Mixed conductivity, thermal expansion, and oxygen permeability of Ce(Pr,Zr)O2 − δ

Zr substitution leads to a decrease in total conductivity and an increase in average grain size. Oxygen permeability in these materials is controlled by both ambipolar bulk conductivity and oxygen surface exchange rates. Typical values of specific oxygen permeability are approximately 3 × 10− 8 mol/s cm at 1000 °C and compare well with other phases that are promising as oxide catalyst supports and precursors, such as La(Fe,Ni)O3 − δ perovskites. A decrease in both ionic and electronic conductivities is observed with decreasing p(O2) by measurements of oxygen concentration cell emf combined with impedance spectroscopy. Ion transference numbers show a positive temperature dependence, with typical values to = 0.8 at 950 °C under oxidizing conditions.