UNUSUAL TRANSPORT AND STRUCTURAL-PROPERTIES OF MECHANICALLY TREATED POLYCRYSTALLINE SILVER-IODIDE .2. DIELECTRIC-PROPERTIES

Dielectric properties of mechanically treated AgI are studied within t he frequency range 20 Hz-l MHz. Contribution of the electrode polariza tion was eliminated and the dielectric permittivity of polycrystalline AgI was extracted. Dielectric properties of mechanically treated AgI are typical of relaxer ferroelectrics with low-frequency dielectric co nstant epsilon(s)/epsilon(0) ranging from 30 to 200 and high-frequency limit epsilon/epsilon(0) = 8+/-2 close to the dielectric constant of beta-AgI single crystals. Non-linear correlation between conductivity and epsilon(s) holds, ageing or heating lead to decrease of the both. Results are interpreted by formation of polytypes due to the mechanica l treatment. The polytypes formed seem to be electrically active. High values of epsilon(s) are assumed to be caused by polarization of spac e charges accumulated on boundaries of electric domains existing in th e polytypes.