Diffusion and segregation along grain boundary at the electrolyte–anode interface in IT-SOFC

The atomic level chemical and microstructural features of grain boundaries in gadolinium-doped ceria (GDC) electrolyte thin film supported by Ni–GDC cermet anode were characterized by high resolution transmission electron microscope (HR-TEM) and scanning TEM (STEM). It was found that metallic Ni can diffuse from the anode into the thin film electrolyte along grain boundaries. In addition, Ce and Gd can also diffuse and segregate at grain boundaries between Ni grains in the anode substrate. HR-TEM observations revealed that Ni diffusion and segregation at grain boundaries between GDC grains enhanced the inhomogeneity and led to microstructural changes at grain boundary regions, i.e. the formation of superstructure. The observations also indicated that enhanced inhomogeneity at grain boundaries might play a significant role in the conductivity of GDC electrolyte film in solid oxide fuel cells.

► Elements spatial distributions and microstructures were characterized at the electrolyte–anode interface in IT-SOFC. ► Ni, Ce and Gd will segregate and diffuse along grain boundaries and lead to microstructure evolution, i.e. superstructure formation at grain boundaries.