ABSTRACT
The ionic conductivity of tetragonal (t’ and t) and cubic ZrO2 doped with 15–45 mol% InO1.5 has been investigated by impedance spectroscopy and DC 4-probe measurements up to 1000°C Both t’~ and t-phase polycrystals with the same InO1.5 concentration were prepared via cooling from the cubic phase field and low-temperature sintering, respectively. The t-phase reveals higher intragrain ionic conductivity and a lower activation energy, compared to the t’-phase of the same solute concentration. On the other hand, the total conductivity of the fine polycrystalline t-phase is lower than that of the coarser-grained t’-phase because of its larger grain boundary resistivity. The total ionic conductivity of the polycystalline cubic phase near the eutectoid composition is comparable to the total conductivity of 8 mol% Y2O3-doped ZrO2.
Tetragonality and domain size of the t’-phase are strongly dependent on cooling conditions from high temperature.
