Superlinear frequency dependence of AC conductivity and its scaling behavior in xAgI-(1 − x) AgPO3 glass superionic conductors

•Low temperature ac conductivity and its scaling properties are studied for xAgI-(1 − x) AgPO3 glass superionic conductors•Undoped glass shows superlinear ac conductivity at very low temperatures, whereas doped glasses show only sublinear Jonscher power law behavior at all temperatures studied•All glasses obey Summerfield scaling law in the Jonscher power law regime.•Scaling law is not obeyed in superlinear regime indicating different physical origin of superlinear behavior than that of Jonscher behaviour

Low temperature AC conductivity studies on melt quenched xAgI-(1 − x) AgPO3 glass electrolytes are presented. It is observed that doped glasses show Jonscher power law behavior at all temperatures, however, undoped AgPO3 glass also shows superlinear frequency-dependent conductivity at very low temperatures apart from the usual Jonscher power law behavior. This behavior in undoped AgPO3 glass is not yet reported in literature. The Summerfield scaling law is used to demonstrate that Jonscher power law behavior and superlinear power law behavior have different physical origins as scaling law is not followed in the superlinear regime. Moreover, scaling behavior of AC conductivity also indicates that conduction mechanisms are slightly different in doped and undoped glasses. However, scaling behavior provides only qualitative information about the conduction mechanisms. The conductivity spectra of doped and undoped glasses can be merged into a super-master conductivity curve except in the transition zone (where AC conductivity starts dominating over DC conductivity) where the conductivity master plots of doped and undoped glasses do not merge.