Synthesis and characterization of composite electrolytes based on samaria-doped ceria and Na/Li carbonates

Samaria-doped ceria-based composites with a 2:1 addition of Li and Na carbonates (or simple Na carbonate as admixture) were prepared mixing nanosized powders of the ceramic phase with the remaining constituents. Samples fired at relatively low temperatures (below 700 °C) were characterized by X-ray diffraction, scanning electron microscopy combined with energy dispersive spectroscopy and impedance spectroscopy in air. These composites showed a complex but homogeneous distribution of both phases, with one ceramic skeleton of bonded nanosized grains surrounded by the carbonate-based phase. Impedance spectroscopy data was used to confirm the impressive electrical conductivity of these materials, but also to put into evidence the complex nature of the charge transport process, clearly deviating from classical electrolytes.