Samples of commercial glass were ion-exchanged in KNO3/NaNO3 melts below, and slightly above, the glass transition temperature. The ion dynamics and transport were characterized by means of alternating-current conductivity spectroscopy. The results clearly demonstrated that mixed-alkali effects occurred in ion-exchanged glasses. These effects depended strongly upon the thermal history. In glasses which were exchanged below Tg, no conductivity minimum was observed as a function of the degree of exchange. When the exchange was performed slightly above Tg, a conductivity minimum was detected. The spectral shape of the conductivity, and the dependence of the direct-current conductivity upon the degree of exchange, indicated appreciable differences in the ion dynamics of glasses exchanged slightly above Tg, and melt-grown glasses having the same composition.

AC Conductivity and Ion Transport in K+-for-Na+ Ion-Exchanged Glasses - Exchange Experiments Below and Above the Glass Transition Temperature. M.Dubiel, B.Roling, M.Füting: Journal of Non-Crystalline Solids, 2003, 331[1-3], 11-9