Interface segregation of iron sintering aid in gadolinium-doped ceria

Sintering additives are commonly used in ceria-based oxide aiming at decreasing temperatures to prevent undesired reactions in several applications such as in solid oxide fuel cell functional layers. The role played by the sintering additive is studied in the case of Fe2O3 added to gadolinium-doped ceria (CGO). The distribution of iron on the CGO nanopowders was measured by a simple chemical method. The enhanced sintering of CGO is associated with the preferred segregation of iron species at the grain boundaries. Nevertheless, iron addition was found to change the distribution of gadolinium in the coprecipitated CGO powders. The saturation of the sintering aid at the grain boundary was induced by increasing the grain size of CGO. The resulting precipitation of iron-rich grains induced a small increase in the electrical conductivity of CGO. Increased sintering activity of Fe-doped CGO is related to the preferential segregation of iron species in CGO grain boundaries.