Effects of Sb, Zr, and Y addition on the electrical characteristics of Bi-based ZnO varistors

Abstract

The effects of adding Sb, Zr, and Y to a Bi–Mn–Co–Si–Cr–Ni-added ZnO varistor (with the same composition as a commercial varistor) on the varistor voltage, leakage current, and resistance to electrical degradation were investigated. Both the varistor voltage and the nonlinearity index of the voltage–current characteristics a before electrical degradation for samples added 1.0 mol% ZrO2 and 1.0 mol% Y2O3 were maximized at approximately 1.0 mol% Sb2O3 and decreased rapidly when the amount of Sb2O3 exceeded more than about 1.0 mol%. Samples added 1.0 mol% ZrO2, and 1.0 mol% Y2O3, and less than 0.75 mol% Sb2O3 had a comparable leakage current to samples added neither ZrO2 nor Y2O3. Sb is an important element that is necessary to obtain a high varistor voltage, a low leakage current, and an excellent resistance to electrical degradation. However, the same varistor voltage can be obtained by adding Y and reducing the amount of Sb2O3 added.

High Nonlinearity and High Voltage Gradient ZnO Varistor Ceramics Tailored by Combining Ga2O3, Al2O3, and Y2O3 Dopants

“…The least residual voltage value (1.60) is suitable for 800 kV direct currents and 1000 kV alternate currents whose switching impulse protective levels are in the range of 1.85 or even less . The increase in the leakage current is attributed to willemite and Y 2 O 3 ‐containing phases at the grain boundaries of ZnO when the concentration of Ga dopants exceeds 0.6 mol% …”

“…13 The increase in the leakage current is attributed to willemite and Y 2 O 3 -containing phases at the grain boundaries of ZnO when the concentration of Ga dopants exceeds 0.6 mol%. 1,8 The X-ray diffraction patterns of samples doped with various amounts of Ga are shown in Fig. 4.…”

“…2,3 For the fabrication of high voltage gradient varistors, one common method is to decrease the grain size. 3,4 It has been reported that the voltage gradient can be dramatically improved by the introduction of rare-earth oxides to a Bi-based ZnO varistor; [5][6][7] however, the leakage current increases, 8 which deteriorates the life performance of varistors. 7 The deteriorated life performance of ZnO varistors, which are the core elements of surge arresters, is a potential danger to power grid security.…”

Optimization of Bi2O3, TiO2, and Sb2O3Doped ZnO-Based Low-Voltage Varistor Ceramic to Maximize Nonlinear Electrical Properties

“…However, with more increasing beyond optimum levels the alpha values decreased. This reduction may be attributed to the decrease in the amount of Bi 2 O 3 since Bi is incorporated into spinel particles till Bi 2 O 3 ultimately fades as the amount of Sb 2 O 3 enhanced [ 32 ].…”