ABSTRACT
Ceria is a ceramic that is a fast ionic conductor with some electronic semiconductivity. Its electrical properties are controlled by alloying additions (e.g. of gadolinia to form Ce1-xGdxO2-x/2-δ) and by sintering in reducing atmospheres. There is evidence that the ionic current is partially blocked by grain boundaries. REBIC microscopy of two samples of Ce1-xGdxO2-x/2-δ, with x = 0.1 and 0.2, subjected to strongly reducing anneals was difficult but possible. It was seen that some of the grain boundaries showed bright and others dark contrast while many were electrically inactive. The interpretation of these results is discussed.
