Constriction effect in the nearly constant loss of alkali metaphosphate glasses

We report measurements of the dielectric loss in a series of monovalent metaphosphate glasses at cryogenic temperatures. An analysis of the scaling properties of the dielectric response reveals a nonionic contribution to the loss present only in glasses for which the conduction cation is constricted by the oxide network. As a result, our effort to examine recent conflicting reports for the cation mass dependence of the nearly constant loss in ion-conducting, disordered materials has been obfuscated. Instead, it is shown how this nonionic contribution may explain additional conflicting observations for the nearly constant loss reported over the last 10 years.