the conductivity at temperatures < 800○C. In wet atmospheres, there is evidence for a significant enhancement of the conductivity through a protonic contribution.