Balaguer, M.; Sohn, Y.J.; Kobertz, D.; Kasatikov, S.; Fantin, A.; Müller, M.; Menzler, N.H.; Guillon, O.; Ivanova, M.E.: Characterization of Y and Mn co-substituted BaZrO3 ceramics: Material properties as a function of the substituent concentration. Solid State Ionics 382 (2022), p. 115959/1-14
10.1016/j.ssi.2022.115959
Open Access Version
Abstract:
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 BaZrO3, e.g. BaZr0.85Y0.15Mn0.05O3-δ, has previously attracted attention as a membrane material for H2 separation from gas mixtures due to its mixed proton-electron conductivity leading to appreciable levels of H2-flux at elevated temperatures and its good thermo-chemical stability under reducing environments. In the present work, we developed ceramic materials within the BaZr0.8Y0.2-xMnxO3-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 L2,3-edges indicated that the Mn atoms oxidation state in the surface and in the bulk range from Mn2+ to Mn4+ 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.