Preparation and Nonlinear Conductivity Characteristics of Silicone Rubber Filled with Silver-Coated Tetrapod-Shaped ZnO Whiskers

Abstract

Tetrapod-shaped zinc oxide (T-ZnO) whiskers were coated with silver by chemical plating (T-ZnO@Ag). T-ZnO(T-ZnO@Ag)/silicone rubber composites were fabricated at a temperature of 165°C and pressure of 15 MPa. The nonlinear conductivity characteristics of T-ZnO (T-ZnO@Ag)/silicone rubber composites with volume fractions of 1 vol.%, 2.4 vol.%, 3.7 vol.%, and 5 vol.% were investigated. The dielectric properties of the composites at frequencies of 0.1 Hz to 10 MHz were analyzed. The conductivity of the T-ZnO/silicone rubber composite increased with the T-ZnO content, while the switching field decreased. Upon the coating of T-ZnO with Ag, the nonlinear characteristics of the T-ZnO@Ag/silicone rubber composite significantly enhanced. The nonlinear coefficient reached 10.95 at the filler content of 2.4 vol.%. The percolation threshold of T-ZnO fillers is significantly lower than that of spherical ZnO fillers. Percolation threshold and Schottky barrier effect were utilized to explain the nonlinear electrical properties.