Zr, Y, Sb添加のZnOバリスタの課電劣化への影響

抄録

The effects of amount of Sb added to Bi-Mn-Co-Sb-Si-Cr-Ni-Zr-added ZnO varistors on the tolerance characteristics of electrical degradation were investigated. Furthermore, the effects of addition of both Zr and Y to Bi-Mn-Co-Sb-Si-Cr-Ni-added ZnO varistors (the same composition as one of commercial varistors) on the varistor voltage and leakage current were investigated. It was found that addition of Sb enhances the tolerance characteristics to the electrical degradation and the amount of Sb₂O₃ addition of approximately 1 mol% is the optimal. When the amount of added Sb increased, the amount of existence of a Zn_2.33Sb_0.67O₄-type spinel particle increased, because the amount of existence of Zr compound increased similarly. It was suggested that Zr compound was also related to the electrical degradation characteristic. Varistor voltage decreases a little when the amount of added Zr increases in simultaneous addition of Zr and Y. On the other hand, the value of nonlinear index α hardly changed. Without Zr, the increase in the leakage current accompanying the increase in the amount of added Y, which has been reported conventionally, was not found in this study. However, adding Zr of approximately 0.2 - 0.45 mol%, the leakage current increased by adding Y more than 1 mol% and adding Zr of approximately 0.6 mol%, it decreased.