ZnO microvaristors doped polymer composites with electrical field dependent nonlinear conductive and dielectric characteristics

Abstract

ZnO microvaristor/rubber composites with nonlinear conductive and dielectric properties were fabricated and investigated for the first time. The composites exhibit nonlinear conductive behaviors only when the filler concentration is above percolation threshold (39vol%), but show nonlinear dielectric properties with various filler concentration (viz. 30–60vol%). Both the nonlinear conductive and dielectric properties can be tuned by adjusting the filler concentration. Percolation threshold theory was utilized to explain the nonlinear electrical properties, and an internal barrier layer capacitor (IBLC) model was proposed to successfully explain the novel nonlinear dielectric properties, which demonstrates that the hole injection might be the key to the dramatic increase of the permittivity.