Application of the high-temperature Kelvin probe for in situ monitoring of the charge transfer at the oxygen/zirconia interface. Oxygen chemisorption isobar

Abstract

The present work describes application of the high-temperature Kelvin probe for in situ monitoring of the charge transfer at the gas/solid interface at elevated temperatures (up to 1200 K) using work function measurements. Performance of the probe is described for the oxygen/zirconia system at elevated temperatures. The work function data for yttria-stabilized (10 mol%) zirconia during oxidation in the temperature range 298–1173 K are reported. The determined work function changes during oxidation are considered in terms of the reactivity mechanisms between oxygen and zirconia, such as oxygen incorporation and oxygen chemisorption. The effect of temperature on the oxygen chemisorption isobar is considered in terms of surface coverage of zirconia with chemisorbed oxygen species, including singly ionized atomic species and singly ionized molecular species. The respective chemisorption isobars, determined at p(O 2)=21 kPa, exhibit maxima at ∼300 and 1000 K.