Synthesis and characterization of oxyanion (phosphate, sulphate) doped Ba2Sc2−yGayO5

In this paper we examine the effect of partial substitution of Ga for Sc in the oxyanion (phosphate, sulphate) containing perovskites, Ba2Sc2−xPxO5+x and Ba2Sc2−xSxO5+3x/2 with the samples analysed through a combination of X-ray diffraction, TGA, Raman spectroscopy and conductivity measurements. The results demonstrate that in both cases, Ga can be incorporated in place of Sc up to 40%. In order to accommodate the increasing Ga content, a reduction in the oxyanion content is required. Thus for the highest Ga content sample achieved, only 10% oxyanion incorporation was achieved giving endmember compositions of Ba2ScGa0.8P0.2O5.2 and Ba2ScGa0.8S0.2O5.3 for phosphate and sulphate doping respectively. While the Ga doping was shown to significantly improve the stability of the systems towards CO2 containing atmospheres, conductivity measurements showed a reduction in the conductivity with increasing Ga content.

Phosphate and sulphate doped Ba2Sc2−xGaxO5 perovskites have been successfully prepared, with the highest conductivities observed for samples with the lowest Ga content.Figure optionsDownload as PowerPoint slideHighlights
► The successful synthesis of phosphate and sulphate doped Ba2Sc2−xGaxO5 perovskites.
► The demonstration of significant oxide ion and proton conduction in these perovskites.
► The demonstration of improved CO2 stability with increasing Ga content.