Title: Electrical conductivity in Pb(II)- and Na(I)-Pb(II)-β″-alumina
Abstract:Pb(II)-β″-alumina, Pb0.83Mg0.67Al10.33O17, is a divalent isomorph of the well-known fast ion conductor, Na(I)-β″-alumina, and is distinguished by having the highest ionic conductivity of the known div...Pb(II)-β″-alumina, Pb0.83Mg0.67Al10.33O17, is a divalent isomorph of the well-known fast ion conductor, Na(I)-β″-alumina, and is distinguished by having the highest ionic conductivity of the known divalent β″-aluminas. The electrical properties of this compound are extremely sensitive to the presence of water. Pb(II)-β″-alumina reacts readily with water vapor to form a hydrated compound, Pb0.83Mg0.67Al10.33O17 - (H2O)x, in which x varies from 0 to 0.83. Hydration greatly decreases the ionic conductivity of Pb(II)-β″-alumina, and dehydration of the electrolyte in vacuum results in the chemical reduction of Pb(II) cations in the conduction layers and an insulator to semiconductor transition. The composition dependence of the ionic conductivity of anhydrous Na(I)-Pb(II)-β″-alumina has also been studied. Enhanced charge carrier correlation produces a minimum in the ionic conductivity at the composition at which 80% of the Na(I) ions are replaced by Pb(II). This paper describes the results of a study of ionic and electronic conductivity in Pb(II)- and Na(I)-Pb(II)-β″-alumina and the influence of hydration on the properties of the material.Read More