The influence of surfactant on ZnO varistors

ZnO varistors with and without surfactant such as sodium dodecyl sulphate (SDS) are prepared by nitrate-combustion process. The samples were identically heat treated and sintered at 1000 °C for 12 h to study the influence of the surfactant on the nonlinear electrical properties of polycrystalline ZnO. It is observed that the nonlinear coefficient decreases marginally (α = 35) for samples prepared with surfactant, whereas breakdown field (EB = 130 V/mm) decreased significantly. The corresponding parameters for the samples synthesized without surfactant are α = 45 and EB = 400 V/mm. Hence, this method can be used for the manufacture of varistors with low to moderate breakdown fields.