Synthesis and characterization of oxyanion (phosphate, sulfate) doped Ba\(_2\)Sc\(_2\)\(_-\)\(_y\)Ga\(_y\)O\(_5\)

In this paper we examine the effect of partial substitution of Ga for Sc in the oxyanion (phosphate, sulfate) containing perovskites, Ba2Sc\(_2\)\(_-\)\(_x\)P\(_x\)O\(_5\)\(_+\)\(_x\) and Ba\(_2\)S\(_c\)\(_2\)\(_-\)\(_x\)S\(_x\)O\(_5\)\(_+\)3\(_x\)\(_/\)\(_2\) 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 Ba\(_2\)S\(_c\)Ga\(_0\)\(_.\)\(_8\)P\(_0\)\(_.\)\(_2\)O\(_5\)\(_.\)\(_2\) and Ba\(_2\)S\(_c\)Ga\(_0\)\(_.\)\(_8\)S\(_0\)\(_.\)\(_2\)O\(_5\)\(_.\)\(_3\) for phosphate and sulfate doping respectively. While the Ga doping was shown to significantly improve the stability of the systems towards CO\(_2\) containing atmospheres, conductivity measurements showed a reduction in the conductivity with increasing Ga content.