Grain‐Boundary Effect in Ceria Doped with Trivalent Cations: I, Electrical Measurements

The “grain‐boundary effect,” which leads to a greatly reduced dc ionic conductivity due to the presence of a blocking layer in the vicinity of the grain boundaries, is studied in detail for ceria ceramics doped with various trivalent dopants (particularly Y 3+ , Gd 3+ , and La 3+ ). The effects of porosity, of sintering time, and of dopant size and dopant concentration are investigated. Finally, it is shown that the grain‐boundary effect virtually disappears when nearly silicon‐free starting materials are used.