The effect of the Ga content was investigated (figure 5). It was found that the substitution of Ga at Al sites enhanced the O ion conductivity of Nd0.9Ca0.1AlO3, and the highest O ion conduction was found for an x-value of 0.5 in Nd0.9Ca0.1Al1-xGaxO3. The conductivity was essentially independent of O partial pressures of between 10-20 and 1atm. The O ion conductivity of Nd0.9Ca0.1Al0.5Ga0.5O3 at 1223K was of the order of 0.04S/cm. It was also estimated that the oxide ion transference number was almost equal to unity over a wide range of O partial pressures and temperature.

T.Ishihara, H.Matsuda, Y.Mizuhara, Y.Takita: Solid State Ionics, 1994, 70-71, 234-8