Defect and transport properties of nanocrystalline CeO2−x

It is shown that unique defect thermodynamics and transport properties result for oxides of a few nanometers crystallite size. Fully-dense CeO2−x polycrystals of ∼10 nm grain size were synthesized, and their electrical properties compared with those of samples coarsened from the same material. The nanocrystals showed reduced grain boundary resistance, 104 higher electronic conductivity, and less than one-half the heat of reduction of its coarse-grained counterpart. These properties are attributed to a dominant role of interfacial defect formation.