Electrical conductivity of doubly doped ceria

The results of structural and electrical measurements of ceria-based materials containing gadolinium and second dopant from a group of Y, Sm and Nd are presented. The samples with total amount of dopant equal 15 at.% were synthesized using a co-precipitation method. XRD measurements indicate that all obtained materials were single phase. A linear dependence between the lattice parameter and the average ionic radius was observed. The grain boundary (σgb) and bulk (σbulk) conductivities were measured on dense pellets by means of EIS. An improvement of the electrical conductivity in comparison with the best singly doped ceria: Ce0.85Gd0.15O1.925 was observed for Gd–Y and Gd–Sm doubly doped samples, but only for the bulk component of the conductivity. The grain boundary conductivity, as well as total conductivity in all doubly doped ceria was found to be lower than for Ce0.85Gd0.15O1.925. Also, the activation energy observed for Ce0.85Gd0.15O1.925 sample was the lowest among all tested materials.