Microstructure-conductivity relationship in Gd- and Sm-doped ceria-based electrolytes prepared by the acrylamide sol-gel-related method

We have prepared pure electrolytes of Ce0.8Gd0.2O1.9 (CGO) and Ce0.8Sm0.2O1.9 (CSO), useful for SOFCs, by a sol-gel-related technique like the acrylamide method. This method consists of preparing a solution from the single oxides followed by gelation. Then, the combustion or decomposition of the organic molecules is initiated, producing nanometric calcined powders of the above-mentioned compounds. Thermal treatments were optimized in order to obtain good electrochemical properties of the electrolytes. We have observed that the synthesis temperature to obtain the pure phase is lower for the sol-gel samples than for the pellets prepared by solid-state reaction, and the final density is higher. The microstructure and composition of the powders were characterized by TEM, SEM, and EDX analysis. The electrical properties of the electrolytes were measured by impedance spectroscopy at different temperatures and oxygen partial pressures.