A Consistent Picture of Charge Distribution in Reduced Ceria Phases

We consider the implications of the bond valence model (BVM) description of charge distribution in reduced ceria phases (CeO$_{2-x}$)\cite{Shoko2009,Shoko2009b} to the models used to describe electronic and ionic conductivity in these phases. We conclude that the BVM is consistent with both the small polaron model (SPM) and the atomistic models which describe the electronic and ionic conductivities respectively. For intermediate phases, i.e., $x \sim 0.3$, we suggest the possibility of low temperature metallic conductivity. This has not yet been experimentally observed. We contrast the BVM results and the conventional description of charge distribution in reduced ceria phases.