Schematic representation of conductivity variation as a function of temperature. Below T g , charge carrier formation and migration are both activated mechanisms. Above T g , charge carrier formation remains activated but its migration, correlated with chain movements, follows a VFTH dependence on temperature.
σT product as a function of temperature in Arrhenius coordinates for five compositions of the xAgI(1 − x)AgPO3 system. Open symbols represent experimental data from Malugani et al.,4 and solid symbols represent data from Pathmanathan et al. 7
Activation energy (E A ), charge carrier formation (ΔH f ) (as shown in Table I), and migration (ΔH m ) enthalpies as a function of composition in the glass system xAgI(1 − x)AgPO3. E A is deduced from conductivity data4 below T g . ΔH m is calculated by the difference as expressed in Eq. (10). The solid lines serve as visual guides.
Room temperature mobility μ + calculated in this work from conductivity data and Eqs. (2) [●] and (3) [▲] and measured by the ionic Hall effect35 [■], for xAgI(1 − x)AgPO3 glasses.
Ionic conductivity of the glass system xAgI(1 − x)AgPO3 at 25 °C. Symbols represent experimental data from Malugani et al. 4 The solid line represents the expected variation from a regular solution model (see text) with α = 81.5 kJ mol−1.
Activation energy for conduction in the glass system xAgI(1 − x)AgPO3. The symbols represent experimental data from Malugani et al. 4 The solid line corresponds to the expected variation from a regular solution model (see text) with α = 82 kJ mol−1.
Parameters A and T 0 and numerical values for ΔH f and B determined by the best fit of experimental data over the glass transition temperature, using Eq. (9). The values of the pre-exponential term A are determined by extrapolation of σT below T g using data from Malugani.4 T 0 are calculated by (T 0 = 3/4 T g ) based on T g data from Ref. 15. The corresponding number of experimental data points N and χ2 values are also indicated. The mathematical accuracy is ±10−2 eV and 3 × 10−3 eV for ΔH f and B, respectively. x is the AgI molar ratio in the xAgI(1 − x)AgPO3 glass system.
Density (from Ref. 24), total silver cation concentration, n, calculated from density data, (n +/n) ratio, experimental conductivity, σ, and calculated (Eqs. (1) and (2) or Eq. (3)) mobility μ + at 25 °C, for the xAgI(1 − x)AgPO3 glasses.
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