Internal friction and dielectric losses of mixed alkali-alkaline earth metaphosphate glasses

Several series of glasses with the general formula xR2O · (1 - x)R' O · P2O5 were prepared and the dielectric loss and internal friction data were taken. The dielectric losses of alkali metaphosphate glasses are greatly reduced by the substitution of alkaline-earth oxide for alkali oxide. Some of the investigated series show a weak minimum in the dielectric loss. The internal friction measurements reveal a high temperature peak, in addition to the single alkali peak and the intermediate temperature peak commonly observed in phosphate glasses. The origin of this high temperature peak is discussed.