Structural features and enhanced high-temperature oxygen ion transport in SrFe1−xTaxO3−δ

Structural features, oxygen non-stoichiometry and transport properties are studied in the oxide series SrFe1−xTaxO3−δ, where x=0.2, 0.3 and 0.4. X-ray diffraction and electron microscopy data evidence formation of the inhomogeneous materials at x=0.3 and 0.4, which include phase constituents with a cubic perovskite and a double perovskite structure types. The composition, the amount and the typical grain size of the phase inhomogeneities are shown to depend both on doping and oxygen content. The increased oxygen-ion conductivity is observed in oxygen depleted materials, which is explained by the increase in the amount of cubic perovskite-like phase and development of interfacial pathways favorable for enhanced oxygen ion transport.

Graphical abstractThe structural studies, oxygen content and conductivity measurements suggest that oxygen depletion from the double perovskite phase constituent of SrFe1−xTaxO3−δ for x>0.2 is accompanied by formation of pathways for fast ion transport.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The double perovskite type regions are shown to exist in SrFe1−xTaxO3−δ. ► The oxygen depletion is accompanied with phase separation. ► The phase separation favors formation of pathways for enhanced oxygen ion transport.