Synthesis and characterization of Sr- and Mg-doped Lanthanum gallate electrolyte materials prepared via the Pechini method

The powders of Sr- and Mg-doped lanthanum gallate (La0.85Sr0.15Ga0.80Mg0.2O2.825; LSGM) were synthesized by the Pechini method. The XRD pattern indicates that the main phase (LaGaO3) exists in the uncalcined powders. The LSGM materials are composed of the main phase without secondary phases when calcined at 1400 deg. C. The LSGM materials contain fewer amounts of secondary phases than those prepared by the sol-gel method and solid-state reaction method at the same calcination temperature. TEM image of the powders indicate that the average grain size is about 80 nm. The conductivity increases with the testing temperature increasing. The curve of ln(σT) vs 1/T exists two straight lines intersecting at T* (T* is about 602 deg. C). It indicates that activation energy of oxygen-vacancy motion at lower temperatures is greater than that at higher temperatures