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 betw een 300 and 600 K. The temperature variation was strongly anisotropic, the maximum effect being observed in the [111] direction. At 10 MHz a relaxatio n peak was observed from which an activation energy of 0.7 +/- 0.07 eV coul d be estimated. A similar figure was obtained from dielectric constant meas urements, 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 ox ygen ions, one between Zr-related sites which can percolate the crystal and hence produce conduction, and another between Y-related sites which are lo calized.