Characteristics of La_0.8Sr_0.2Ga _(0.8x)Mg_0.2O_3-δ (x = 0.85, 0.9, 0.95, 1) electrolytes formed from powders prepared by spray pyrolysis

La_0.8Sr_0.2Ga_(0.8x)Mg_0.2O _3-δ (LSGM) (x = 0.85, 0.9, 0.95, 1) precursor powders were prepared by spray pyrolysis from spray solutions with various Ga contents. The pellets fired at 1400 °C had dense structures without pores, irrespective of the Ga content of the powders. The grain sizes of the pellets formed from powders with low Ga contents were larger than those of the pellets formed from powders with stoichiometric Ga contents. At firing temperatures of 1300 °C and 1400 °C, phase-pure LSGM pellets were obtained from powders with a stoichiometric amount of 85 at.% Ga (x = 0.85), as was evident from the results of crystal structure analysis. An orthorhombic-rhombohedral phase transition occurred in the pellets formed from powders with stoichiometric amounts of 95 at.% (x = 0.95), and 85 at.% (x = 0.85) Ga at a firing temperature of 1400 °C. The conductivities of LSGM with orthorhombic and rhombohedral structures sintered at 1400 °C were 0.007 S/cm and 0.022 S/cm, respectively, at a low measurement temperature of 600 °C.