Electronically blocking grain boundaries in donor doped cerium dioxide

Thin films of 2 mol% Nb-doped cerium oxide are prepared via pulsed laser deposition and investigated using impedance spectroscopy. The electronic conductivity of various films having different microstructures is found to decrease with increasing grain boundary density. The defect chemistry is treated in terms of anti-Frenkel disorder, and possible origins of the blocking effect of the grain boundaries are discussed.

► Epitaxial and nanocrystalline donor-doped ceria films are investigated.
► The conductivity is lower in the nanocrystalline films than in the epitaxial films.
► The grain boundaries block the electronic conductivity.
► Both mobility as well as space charge effects can explain the lower GB conductivity.