Pyrochlores with Pr as the A-site cation, and Zr, Sn, Ce and Mn cations on the B-sites, were prepared in air and their conductivities were investigated as a function of O partial pressure and temperature. Pure Pr2Zr2O7, as well as samples which were modified by B-site additions of 5%Mn or 20%Ce, exhibited conductivities which were lower than 0.002S/cm at 1000C in H2-H2O atmospheres. Electronic p-type conductivity was found for these same samples in O-N mixtures. Pr2Sn2O7 which was modified with 5%In on the B-sites exhibited a conductivity in air of 0.0065S/cm at 1000C.

Electrical Conductivities and Chemical Stabilities of Mixed Conducting Pyrochlores for SOFC Applications. P.Holtappels, F.W.Poulsen, M.Mogensen: Solid State Ionics, 2000, 135[1-4], 675-9