The Internal Friction of Glasses

Basic fundamentals of the elastic behaviour of a standard linear solid and the internal friction technique based on this model are briefly described. The internal friction (Q ^-1 ) caused by various thermally activated processes in vitreous solids are reviewed for several glass compositions in relation to ionic mobility and other relevant properties. Similar relaxation mechanisms characterize many vitreous solids. The relaxation of alkali ions is essentially independent of the glass network former and has an activation energy of 15 to 25 kcal mol ^-1 . Other processes like the interaction of oxygen ions and protons, alkali ions and protons, mixed-alkali ion interaction and the motion of single bonded oxygen ions have an activation energy of 30 to 40 kcal mol ^-1 . The activation energy for relaxation of the glass network is 100 to 120 kcal mol ^-1 .