The Role of the Local Atomic Order and Boundary Effects on the Electrical Transport of Ceria

Heavily acceptor doped ceria is a material of great relevance for applications in solid oxide fuel cells and oxygen membranes. Depending on the operation temperature, dopant concentration and microstructure (e.g. nanocrystalline vs. microcrystalline), the ionic transport properties of ceria can be mostly hindered by (i) grain boundaries or (ii) local atomic disorder in the bulk. Here, we present a selection of examples (ranging from thin films to ceramics) of how and to which extent these effects can affect the electrical transport properties. Emphasis will be given to the case of heavily doped nanocrystalline and microcrystalline ceria doped with samarium, erbium and ytterbium (dopant concentrations between 10 and 30 at.%), whose outcomes (upon investigation by a.c. impedance spectroscopy as well as XRD and EXAFS) shed light on the role of different dopant size and concentration on the correlation between local atomic disorder in the bulk and ionic transport properties.