Effects Of Co-doped On The Electrical Properties Of Ternary ZnO Varistor

The zinc oxide varistor is a new type of semiconductor resistor, because thesensitivity of the conduction effective absorption of over-voltage to achieve thepurpose of protecting the circuit and the cost is very low, low residual voltage,low leakage currentvoltage coefficient of the many advantages of the nonlinearindex of large, contemporary zinc oxide varistors are widely used in many fields,such as power generation systems, electronic circuit systems, home appliancesand other equipment, because absorbed the surge performance, especially maincharacteristics of the over-voltage protection, therefore, is the most widely usedvaristors.This same course of development of zinc oxide varistors, the varistorgeneration and conductive mechanism, a simple narrative, and through thetraditional preparation process, preparation of different concentrations of Co2O3doped zinc oxide varistor. Doped with different concentrations of cobalt, zincoxide varistor, the most important oxide additives Bi2O3content of differentconcentrations of zinc oxide varistors test in the region of low current sensitivityof electrical the difference in performance, as well as on each of the majorparameters. And a simple analysis of the microstructure of different samplesusing X-ray diffraction and scanning electron microscopy, and discuss mixedwith different concentrations of Co2O3case, the microscopic structure of Bi2O3and ZnO varistors.The experimental results are show on that: With the incorporation graduallyincreased the Co2O3share of the mole percentage content gradually increased,the varistor voltage, nonlinear coefficient become larger, the leakage current isdecreased, the dielectric constant and dielectric loss decreased, the conductance.The rate decreased gradually. And Co element incorporation during the sinteringprocess and the highly volatile Bi2O3solid solution at the grain boundaries, inhibiting its volatile. In addition, the microstructure also will change the asCo2O3concentration increases, the smaller grain size of ZnO, the densification isenhanced, the interplanar spacing gradually decreases, the diffraction competegradient, the diffraction peak the intensity decreases, the FWHM increase,variation of C-axis preferred orientation of the property. This study content forthe application of zinc oxide varistors have practical significance.