Nonlinear Electrical Characteristics of Antimony and Copper Doped Tin Oxide Based Varistor Ceramics

The novel CuO-doped dense tin oxide varistor ceramics are investigated. The densification of tin oxide varistor ceramics could be greatly improved by doping copper oxide additives. The introduction of antimony additives into a SnO₂.CuO ceramic system would make it possess excellent nonlinearity. The sample doped with 0.05mol% Sb₂O₃ possesses the highest nonlinearity coefficient (α=17.9) and the lowest leakage current density (J_L=52μA cm^-2) among all the samples. A modified defect barrier model is introduced to explain the formation of the grain-boundary barrier. The nonlinear behaviour of (Cu, Sb)-doped SnO₂ varistor system could be explained by the barrier model.