Anelasticity of Glass: III, Effect of Heat‐Treatment on the Internal Friction of Tank Plate Glass

Heat‐treatment or annealing decreases the internal‐friction peak commonly attributed to sodium ion diffusion in tank plate glass, a typical soda‐lime‐silica glass. The peak is shifted to higher temperatures at constant frequency of vibration or to lower frequencies at constant temperature. The activation energy for the shift is greater in the annealed glass and agrees with the activation energy for the electrical conductivity and alkali durability of annealed glass. Heat‐treatment also decreases the internal friction caused by elastico‐viscous effects.