Electrical characterization of multidoped ceria ceramics

Ceria ceramics was obtained from multi-doped nanosized ceria powders prepared by both modified glycine nitrate procedure (MGNP) and self-propagating reaction at room temperature (SPRT). Rare earth elements such as Nd, Sm, Gd, Dy, Y, Yb were used as dopants. The overall mole fraction of dopants was 0.2. One-hour long sintering of powder compacts was performed at 1500 °C in oxygen atmosphere. Phase composition, microstructure and ionic conductivity of sintered samples were analysed. Single-phase ceria was detected in all samples. In general, the increase in the number of dopants improved the ionic conductivity. The samples doped simultaneously with five dopants had the highest ionic conductivity, as evidenced by the impedance measurements. At 450 °C, the conductivity of sample obtained by MGNP was 3.94×10−3 Ω−1 cm−1 whereas the conductivity of sample obtained by SPRT was 2.61×10−3 Ω−1 cm−1. The conductivity activation energy for MGNP and SPRT samples was measured to be 0.348 and 0.385 eV, respectively. Finally, the conductivity decreased as the number of dopants increased to six.