ELECTRONIC CONDUCTIVITY OF POLYCRYSTALLINE NA BETA-ALUMINA AT HIGH-TEMPERATURES .2. DETERMINATION OF EXCESS ELECTRON CONDUCTIVITY BY PERMEATION TECHNIQUE

T.he excess electron conductivity of three commercial sodium-ion condu cting beta-alumina solid electrolytes was determined by the permeation technique between 923 and 1073 K. At 1073 K the conductivity referrin g to the vapour pressure of pure metallic sodium lies between 1.1 and 2.9 X 10(-4) S/CM with the Li2O stabilized material exhibiting the low est values. The activation energies amount to 1.0...1.1 eV. In equilib rium with pure sodium the materials under investigation are expected t o remain within the electrolytic domain up to at least 1450 K.