Nickel oxide doping effects on electrical characteristics and microstructural phases of ZnO varistors with low residual voltage ratio

Abstract

The effects of nickel oxide (Ni₂O₃) additives on electrical characteristics and microstructural phases of ZnO varistors with low residual voltage ratio are studied. The breakdown electrical fields increase remarkably with the amount of the doped nickel oxide increased. The minimum of the residual voltage ratios of the samples reaches 1.39. While the amount of the doped nickel oxide is more than 2 mol %, a new phase of chrombismite Bi₁₆CrO₂₇ is observed from X-ray diffraction (XRD) and scanning electron microscopy (SEM). The δ-Bi₂O₃ phase decreases and the BiO_2−x phase increases correspondingly. In addition, the capacitance versus voltage (C–V) characteristics of the samples are measured and analyzed.