Two-step method fabricating high nonlinearity ZnVSb based varistors

A two-step method was introduced to fabricate ZnO-V₂O₅-Sb₂O₃ (ZnVSb) based varistor at low temperatures, such as 900-950 °C. Sb₂O₃/V₂O₅ (V/Sb) precursor was first synthesized and then used to replace Sb₂O₃ as one of the main dopants. The effect of its concentration on the microstructure and electrical properties of the ZnVSb based ceramic was investigated at doping levels up to 1.5 mol%. The microstructural homogeneity of the ceramic was greatly improved by the addition of the precursor. With increasing V/Sb precursor, the average grain size decreased, while the nonlinearity of the as sintered ceramic was enhanced (α_Max = 89). The ZnVSb ceramic is a promising material in the fabrication of multi-layered varistor, in which it could be co-sintered with pure Ag inner electrode.