Transition super ionic conductance

The value of the specific conductivity at room temperature is usually orders of magnitude smaller than in liquid electrolytes. For example, the ionic conductivity of NaCl at room temperature is of the order of 10 S cm". Conductivities with values almost as high as those for liquid electrolytes can nevertheless be achieved by increasing temperature. The transition from the region of low conductance at room temperature to super ionic conductance at higher temperature can occur continuously, as a transition of second-order, or as first-order transition, which is shown in Figure 1.10. 

Figure 1.10 Transition from room temperature ionic conductance to super ionic conductance, (a) Continuous, (b) second-order transition, and (c) first-order transition, critical transition temperature.

The transition to super ionic conductivity (y-AgJ) is observed at 147 °C (Figurel.21). At 137 °C the wurtzite lattice is formed. The wurtzite lattice transfers into the y-Form at 147 °C connected with a jump in conductivity from 10 to 1.3 S cm . This lattice consists primarily of a phase centered iodide lattice with a highly disordered Ag+ sublattice with very mobile Ag ions. The transition to super ionic conductivity is a first-order phase transition. 

Figure 1.21 Conductivity of Agl. Transition to super ionic conductivity and comparison to RbAg4lj. (Reproduced with permission from Ref. [37], CRC Press.)...

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