Modification of B-site doping of perovskite LaxSr1 − xFe1 − y−zCoyCrzO3 − δ oxide by Mg2+ ion
Abstract Co-doping B-site of perovskite oxide La x Sr 1 −  x Co y Fe 1 −  y O 3 −  δ (LSCFO) with Cr 6+ and Mg 2+ ions has been attempted in this research for revamping chemical stability and oxygen ionic conductivity of this mixed conducting oxide. It is known that partial substitution for B-site cations of LSCFO by Cr gives rise to a significant improvement on chemical and thermal stability of the perovskite oxide. On the basis of this doped structure, introduction of an immaterial dose of Mg 2+ ion into its B-site results in a microstructure consisting of smaller grains with higher density than its precursor. Furthermore, the resulting perovskite oxide La 0.19 Sr 0.8 Fe 0.69 Co 0.1 Cr 0.2  Mg 0.01 O 3 − δ (LSFCCMO) displays higher O 2− conductivity than the solely Cr-doped LSCFO besides the improved chemical stability against reduction in 5% CH 4 /He stream at 850 °C. A detailed examination of the oxidation states of B-site transition metal ions by XPS has also been conducted as a part of structural characterizations of LSFCCMO. The assessment of relative O 2− conductivity shows that the grain boundary area plays a more important role than the bulk phase in facilitating ion transport, but with comparable boundary areas the higher densification level is favorable.