Electrical conductivities of Sm-, Tb-, Pr- and Zr-doped ceria membranes were measured at 600 to 900C and PO2 = 10-22 to 0.21atm. Doping Sm and Pr in CeO2 respectively enhances the ionic conductivity and electron-hole conductivity of ceria. Sm-Pr doped ceria exhibited both n-type (at lower PO2) and p-type (at high PO2) electronic and ionic conductivity in the temperature range studied. Adding Tb in the Sm doped ceria caused a reduction in ionic conductivity. Zr-Pr doped ceria was an n-type electronic conductor at low PO2 and p-type electronic conductor at high PO2. The ionic conductivity of Zr-Pr doped ceria was lower than Sm doped ceria but higher than pure ceria. Oxygen permeation flux through the Zr-Pr doped ceria membrane, dominated by the slow O ionic conduction, was similar to the ytttria-doped bismuth oxide membrane, and smaller, but close to that of perovskite-type lanthanum cobaltite membrane.

Electric Conductivity and Oxygen Permeability of Modified Cerium Oxides. X.Qi, Y.S.Lin, C.T.Holt, S.L.Swartz: Journal of Materials Science, 2003, 38[5], 1073-9