Influence of Annealing on the Electrical Conductivity of Polycrystalline ZrO 2 +8 Wt% Y 2 O 3

The electrical conductivity of partially stabilized zirconia was investigated as a function of frequency (2 Hz to 100 kHz) and temperature (400° to 1000°C) by measuring ac admittance on a 2‐probe cell using Lissajous figures. The dependence of the conductivity on annealing time was investigated with in situ conductivity measurements for prolonged annealing at 800°, 900°, and 1000°C. The aging behavior of two commercial zirconias was studied. At higher temperatures (7<750°C) the decrease in total conductivity arises mainly from changes within the grains, whereas at lower temperatures the decrease arises principally from the grain boundaries. Differences in initial conductivity and aging rates between samples from the two sources were related to grain size and impurity effects.