Ionic conduction in KBr-KI mixed crystals

Ionic conductivity of KBr_1?xI_x (0 ? x ? 0.5) mixed crystals has been studied as a function of temperature in the range of 2 ionic conductivity and lowers the activation energy appreciably which is consistent with our earlier results on AgBr-AgI mixed crystals, and proposal that the purely elastic displacements (lattice strain) caused by the very “wrong size” of the substituent ions is primarily responsible for the behavior. The strain thus produced is expected to cause “lattice loosening” and hence lowering of the melting points (T_m) or the enthalpy of formation of the Schottky defects (H_s). A semiquantitative calculation shows this to be the case.