Mobility of Sodium Ions in Silica Glass of Different OH Content

Using 22Na as a radiotracer, mobilities of sodium ions in various types of SiO2 glasses were measured and found to depend on the OH content in the silica network. Increasing OH content in SiO2 considerably reduces the Na mobility. The effect of immobilization of Na is discussed in terms of an interaction between hydrogen and sodium ions, similar to the “mixed-alkali effect” in alkali silicate glasses. High OH-containing SiO2, structures display the lowest diffusivities of either sodium or hydrogen ions, thus indicating properties which are preferential in practice, such as decreasing ionic instabilities in metal-oxide-semiconductor devices.