Effect of plastic deformation on ionic conduction in pure AgI and AgI-Al2O3 composite solid electrolytes

The ionic conductivities of pure silver iodide and silver iodide-( 10-40 mol%) alumina composites used as solid electrolytes are determined at room temperature by a.c. impedance spectroscopy as a function of compression pressure and annealing temperature. The ionic conductivities of both the pure and the composite silver iodide specimens increase with increasing compression pressure. This suggests that structural defects acting as conduction paths are generated in abundance by the plastic deformation. The mechanical strength of the as-deformed pure silver iodide specimen is decreased drastically by annealing at 413 K, whereas that of the as-deformed composite specimens remains virtually unchanged. This indicates that the deformation-induced defects are present largely as dislocations. The ionic conductivity of the as-deformed pure silver iodide specimen determined during annealing at 323 K decreases with annealing time, whereas the conductivities of the as-deformed composite specimens are practically unchanged. It is concluded that the removal of the deformation-induced dislocations during annealing is impeded by dispersed alumina particles.