Desorption of oxygen from calcia-stabilized zirconia

Samples of calcia-stabilized zirconia (CSZ), with calcia contents from 3.5 to 10 weight percent (w/o) and Fe2O3 contents from 0.024 to 1.64 w/o, have been saturated in oxygen at pressures from 100 Pa to 100 kPa and temperatures from 1228 to 1667 K. The oxygen was then pumped away to an ultimate vacuum of 10-4 Pa. The measured amounts of oxygen desorbed were independent of the calcia content but directly proportional to the iron oxide content. The observations were interpreted by means of a two-stage mechanism in which iron atoms have one change in oxidation state when oxygen is absorbed at low pressures and a further change upon absorption at high pressures. The low-pressure process has greater exothermicity