Effect of Sb addition on the Electrical Characteristics of Bi-based ZnO Varistors Containing Zr and Y

The effects of adding Sb to a Bi-Mn-Co-Si-Cr-Ni-Y-Zr-added ZnO varistor (with the same composition as a commercial varistor) on the varistor voltage, leakage current, and resistance to electrical degradation were investigated. Bi is incorporated in spinel particles, and delta-Bi2O3 eventually disappears with the addition of small amounts of Bi, especially as the amount of Sb2O3 added increased. Reduction in both the nonlinearity index and the amount of delta-Bi2O3 for small amounts of added Bi with the addition of more than approximately 1.25 mol% Sb2O3 demonstrates that Sb inhibits Bi2O3 from forming deep interfacial impurity levels at the grain boundaries. The sample containing 1.2 mol% Bi2O3, 1.0 mol% ZrO2, 1.0 mol% Y2O3, and 1.5 mol% Sb2O3 added exhibits a high varistor voltage (approximately 630 V/mm), high resistance to electrical degradation and low leakage current.