Characterization of adsorbed water layers on Y2O3-doped ZrO2

Chemisorption and physisorption of water from a humid atmosphere, on the ox ide Y2O3-doped ZrO2 (YSZ), were investigated by conductivity measurements a nd thermogravimetry (TG), in the temperature range 35-700 degreesC. Ionic c onduction is indicated to take place in a thin layer of water adsorbed on t he oxide. That ionic conduction is most probably proton conduction. At T < 600 degreesC, it can exceed the oxygen ion conduction within the YSZ bulk w hen the oxide is made of fine powder. The electrical conductivity measureme nts of YSZ fine powder in humid atmosphere are analyzed in terms of water c overage, defect formation and proton mobility in the water layers. Further analysis of the water coverage is done using TG measurements. The enthalpie s of defect formation and migration are determined. Results of preliminary conduction measurements of Al2O3 fine powder in a humid atmosphere reveal c onsiderable similarities to those of YSZ. (C) 2001 Elsevier Science B.V. Al l rights reserved.