Characterization of (La0.9Sr0.1)1+x(Ga0.8Mg0.2)O3-δ electrolytes with nonstoichiometric compositions

(La0.9Sr0.1)(1+X)(Ga0.8Mg0.2)O3-delta electrolytes with nonstoichiometric compositions were prepared by a traditional solid state reaction method. With increasing A-site concentration (X = 0.02 and 0.05), the total conductivity decreased due to the formation of the LaSrGaO4-related phase along the grain boundaries. On the other hand, with decreasing A-site concentration (X = -0.02 and -0.05), the conductivity increased at low temperatures because of the improvement of the grain boundary microstructure without any noticeable secondary phases. For the sample with X = -0.10, a large amount of LaSrGa3O7-related phase was formed only at the multiple grain junctions and not along the grain boundaries. This leads to only slight decrease in the electrical conductivity at the grain boundary.