The effect of pre-synthesized V₂O₅/Sb₂O₃ powder content on the characteristics of ZnO-V₂O₅ based varistor ceramics

Antimony doped ZnO-V₂O₅ varistor ceramics were synthesized at 950°C by traditional electronic ceramic fabricating method with a modification in pre-calcining Sb₂O₃ with V₂O₅. By this two step fabrication, the hindering effect of Sb₂O₃ on the grain growth of ZnO grains, caused by its volatilization and re-coagulation on the surface of growing zinc oxide grains during the sintering process, could be avoided, by which the low temperature sintering of the ceramic is greatly promoted. As the content of presynthesized V₂O₅/Sb₂O₃ compound increases, V_Zn typed acceptors increase due to the way to add Sb into the ceramics in form of V₂O₅/Sb₂O₃, resulting in more substitutions of Sb³⁺ cation for Zn²⁺ cation. This finally contributes to the higher grain boundary barrier height and the better current-voltage nonlinearity of the ceramics. The optimum properties of the ceramic, with relative density >98%, nonlinearity exponent α > 50, could be achieved, the ceramic's potential in producing multilayer varistor is reasonably promoted.