Deposition and electrochemical characterization of Yttrium doped Barium cerate and zirconate heterostructures

Epitaxial heterostructures consisting of an yttrium doped barium cerate, BaCe_0.8Y_0.2O₃,(BCY) layer sandwiched between two yttrium doped barium zirconate, BaZr_0.8Y_0.2O₃,(BZY) thin layers have been deposited on insulating (001) MgO substrates by pulsed laser deposition. The first BZY layer was aimed at improving the lattice match with the MgO substrate, the second at protecting the BCY layer. Ionic conductivity has been studied in the 300 °C–600 °C temperature range as a function of the BCY thickness in dry air and wet 5% H₂ in Ar atmosphere. In both atmospheres, heterostructures showed a conductivity slightly larger than that of BCY pellets sintered under optimized conditions. Such a result has been attributed to the absence of blocking grain boundaries in the epitaxial heterostructures due to their good crystallographic quality. The BCY sandwich heterostructures showed an improved chemical stability relative to standard BCY pellets. - Highlights: • Heterostructures based on BaCe_0.8Y_0.2O₃ and BaZr_0.8Y_0.2O₃ were realized by PLD • Ionic conductivity has been studied in the 300 °C–600 °C range. • The conductivity was greater than that of optimized BaCe_0.8Y_0.2O₃ pellets • The result was ascribed to the high film quality and to the lack of blocking grains • The chemical stability was improved relative to standard BaCe_0.8Y_0.2O₃ pellets