Near-equivalence of the role of structural unpinning number, basicity and reciprocal average electronegativity in determining the conductivity of glasses

Abstract

The chemical approach made to investigate the origin of fast ion conduction in Agl-based fast ion conducting (FIC) glasses has been extended to various ionically conducting systems containing Na⁺ ion. An index known as structural unpinning number (SUN), S, has been defined for this purpose based on the unscreened nuclear charge on the cation and the average electronegativity of all the anions. Variation of the log(conductivity), at a given temperature, as a function of structural unpinning number, optical basicity, λ, and the reciprocal average electronegativity of all the anions, l/χ_a, has been examined for a number of Na⁺-ion conducting glasses and a nearly identical variation has been noticed in all the cases. The equivalence of these chemical parameters as determinants of the conductivity behavior of glasses has thus been established and the origin of this equivalence has been discussed.