It was recalled that the ionic conductivity of this material was still poorly understood. The aim here was to describe, by obtaining local fits to the Arrhenius law, the conductivity of monocrystals of ZrO2-12mol%Y2O3 at temperatures ranging from 200 to 1600C. This method yielded the pre-exponential factor and the activation enthalpy. The enthalpy values were fitted, using a least-squares procedure, to an empirical temperature-dependence function which had 4 adjustable parameters. In order to explain the results, and to interpret the physical meaning of the fitting parameters, a microscopic model was proposed which permitted a theoretical temperature dependence of the activation enthalpy, similar to the empirical function, to be deduced. By using this function, the association (0.57eV) and migration (0.73eV) enthalpies for O vacancies were determined, and the temperature variations of the free energy and entropy were analyzed, as well as the degree of dissociation of the vacancies which were involved in the conduction process. It was noted that, for the range of temperatures which was studied here, the extrinsic dissociated regime (where it was assumed that all of the O vacancies were free) was never reached. By taking account of the contribution of jumps up to the second-nearest anionic neighbors, a value of 1.31 x 1013Hz was obtained for the attempt frequency of O vacancies.

Ionic Conductivity of ZrO2–12mol%Y2O3 Single Crystals. J.D.Solier, I.Cachadiña, A.Dominguez-Rodriguez: Physical Review B, 1993, 48[6], 3704-12