Oxide ion conductivity measurements were made of pyrozirconates in which the rare-earth elements were partially replaced by Sr and the Zr was partially replaced by Al. Between 5 and 10at% of Sr, and very little Al, was found to enter the pyrochlore lattice. Alternating-current impedance measurements revealed an enhancement of the conductivity as a result of the incorporation of small amounts of Sr into both of the pyrochlores. In the case of the Gd2Zr2O7 system, this could be traced to an improvement in the grain interior conductivity by resolving the grain interior and grain boundary contributions to the total conductivity. This separation of bulk and grain-boundary conductivities was not possible in the case of the Nd2Zr2O7-based compositions. The observed variations in conductivity were explained in terms of the pyrochlore crystal chemistry.

K.V.G.Kutty, C.K.Mathews, T.N.Rao, U.V.Varadaraju: Solid State Ionics, 1995, 80[1-2], 99-110