Internal Friction of NaPO₃ Glasses Containing Water

The internal friction of sodium metaphosphate glasses containing from 0.016 to 0.330 wt% water has been investigated. Weight loss and infrared absorption measurements were used to determine the water content. Of the two internal friction peaks observed between -100°C and ~250°C, the second peak occurring above room temperature has a pronounced dependence upon the water content; increasing water content causing the activation energy to decrease as the peak increased in size. A mechanism consisting of the cooperative motion of sodium ions and protons has been proposed for this peak. It is concluded that the second peak in the NaPO3 glasses and the similar peak in alkali silicate glasses is not associated with the movement of the non-bridging oxygen ions