Effect of Ni and Cr on the stability of leakage current for spinel-reduced ZnO varistor ceramics

Abstract

With a new concept of reducing the spinel particles in ZnO varistor ceramics (ZVC), the molar ratio of Sb2O3 (M S)/Bi2O3 (MB) and the effect of the sintering temperature (TS) on densification behavior and varistor voltage (Vb: V1mA/mm) were investigated. The densification behavior of ZVC during the sintering process was significantly affected by the MS/MB, and the densification curve was shifted to a lower temperature with a decreasing MS/MB. Based on these experimental results, four types of spinelreduced ZnO varistor ceramics (SRZVC) were fabricated to investigate the effect of transition elements such as Ni and Cr on electric stability of the resistive leakage current (Ir). These experiments revealed that electric stability of Ir depended on the contained transition elements, and was influenced by the segregating of transition elements in spinel particles. © 2011 The Ceramic Society of Japan.