Transformation-Range Viscosities and Thermal Properties of AgI-Based Superionic Glasses

Abstract

Differential scanning calorimetric measurements were performed for the superionic glasses in the systems AgI-Ag₂O-M_xO_y (M_xO_y=B₂O₃, GeO₂, P₂O₅, MoO₃). Since the heat capacity change (ΔC_p) in glass transition was decreased with an increase in the AgI content in all of the systems, the fragility seemed superficially to be decreased with the AgI content from a viewpoint of ΔC_p. Transformation-range viscosities were also measured for the same glasses above by using a beambending method. The fragility was not changed with an increase in the AgI content from a viewpoint of E_η/T_g, where E_η and T_g are respectively the activation energy for viscous flow and the glass transition temperature. It is thus concluded that only network part in the glass structure contributes to the value of ΔC_p and thus the decrease of ΔC_p with increasing AgI content is caused by the fact that the portion of the glass network is decreased with increasing AgI content.