Abstract
Ceria (CeO2) based solid solutions are promising materials for use as solid oxide fuel cells electrolytes. Despite good electrical properties, one of the major drawbacks of these materials are the high sintering temperatures (typically above 1400 °C) required for full densification. In order to improve the ceria sinterability, transition metal oxides with low melting point have been used as sintering aid. In this context, the aim of this study was to evaluate the effect of gadolinia (Gd2O3) content on densification and electrical properties of ceria solid solutions with CuO as a sintering aid. Powders with nominal compositions Ce0.99-xGdxCu0.01O2-δ (x= 0, 0.2 and 0.3) were synthesized by the polymeric precursor method, calcined at 500 °C and characterized by X-ray diffraction (XRD). The relative density was evaluated in samples sintered between 950 and 1050 °C. The electrical properties were evaluated by impedance spectroscopy. The XRD results indicated the attainment of solid solutions with cubic fluorite type structure. The use of nanoparticle materials associated with a sintering aid allowed to obtain ceramics with relative densities higher than 92% after sintering at temperatures as low as 1000 °C. The total electrical conductivity was enhanced in samples with 20 mol% Gd2O3.
Keywords:
gadolinia doped ceria; polymeric precursor; sintering aid; electrical conductivity
