Charge transfer at oxygen/zirconia interface at elevated temperatures: Part 2: Oxidation of zirconia

The objective of the present paper is to review the literature on the mechanism and kinetics of oxidation of yttria-stabilised zirconia (YSZ) and related models of the transfer of charge and mass at the oxygen/zirconia interface at elevated temperatures. There is general agreement that oxygen may be incorporated efficiently into the lattice of zirconia at the triphase boundary (TPB), which is formed by the gas phase, zirconia oxygen ion conductor and electronic conductor. Thus, a number of efforts have been made to understand the effect of the TPB structure on the oxidation mechanism. Although it is clear that the TPB is required for efficient charge transfer at high current, there is a growing number of reports to the effect that oxygen may be incorporated into zirconia in the absence of the TPB. As a result, attempts have been made to develop zirconia for use in electrodeless zirconia-based electrochemical devices.