Co-doping was used to enhance the ionic conductivity of ceria-based electrolytes. Sm3+ and Nd3+ were selected as co-dopants to promote low migration energy paths for O vacancy diffusion, thereby increasing the ionic conductivity. Moreover, the use of co-dopants also increased the pre-exponential factor in the Arrhenius relationship, thus further improving the ionic conductivity. The ionic conductivity of SmxNdxCe1−2xO2−δ solid solutions was measured using electrochemical impedance spectroscopy. It was observed that for Sm0.075Nd0.075Ce0.85O2−δ, the grain ionic conductivity was 0.014S/cm at 550C, which makes it one of the most promising ceria-based electrolytes for intermediate temperature solid oxide fuel cells.

Higher Ionic Conductive Ceria-Based Electrolytes for Solid Oxide Fuel Cells. S.Omar, E.D.Wachsman, J.C.Nino: Applied Physics Letters, 2007, 91[14], 144106