Microstructure and electrical properties of ZrO2-doped ZnO varistor ceramics

The microstructure and electrical properties of ZnO varistor ceramics with different ZrO2 content prepared by a solid reaction route and sintered at 1100 °C were investigated. The microstructures of the varistor ceramics samples were characterized by X-ray diffraction and scanning electron microscopy; the electrical properties and current–voltage (V–I) characteristics of the varistor ceramics were investigated by DC parameter instrument. The microstructure of the prepared samples shows a decrease in grain size of ZnO phase with the ZrO2 content increase. ZrO2-doped ZnO varistor ceramics exhibit comparatively vastly superior comprehensive electrical properties with addition of 0.50 mol% ZrO2, such as the threshold voltage is 350 V/mm, the nonlinear coefficient is 25.4 and the leakage current is 2.96 μA.