Clean renewable alternative energy source is a great issue of work nowadays. In a near future fuel cells will be the most promising answer of this issue. 8 mol% Yttria stabilized zirconia (8YSZ) is the most used material as electrolyte because of its ionic conduction and chemical stability under reducing and oxidant atmosphere, which allows that this device shows good efficiency at operating temperatures around 1000 ºC. Rare earth doped ceria has received special attention due to its high electrical conductivity that permits SOFC's to operate into a range of 500 to 800ºC. In this work Y doped ceria and Gd doped ceria electrical conduction are discussed as function of its microstructures obtained in different sintering conditions. 8YSZ results are also presented as reference. The grain electrical conductivity of rare earth doped ceria is bigger than 8YSZ. However, the grain boundary conductivity is mostly affected by the sintering conditions, specially sintering temperature and soaking time. It can be more than 1 order of magnitude smaller than grain conductivity. The grain boundary sensibility is related to the second phase formation along the grain boundary during sintering. The formation of this phase depends on the kind of dopants and it is clearly favored by the presence of Y2O3.
doped ceria; yttria doped zirconia; electrical conductivity; microstructure
