Fabrication of Bismuth-based Zinc Oxide Varistors with High Varistor Voltage by Addition of Tin and Yttrium Oxides

摘要

The effects of the addition of tin oxide (SnO_2) and yttrium oxide (Y_2O_3) to bismuth (Bi)-manganese (Mn)-cobalt (Co)-silicon (Si)-chromium (Cr)-nickel (Ni)-added zinc oxide (ZnO) varistors (a basic varistor) on the varistor voltage, resistance to electrical degradation, and leakage current were investigated. The addition of SnO_2 increased both the varistor voltage and the resistance to electrical degradation. However, simultaneous addition of both SnO_2 and Y_2O_3 increased the varistor voltage but the resistance to electrical degradation deteriorated. ZnO varistors with varistor voltage over approximately 520 V/mm, excellent resistance to electrical degradation, and low leakage current could be obtained by adding SnO_2 with Sn02-to-ZnO molar ratio of approximately 1:10 to the basic varistor.