Characterization of inter-diffusion phase between gadolinium-doped ceria and yttria-stabilized zirconia during high-temperature sintering by in-situ and ex-situ transmission electron microscopy observations

Formation of an inter-diffusion phase of gadolinium-doped ceria (GDC) and yttria-stabilized zirconia (YSZ) during high-temperature sintering is a significant issue to deteriorate the electrochemical performance of solid oxide fuel cell electrodes. In the present study, microstructural change of GDC particles on a YSZ substrate and formation of a secondary phase during high-temperature sintering was observed by an in-situ transmission electron microscopy (TEM). A TEM sample was fixed on Nano-Chip (Wildfire, DENSsolutions), and the in-situ observation was carried out at 1300 °C. For comparison, an additional observation by TEM was also carried out using the sample prepared in ex-situ condition. Formation of inter-diffusion phase was observed in both experiments. However, grain growth and interfacial microstructure were different in each experiment. Based on the differences between the two tests, mechanisms of microstructural evolutions of GDC and interfacial structure are discussed.