Charge transfer at oxygen/zirconia interface at elevated temperatures Part 6: Work function measurements

The present paper considers the application of the high temperature Kelvin probe for measurements of changes in work function (WF) of oxide materials during surface reactions at elevated temperatures and in controlled gas phase environments. The method is based on the determination of work function changes from measurements of the contact potential difference (CPD) between the Pt reference electrode and the studied specimen of a metal oxide. Experimental data on work function changes are reported for yttria-stabilised cubic zirconia (10 mol-%Y₂O₃) during oxidation and reduction experiments at 1173 K. It was found that changes in CPD exhibit good stability with time (2 mV drift over 15 h). The reproducibility of CPD changes during successive oxidation and reduction experiments remains within 0.5 mV. Good agreement was revealed between the obtained experimental data and the theoretical model describing the effect of oxygen partial pressure on the WF of both zirconia and the Pt electrode.