Grain boundary conductivity enhancement in ceria-gadolinia solid solutions

The electrical conductivity of ceria-gadolinia (CGO) with small additions of calcium have been studied in an attempt to improve the grain boundary conductivity. The results show that a large increase in the grain boundary conductivity is obtained, which is attributed to a higher ionic conductivity calcium phase at the grain boundary. The best total conductivity was found for a 9mol% Gd-1mol% Ca sample. D.C. Conductivity results taken at selected pO(2) at 750 degrees C, showed the conductivity to be ionic at high pO(2)'s and electronic at pO(2)'s lower than 10(-15) atm.