Physicochemical compatibility of SrCeO3 with potential SOFC cathodes

The chemical and physical compatibility of SrCeO3 is investigated with respect to LaMO3 (M = Mn, Fe, Co) and La2-x.SrxNiO4 (x = 0, 0.8) via the reaction of fine-grained powder compacts and solid-state diffusion Couples. Compositions were chosen so as to give predictive insight into possible candidate materials for all-oxide electrochemical devices. Results show the primary reaction in these systems to be the dissolution of SrO from SrCeO3 into the LaMO3/La2-xSrxNiO4, and corresponding formation of La-doped CeO2. Reaction kinetics are observed to be relatively fast, with element profiles Suggesting the diffusion of Sr2+ in ceria to be surprisingly rapid. It is demonstrated that perovskite starting materials represent poor candidates for use with SrCeO3, reacting completely to form Ruddlesden-Popper/K2NiF4 type oxides. Reaction with LaNiO4 is less pronounced, and formation of secondary phases suppressed for the composition La1.2Sr0.8NiO4. It is thus concluded that Ruddlesden-Popper type oxides represent good candidate materials for use with a SrCeO3-based electrolytes when doped with appropriate levels of Sr. (C) 2007 Elsevier Inc. All rights reserved.