Effect of TiO2 doping on microstructure and electrical properties of ZnO-Bi2O3-based varistors

In this work, ZnO-Bi2O3-based varistors with different TiO2 doping amounts were prepared by traditional solidphase sintering method, and the effects of TiO2 doping on the microstructure and electrical properties of ZnOBi2O3-based varistors were investigated. The phase composition, microstructure, and element composition of ZnO varistors were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and energy dispersion spectrometer (EDS). A multifunctional lightning current impact generator and electrochemical workstation tested the comprehensive electrical performance of the ZnO varistors. The experimental results show that TiO2 doping can effectively improve the electrical properties of ZnO varistors. The electrical performance parameters of ZnO varistor with optimal TiO2 doping ratio (0.06 mol%) are voltage gradient E1 mA= 311 V & sdot;mm- 1, leakage current density JL= 0.87 mu A & sdot;cm- 2, nonlinear coefficient alpha= 21, residual voltage ratio K= 1.829, and aging coefficient Kct= 0.874, respectively. The U1 mA voltage under 4/10 mu s waveform after 100 kA high current impact is 97.34 % of the initial. The protection level and stability of Ti-Bi-O pre-synthesis products doped ZnO varistors after high current impact are further improved.