The Study of Microstructure and Electrical Property of Aluminium doped ZnO-based Varistor Materials

Abstract

In this work, the electrical properties of metal-doped ZnO-based varistor materials, prepared by sol-gel method and sintered at 1,150ºC for 2 h, were studied. ZnO-based varistor was doped with addition of 0.1, 0.3 and 0.5 mol% Al(NO₃)₃. The ZnO-based varistors with additives improved electrical properties. The non-linear coefficient (α) is in the range of 6.7 – 37, the breakdown field (E_B) is in the range of 6,298 – 6,496 V/cm, and the leakage current density (J_L) is in the range of 45.45 – 614.48 µA/cm². As a result, ZnO-based varistor with 0.1 mol% Al(NO₃)₃ exhibited excellent electrical properties with high non-linear coefficient (α = 37) and high breakdown field. The microstructure of ZnO-based varistor consisted of ZnO grain, spinel and Bi-rich phase confirmed by XRD and SEM techniques.