A geometric characterization and modelling of microstructure development for ceramics composites BaZr0,9Y0,1O3-d + BaCe0,9Y0,1O3-d ( BCY-BZY)

The growing global demand on energy and the environmental problems due to pollution emission has stimulated extensive research in sustainable sources of energy with highlight to electrochemical conversion of energy and the use... [ view full abstract ]

The growing global demand on energy and the environmental problems due to pollution emission has stimulated extensive research in sustainable sources of energy with highlight to electrochemical conversion of energy and the use of biofuel. Solid oxide fuel cells (SOFCs) work through electrochemical conversion of energy and show high efficiency and wide application range with fuel flexibility. The most common material used to this application is YSZ, however the high temperatures of operation is a challenge for this technology. Currently, proton conducting ceramics have attracted interest as alternative YSZ and in this way Barium-Cerates and Zirconates have drawn attention as a candidate to electrolyte. Several strategies have been adopted to improve the performance of these materials as solid electrolytes: co-doping, metallic, rare-earth elements, composites and advanced techniques on processing to provide a control of microstructures. BaZr0,9Y_0,1O₃ and BaCe_0,9Y_0,1O₃ based ceramics powders were prepared through solid state reactions aiming at to prepare composites, calcined and sintered through several schedules. The composite emerges as a solution to promote high conductivity interfaces and also obtain a material with high sinterability and stability, which are properties reported to BCY-BZY.  The fracture and polished surfaces were analyzed with Scanning-Electron-Microscopy and geometric parameters were obtained using ImageJ freeware. Values of grain size, polygons characterization, edges lengths and their distribution were compared in ceramics with densification higher than 90% of theoretical density and sintered in distinct schedules. The results have shown that microstructure geometric parameters and their distribution have strong dependence on heating rate, dwell time and sintering temperature even in similar values of density. Additionally, it has been observed that the increasing amount of BCY in the composite also improve its sinterability, compared to BZY sinterability, and this result can be related to the lower sintering temperatures observed to obtain dense ceramics based com Barium Cerate.