Ionic conductivity, electric modulus and mechanical relaxations in silver iodide–silver molybdate glasses

• Dielectric properties of silver iodomolybdate glasses studied vs. frequency and temperature.
• Comparison between electrical response and peculiar mechanical response in modulus formalism.
• Primary relaxation associated with ionic hopping: scaling of electric and mechanical spectra.
• Signature of secondary processes more evident in mechanical spectra than in electric spectra.
• Excess loss more relevant in molybdate glasses than in other silver based ionic glasses.

Silver iodide–silver molybdate glasses, (AgI)x(Ag2MoO4)1 − x, with x = 0.75 and x = 0.67, exhibit high ionic conductivity, comparable to that of some ionic liquids at room temperature, and low values of the calorimetric glass transition temperature. The behaviour of the attenuation of acoustic waves as a function of temperature in silver iodomolybdate glasses below Tg is peculiar, arising from two different and almost overlapping relaxational contributions. In this work we investigate the frequency dependent conductivity and the dielectric properties of silver iodide–silver molybdate glasses in the mHz–GHz frequency range at temperatures between 300 K and 70 K, aiming in particular to ascertain whether a correlation can be found between the features of the dielectric response and the anomalous mechanical response of these fast ion conducting glasses.