Influence of small amounts of gallium oxide addition on ionic conductivity of La0.9Sr0.1Ga0.8Mg0.2O3-δ solid electrolyte

The effects of small amounts of gallium oxide on intragrain and intergrain conductivity of La0.9Sr0.1Ga0.8Mg0.2O3.delta are investigated by impedance spectroscopy in the 280-420 degrees C range. Bulk specimens with 0.5, 1.0 and 1.5 mol% gallium oxide are prepared by solid state reaction at 1350 degrees C. All specimens achieved relative density values higher than 95%. The additive promotes grain growth indicating solid solution formation. A small fraction of the additive remains at grain boundaries and increases the fraction of the gallium-rich, LaSrGa3O7, impurity phase. The intragrain conductivity of gallium oxide containing specimens is higher than that of the parent solid electrolyte. Similar effect is found for the intergrain conductivity, which is maximum for 1 mol% gallium oxide addition.