Heat capacities and ac conductivities of AgI-based fast ion conducting glasses of AgI-${\mathrm{Ag}}_2$O-${\mathrm{P}}_2$${\mathrm{O}}_5$ and AgI-${\mathrm{Ag}}_2$O-${\mathrm{B}}_2$${\mathrm{O}}_3$ systems with different P-O or B-O network structures but with the same AgI concentration of 1.55×${10}^4$ mol ${\mathrm{m}}^{\mathrm{-}3}$ were measured in the temperature range 14–400 K and in the temperature and frequency ranges 100–200 K and 10 Hz–1 MHz, respectively. The β-glass transition due to a freezing-in of the rearrangement of ${\mathrm{Ag}}^{+}$ ions was observed by adiabatic calorimetry for the glasses in the liquid-nitrogen temperature region, and the conductometry was suggested to see the same mode of ${\mathrm{Ag}}^{+}$-ion motion as the calorimetry. It was found that the development of the network structure of the glass former at constant AgI concentration resulted in the decrease of the β-glass transition temperature and the activation energy for the diffusional motion of ${\mathrm{Ag}}^{+}$ ions and in the increase of the heat-capacity jump associated with the glass transition. The results support the amorphous AgI aggregate model for the structure of the conductive region in the glasses with relatively high AgI compositions, indicating that ${\mathrm{Ag}}^{+}$-ion conductivity is mainly dominated by the degree of development of the AgI aggregate region dependent on the glass-former network structure as well as the AgI composition.

• Received 29 November 1994

DOI:https://doi.org/10.1103/PhysRevB.52.3234