The effect of cobalt oxide addition on the conductivity of Ce0.9Gd0.1O1.95

The conductivity of cobalt oxide doped Ce0.9Gd0.1O1.95 (CGO10) of various doping concentrations, sintering temperatures, dwell times, and cooling rates was investigated by 4-point DC conductivity measurements. In cobalt oxide doped CGO10, an enhanced total conductivity occuring with a low activation energy of 0.54 eV was detected below 250 degrees C in quenched samples. If the same samples were cooled down slowly, only the ionic conductivity of undoped CGO with an activation energy of 0.8 eV was found. The increased conductivity is attributed to a percolating network of an electronically conducting grain boundary phase rich in CoO, which can be retained by quenching from temperatures between 900 and 1000 degrees C.