Ultrasonic attenuation due to localized relaxation in cubic yttria-stabilized zirconia

Longitudinal ultrasonic attenuation in yttria-stabilized zirconia [ZrO2(Y)] was measured at frequencies of 10 MHz and 120 MHz and at temperatures between 300 and 600 K. The temperature variation was strongly anisotropic, the maximum effect being observed in the [111] direction. At 10 MHz a relaxation peak was observed from which an activation energy of 0.7 +/- 0.07 eV could be estimated. A similar figure was obtained from dielectric constant measurements, but the ionic conductivity yielded a higher value of 0.92 +/- 0.1 eV. Our conclusion is that there are two separate hopping processes for oxygen ions, one between Zr-related sites which can percolate the crystal and hence produce conduction, and another between Y-related sites which are localized.