Fast ion transport in silver halide solid solutions and multiphase systems

The incorporation of homovalent ions, e.g., I− in AgBr, leads to a substantial increase in ionic conductivity σ. The charge compensation concept does not explain the enhancement. AgBr+30 mol. % AgI exhibits σ∼7 Ω−1 cm−1 at 380 °C, which is ∼170% larger than that of α-AgI, the best known supersonic conductor, at its melting point. The purely elastic displacement caused by the foreign ion is suggested to be the origin of such a unique behavior. Furthermore, AgI-AgBr two-phase systems display σ∼103 times higher than predicted by the classical theories.