Oxygen-ionic conductivity of perovskite-type La1−xSrxGa1−yMgyM0.20O3−δ (M=Fe, Co, Ni)

The oxygen-ionic conductivity of perovskite-type La1−xSrxGa0.80−yMgyM0.20O3−δ (x=0–0.20,y=0.15–0.20,M=Fe, Co, Ni) and La0.50Pr0.50Ga0.65Mg0.15Ni0.20O3−δ in air, determined by the measurements of total conductivity, faradaic efficiency and oxygen permeability at 973–1223 K, increases with increasing concentration of the acceptor-type dopants, within the solid solution formation limits. The level of ionic conduction in these phases is, however, lower than that in parent compounds, La1−xSrxGa1−yMgyO3−δ, probably due to partial oxygen-vacancy ordering and a higher average cation–anion bond energy in transition metal-containing gallates. The activation energy for ionic transport in La1−xSrxGa0.80−yMgyM0.20O3−δ varies in the range of 126–171 kJ mol−1. For compositions containing different transition metal cations, the ionic transport increases in the sequence M=Co