Fabrication of High Performance Multilayer ZnO Varistors with Chemically Synthesized Doped Zinc Oxide Powder

Abstract

Two types of multilayer ZnO varistors are prepared by the chemically synthesized (CS) powder and the mixed oxide (MO) powder. The ceramic microstructure analysis shows that the multilayer variestor (MLV) ceramic prepared by the CS powder has the fine grain, the homogeneous distribution of grain size and the uniform dopant distribution. The CS powder prepared multilayer ZnO varistors display better electrical properties, including higher nonlinear coefficient, higher breakdown voltage, higher peak current, lower leakage current and lower clamping voltage, than those made by the mixed oxide powder. All these superior electrical properties are attributed to the CS powder, which makes more uniform dopant distribution throughout the multilayer ZnO varistors. The homogeneous distribution for the various dopants in the varistor ceramic has been achieved by the chemically synthesized doped ZnO powder. Therefore, the chemically synthesized powder can be used in the manufacture of high performance multilayer ZnO varistors.