Effect of Bi2O3 doping on the electrical characteristics of Al-doped ZnO varistors with low residual voltage

The effects of Bi₂O₃ doping on the electrical characteristics of Al-doped ZnO varistors were studied. The electrical characteristics and the microstructural parameters of the varistor samples with various content of Bi₂O₃ additive were investigated. With the amount of the doped Bi₂O₃ increased, the leakage currents of the Al-doped ZnO varistors are inhibited obviously. In addition, their breakdown electric fields decrease and their nonlinear coefficients increase accordingly. The XRD patterns show that the Bi-rich phase changes remarkably in the varistor samples as the delta-Bi₂O₃ are decreasing and the BiO_2-x phase are increasing. The effects of Bi₂O₃ doping on the electrical characteristics of the Al-doped ZnO varistors are discussed based on the XRD patterns.