Properties and microstructural analysis of La1−xSrxGa1−yMgyO3−δ solid electrolyte ceramic

La1−xSrxGa1−yMgyO3−δ (x=0.1–0.2, y=0.1–0.2) (LSGM) electrolytes, which have high ionic conductivities, were synthesized by a solid-state reaction at 1500 °C. In our study, La0.9Sr0.1Ga0.9Mg0.1O3−δ and La0.9Sr0.1Ga0.8Mg0.2O3−δ crystallized in an orthorhombic (Imma) structure, and La1−xSrxGa1−yMgyO3−δ (0.10.35, the conductivity was approximately 0.164–0.173 S/cm at 800 °C. The ionic conductivity mechanism changed at temperatures of approximately 500–650 °C. La0.9Sr0.1Ga0.9Mg0.1O3−δ and La0.9Sr0.1Ga0.8Mg0.2O3−δ samples possessed higher resistances at 300–400 °C as a result of existing stacking faults and defects. The thermal expansion coefficients (TECs) were approximately 9.1×10−6/°C to 11×10−6/°C at 200–500 °C.