Characterization of Pt,O2|YSZ electrodes for lambda probes and their ageing in humid atmosphere

Abstract

Abstract Electrodes with different microstructures made of platinum and yttria stabilized zirconia (YSZ) were investigated. They were characterized by means of impedance measurements and electrode charging experiments in the temperature range of 450 ℃ to 800 ℃ and in oxygen partial pressures of 0.2 bar down to 10−5 bar. Samples were characterized before and after an ageing step at 690 ℃ in water vapour containing atmosphere. Microstructural data were determined by a 3D microstructure reconstruction from SEM image stacks. Results indicate that a large platinum surface or a high triple phase boundary (TPB) density both lead to a lower electrode impedance and stabilize the electrode against degradation in humid atmosphere.