Effect of Gd (Sm) doping on properties of ceria electrolyte for solid oxide fuel cells

Abstract Two systematic electrolytes of Ce 1− x Gd x O 2− x (GDC) and Ce 1− x Sm x O 2− x (SDC) ( x =0–0.25) were synthesized using an oxalate coprecipitation process. Dependence of a , unit cell parameter versus dopant concentration, x , of Gd 3+ and Sm 3+ ions show that these solid solutions obey Vegard’s rule as a =5.4121+0.0525 x for GDC and a =5.4117+0.1237 x for SDC, respectively. Electrical conductivity reached maximum at x =0.15 in the temperature range of 400–850 °C for both kinds of doped-ceria electrolyte membranes. A single cell was made for the measurement of open circuit voltage. The results show that the open circuit voltages are greatly influenced by ionic transference number of the electrolyte, gaseous fuel composition and cathode membrane material.