Perovskite-type sinters of non-doped BaxCeO3, where x was between 0.90 and 10, were investigated. The X-ray powder diffraction patterns of the sinters indicated that specimens with x-values of between 0.95 and 1.10 were single-phased orthorhombic perovskite-type BaCeO3, while those with x = 0.90 were mixtures of perovskite and CeO2 impurity. Conduction in specimens with x-values of between 0.95 and 1.05 was studied electrochemically at temperatures ranging from 600 to 1000C. The conduction was markedly affected by Ba2+:Ce4+ site non-stoichiometry. Specimens with excess Ba exhibited predominantly ionic conduction (H+ + O2-), with an ion transport number that was greater than 0.5 under a H atmosphere. They exhibited a poor oxide ionic conduction (with an oxide-ion transport number of less than 0.1) in oxidizing atmospheres. Proton conduction in these specimens, in a reducing atmosphere, was confirmed by electrochemical H permeation data. On the other hand, specimens with x-values of less than unity exhibited predominantly O-ionic conduction (with an O-ion transport number greater than 0.8) in an oxidizing atmosphere. Poor ionic conduction (with an ion transport number of less than 0.1) was observed in H ambients.

Ionic Conduction and Nonstoichiometry in Non-Doped (Ba,Ce)O3. G.Ma, H.Matsumoto, H.Iwahara: Solid State Ionics, 1999, 122[1-4], 237-47