ac conductivity of Na-Ag β” -alumina polycrystalline samples

The results of ac conductivity measurements carried out on ceramic samples of Li₂O and NiO-Li₂O-doped β7rdquo;-alumina with Na⁺, Ag⁺ and Na⁺ -Ag⁺ mobile ions are presented. The modifications of doping only slightly influenced either bulk or grain boundary conductivity in Na β” -alumina. The activation energies of conduction in Na β”-alumina equal to 0.28 eV at low temperatures decreased to 0.14–0.15 eV at temperatures above 200°C. The Arrhenius plots for Ag β” -alumina were found to be linear in whole 20–450°C temperature range with the activation energies of 0.19 eV (Li₂O) and 0.24 eV (NiO-Li₂O). The conductivity measurements done on partially exchanged samples revealed the presence of the mixed alkali effect.