It was recalled that doped perovskites were of interest as electrolytes for solid-oxide fuel cells which operated at 600 to 1000C. Within this temperature range, they underwent a transition from protonic to oxide-ion conduction. The conductivity of BaCe0.9Gd0.1O2.95, which had previously been reported only for temperatures of up to 800C, was here measured up to 1200C by using the alternating current Van der Pauw technique. The data, which were obtained under various atmospheres and were plotted against the logarithm of the O partial pressure, exhibited ionic, p-type and n-type components. These could be resolved by curve-fitting with standard conductivity equations. The activation energy for ionic conduction was 0.52eV. This was used to calculate the ionic transport number under high and low O partial pressures, and to map out the ionic domain.

N.Bonanos: Journal of the Physics and Chemistry of Solids, 1993, 54[7], 867-70