An ultrasonic study of sodium ion diffusion in polycrystalline ß ß¨ alumina

Measurements are presented of the relative attenuation of longitudinal stress waves, of frequencies from 10 to 70 MHz, in polycrystalline samples of ß ß¨ alumina at temperatures from 80 to 300 K. The attenuation is found to exhibit a series of internal friction peaks, attributed to an interaction with Na+ ion diffusion. The activation energy for the diffusion of Na+ in the sample is estimated to be 0.142 eV. Shear wave attenuation is also found to rise at temperatures of ~300 K in samples contaminated by water absorption. © 1981.