Effect of fabrication processes on the properties of ZnVSb based varistor ceramics

The sintering characteristics, microstructure and properties of ZnVSb based varistor ceramics were studied for three fabrication processes. Based on the examinations on the density, microstructure and electrical characteristics of the ceramics synthesized by the process involving a pre-heat-treatment of V₂O₅/Sb₂O₃ mixture of specific ratio, the process of substituting SbVO₄ for Sb₂O₃ before fabrication and by the traditional oxide ceramic synthesizing process, a gradual increase of spinel formation within the ceramics, and the segregations of dopant element within the vicinity of ZnO grain boundaries were observed. These micro structural-changes within the ceramics contribute to the formation of higher grain boundary barrier which naturally leads to increasing the nonlinearity and break down voltage of the ceramics. The result of this study unveils a new way of tailoring the properties of ZnVSb based varistor ceramics according to application requirements.