Characterization of Y and Mn co-substituted BaZrO 3 ceramics: Material properties as a function of the substituent concentration

Innovations in materials science are the key element for solving technological challenges. Various energy and environmental applications require designing materials with tailored compositions, microstructures and specific target-oriented performance. Y and Mn co-substituted BaZrO 3, e.g. BaZr 0.85 Y 0.15 Mn 0.05 O 3-δ, has previously attracted attention as a membrane material for H 2 separation from gas mixtures due to its mixed proton-electron conductivity leading to appreciable levels of H 2 -flux at elevated temperatures and its good thermo-chemical stability under reducing environments. In the present work, we developed ceramic materials within the BaZr 0.8 Y 0.2-x Mn x O 3-δ series, where x = 0.02–0.15. The study of their functional properties in dependence of the Y-to-Mn ratio disclosed that thermal expansion and hydration decrease by increasing the Mn content as well as the total electrical conductivity. In addition to that, XPS analysis and near edge X-ray absorption fine structure spectra (NEXAFS) in the vicinity of O K-edge and Mn L 2,3 -edges indicated that the Mn atoms oxidation state in the surface and in the bulk range from Mn 2+ to Mn 4+ depending on the ambient conditions that can be encountered in MPEC electrodes, which it is suggested to be related with a hydration mechanism mediated by Mn oxidation and subsequent proton attachment to oxygen neighbors, similar to LSM.