THERMALLY STIMULATED DEPOLARIZATION CURRENTS IN NICKEL DOPED NACL-CRYSTALS

Depolarization currents have been investigated for thermally and mecha nically pretreated NaCl crystals doped with divalent nickel ions. The models of Debye and Maxwell-Wagner-Sillars polarizations have been exp loited to describe the behavior of ITC bands detected below (dipolar), near and above (interfacial) room temperature, respectively. The NaCl :Ni2+ system was especially interesting for kinetic studies because th e dopant ions are distinctly smaller than the matrix cations. It has b een found that the precipitation phenomena can be understood in terms of an Avrami-approach of the process mainly occurring in the stress fi elds of dislocations. The migration of impurities is controlled by the diffusion of cation vacancies.