Nonlinear electrical properties and dielectric properties of ZnO ceramics doped with K2CO3

ZnO ceramics with different amounts of K2CO3 from 0.0 to 1.0 mol% are prepared by traditional solid-state sintering technique. The K2CO3-doping effects on the microstructure, nonlinear electrical properties and dielectric properties of ZnO ceramics are investigated. The grain size of ZnO ceramics increases from 0.9 to 1.5 mu m with increasing K2CO3 content. The leakage current density versus electric field characteristics indicate that ZnO ceramic samples exhibit similar nonlinear electrical properties. The switching field and nonlinear coefficient decrease in the range of 246.2 to 1.3 V/mm and 5.3 to 2.4 with the increase of K2CO3 content. The varistor voltage decreases from 344.9 to 2.0 V/mm, while the leakage current increases from 323.0 to 646.1 mu A. Meanwhile, as K2CO3 content increases, the dielectric constant and dielectric loss of ZnO ceramics are improved in the frequency range from 10(2) to 10(6) Hz at room temperature.