A solid-state electrochemical technique was used to determine O diffusivities in the tetragonal phase at 850C. The samples were held in a calcia-stabilized ZrO2 cell, and the electromotive force was monitored as a function of time. The diffusivities were deduced by analyzing the time dependence of the electromotive force; during and after a current pulse. It was found that the chemical diffusivity of O increased slightly with positive deviations of the O content from stoichiometry. An average value of 5 x 10-5cm2/s was estimated for a temperature of 850C. The O component diffusivity was unaffected by deviations from stoichiometry, and had the same value as the average chemical diffusivity at 850C.

O.Porat, Z.Rosenstock, I.Shtreichman, I.Riess: Solid State Ionics, 1996, 86-88[2], 1385-9