Effect of Zn7Sb2O12 pre-synthesis on microstructure and properties of ZnO varistor ceramics

Abstract

In this work, the Zn7Sb2O12 spinel phase is pre-synthesized at 980, 1000, 1020, 1040, and 1060 °C by mixing ZnO and Sb2O3 in a molar ratio of 7:1. ZnO varistors are prepared by replacing Sb2O3 with the Zn7Sb2O12 spinel phase. The effect of the Zn7Sb2O12 spinel on the electrical properties and microstructure of ZnO varistors is studied. The results show that Sb2O3 can produce free electrons and reduce the number of oxygen vacancies (VO⋅⋅) and grain size during the reaction process. The ZnO varistors prepared by replacing Sb2O3 with the Zn7Sb2O12 spinel phase have full grain growth and high density. In addition, ZnO varistors prepared by the Zn7Sb2O12 spinel phase replacing Sb2O3 can not only reduce the sintering temperature by 60 °C but also reduce the reverse voltage gradient rate of ZnO varistors from 7.85% to 1.2% on the basis of stable electrical properties and improve the impact stability of ZnO varistors. This method has the advantages of no change in formula composition and being a simple process and can provide ideas for the preparation of multilayer chip ZnO varistors.