Gd3+ doped Ce oxides are very promising candidates as electrolytes for solid oxide fuel cells operating at ∼ 500 °C. For their successful commercial implementation, a full understanding of the defect chemistry in the bulk and at grain boundaries is essential. in particular, the contribution of the grain boundaries to the total ionic conductivity through such effects as the segregation of impurities, dopants and vacancies is of crucial importance. Here the effect of the atomic structure on the local electronic properties, i.e. oxygen coordination and cation valence at grain boundaries of the fluorite structured Gd0.2Ce0.8O2-x ceramic electrolyte is investigated by a combination of Z-contrast imaging and electron energy loss spectroscopy (EELS) in the JEOL 201 OF STEM (operating at 200keV, and aligned for a probe size ∼ 0.2 nm).
Preliminary O K- and Ce M45-edges were acquired from points in the grains (A and B) and grain boundary shown in Figure 1.