Application of the High Temperature Fermi Probe in Studies of Charge Transfer at the Gas/Solid Interface. Example of the Oxygen/Zirconia System

This work describes the high temperature Kelvin probe as a unique surface sensitive tool for the following specific characterizations: Determination of semiconducting properties of the surface layer of materials at elevated temperatures and in the gas phase of controlled composition Determination of the chemical potential of electrons of the outermost surface layer and its in situ monitoring during processing of materials including sintering, annealing, equilibration, chemisorption, segregation and doping, and surface engineering procedures Determination of the transport kinetics of ions within the surface layer and related diffusion data In situ monitoring of chemical reactions taking place at the surface, such as catalytic reactions and chemisorption, and related charge transfer at the gas/solid interface. The present paper reports the experimental data for the oxygen/zirconia system illustrating the performance of the high temperature Kelvin probe during oxidation and reduction of zirconia at elevated temperatures at which performance of zirconia in electrochemical devices has been widely described. Specifically, this work considers the effect of surface processing, such as polishing and annealing, on isothermal oxidation of polycrystalline yttria-stabilized cubic zirconia (10Y-ZrO₂) at 1173 K. The oxidation is discussed in terms of oxygen chemisorption and oxygen incorporation into the zirconia lattice.