RESEARCH OF THE ELECTRICAL PROPERTIES OF THE INTERCRYSTALLITE BOUNDARY AND MECHANISMS OF CONDUCTIVITY IN A ZnO VARISTOR WITH IMPURITIES
The article describes the electrical properties of the intercrystallite boundary and mechanisms of conductivity in a ZnO varistor with impurities. The study shows the properties of the reagents used in the synthesis of the ZnO varistor, as well as the composition of the substances used to provide the varistor effect. The article also presents the energy diagrams of the crystallite boundary in the ZnO varistor, the equivalent circuit diagram, and the energy diagram of microvaristors, respectively. It has been established that conductivity is possible during physical processes both at the intercrystallite boundary and through a potential barrier. And also, the dependence of conductivity on frequency and temperature was shown. It turned out that in the low-frequency region, the electrical conductivity increases monotonically, and then strongly increases with increasing frequency. In this case, the electrical conductivity s changes according to the law s≈f0.8. The resulting dependence s≈f0.8 indicates a hopping mechanism of charge transfer over states localized in the vicinity of the Fermi level . Dependence of conductivity on temperature, it can be said that the charge transfer in the varistors under study is carried out by hopping conduction of electrons with a variable hopping length over localized states lying in a narrow energy band near the Fermi level. These states in a varistor can be created by extended defects— intercrystallite boundaries and dislocations.
Keywords: ZnO varistors, impurities, potential barrier, crystallite, microvaristors, energy circuit, non-linearity, electrical conductivity, frequency, temperature.