Mixed-Alkali Effect in Glasses of Different Classes in the Framework of a Microinhomogeneous-Glass-Structure Model

Abstract

By example of the silicate glasses with the compositions (33.3 – x)Li₂O·xNa₂O·66.7SiO₂ and (33.3 – x)K₂O·xNa₂O·66.7SiO₂ with purely cationic conductivity and chalcogenide glasses (Ag–Cu)_0.33AsSe_1.5 and (Ag–Cu)_0.61AsSe_1.5 with mixed ionic–electronic conductivity, consideration has been given to the describing of the mixed-alkali effect in bimetallic glasses in the framework of a microinhomogeneous-glass-structure model using additive schemes involving concentration dependences of conductivity of monometallic glasses with the monovalent metal content equal to that in the mixed glass. A satisfactory agreement between experimental and calculated data is demonstrated. Herein, in the alkaline silicate glasses the non-linear variation of the conductivity parameters is connected with the migration of two alkaline cations and sequential replacement of the conductivity mainly involving an ion by that involving another ion. In the studied chalcogenide glasses, a similar varying of electrical parameters is connected with the replacement of the majority current carrier upon the equivalent substituting of copper for silver in the glass bulk: the mixed, predominantly ionic conductivity is replaced by purely electronic one.