Mixed Alkaline Effect in Antimony-Based Glasses

Abstract

© 2019, Pleiades Publishing, Ltd. Abstract: The mixed alkaline effect (MAE) is a well-known anomaly in glasses. It results in a non-linear response of various physical properties on mixing of alkali ions in the glass. In this paper, the MAE is studied in antimony oxides based glasses 60Sb2O3–20MoO3–(20 – x)Li2O–xNa2O and 60Sb2O3–20MoO3–(20 – x)Li2O–xK2O (in mol %). The influence of Na/Li and K/Li ratios on ionic AC and DC conductivities, and Tg is presented. Dependences of Tg on x, in both types of glasses, have typical minima at x ≅ 10, it means that the minima take place at approximately equal concentrations of both mixed alkali ions. The minimum for K2O containing glasses is deeper, probably due to a larger difference between ionic radii of K+ and Li+ ions. In glasses with one type of alkali ion, Tg decreases in the sequence: K → Li → Na. Temperature dependences of the DC conductivity obey Arrhenius-like relation. The conductivity steeply decreases with increasing Na or K content due to the larger ionic radius of both ions comparing to that of Li ions. At the same time, the conduction activation energy goes through a flat maximum at x = 15 (1.21 eV) for Na2O modifier and at x = 5 (1.16 eV), for K2O modifier. In antimony oxide based glasses, Li+, Na+, and K+ ions are modifiers and dominant charge-carriers. Due to larger ionic radii of Na+, and K+, the decrease of the conductivity after their addition is reasonable.