Improvement of ionic conductivity of gadolinium doped ceria electrolyte with nano CuO sintering aid

Gadanium doped cerium oxide ceramic (GDC) is widely used as solid electrolytes in solid oxide fuel cells because of its high oxygen ion conductivity. In this study, the effect of addition of nano CuO as a sintering aid on the properties of GDC electrolyte were investigated. For this purpose, 0.2, 0.5, and 1% mole of nano Cuo was added to GDC ceramics, which was synthesized by the solid-state method and the effect in microstructure and ionic conductivity of this solid electrolyte were investigated. The results of X-ray diffraction showed that the presence of the CuO phase as an impurity phase was detected by adding 1% mole nano CuO. Based on the results of density and ionic conductivity, 0.5% mole nano CuO was introduced as the optimal value. With the addition of 0.5% mole nano CuO, the density of GDC ceramic increased to 97% theoretical density and the ion conductivity improved by 89%. The SEM results showed that adding nano CuO had a great effect on the microstructure of the GDC ceramic and the uniform microstructure was obtained. An increase in ionic conductivity and a decrease in the activation energy of GDC electrolyte in the presence of nano CuO could be due to increased density, grain growth and reduced resistance of grain boundaries.