EFFECT OF OXYGEN-CONTAINING SPECIES ON THE IMPEDANCE OF THE PT YSZ INTERFACE/

The modifications induced by oxygen on the impedance spectra of Pt/YSZ (platinum/yttria-stabilized zirconia) interfaces at 900 degrees C hav e been studied. Oxygen atmosphere and oxygen transfer utilizing both p ositive and negative direct currents influenced the concentration of o xygen-containing species (OCS) at the interface and that is shown to a ffect the shape of the impedance response. Two main types of OCS have been identified. The effect of chemical stripping of the OCS by utiliz ing a reducing CO-CO2 atmosphere was also investigated. A mechanism fo r oxygen transfer across the Pt/YSZ interface is suggested. It involve s two parallel paths: direct, fast interfacial transfer of the O2- and a slow path, wherein the OCS participate.