Internal Friction of Aluminoborosilicate Glasses with Small Amounts of Alkalis

Abstract

glasses was measured by a free damping method, and the minimum alkali content for exhibiting the mixed alkali or mixed cation eect was determined. In the former glasses, two independent peaks at lower temperatures caused by the movement of K and Na ions were observed for glasses containing less than 4 mol÷ alkali content. In the lat ter system, similar peaks were recognized for glasses containing less than 7 mol÷ total cation contents. These results conrmed that no mixed alkali eect appears for glasses containing a small content of alkalis and that the eect of mixed cation eect is less pronounced than the mixed alkali eect.