Fabrication of dense and defect-free diffusion barrier layer via constrained sintering for solid oxide fuel cells

To enable the development of next-generation solid oxide fuel cells (SOFCs), the fabrication of dense and defect-free diffusion barrier layers via constrained sintering has been a significant challenge. Here, we present a double layer technique that enables complete densification of a defect-free gadolinia-doped ceria diffusion barrier layer. In this approach, top and bottom layers were individually designed to perform unique functions based on systematic analysis of constrained sintering. The top layer, which contains 1 wt% CuO as a sintering aid, provides sufficient sintering driving force via liquid-phase sintering to allow complete densification of the film, while the bottom layer without a sintering aid prevents detrimental chemical reactions and regulates the global sintering rate to eliminate macro-defects. Such fabrication of dense diffusion barrier layers via a standard ceramic processing route would allow the use of novel cathode materials in practical SOFC manufacturing. Furthermore, the strategy presented in this study could be exploited in various multi-layer ceramic applications involving constrained sintering.