Application of lithium-silicate based oxynitrideglass into pH-responsive glass for improvement of responsibility and stability

A pH glass electrode are made of lithium-rich special glass, and the durability is often inferior in comparison with general hard glass. The glass electrode is often used under strong alkalinity or acidic conditions, and wherein the electrode has an extremely short life. In recent years, oxynitrideglasses have been reported in which a part of oxygen in the glass structure was replaced with nitrogen, for superior durability in strong acid and a strong alkaline solution. In this study, Li2O-SiO2-Si3N4 glass was prepared, and the possibility of the application as the pH responsive glass was checked. As a result, the new glass electrodes showed good response time for pH standard as short as ten seconds. Furthermore, its sensitivity between pH 4 and pH 9 was more than 97 % against theoretical value. The glass showed approximately 1/2 of silicon and lithium elution in alkaline solution for the chemical durability, compared with traditional pH responsive glass.