Electrical And Microstructure Properties Of Y₂O₃-doped ZnO-based Varistor

ZnO varistors with highly nonlinear voltage-current characteristic excellent surge withstanding capability and wide range working stability are employed to protect electrical circuits in the fields of electrical and electronics. And the research to manufacture ZnO varistor with high voltage-gradient has attracted lots of attention both at home and abroad, and has prominent meaning in the future too. In this paper, the influence of Rare-earths oxide Y₂O₃ introducing to ZnO ceramics on the electrical and microstructure properties of varistor was studied. The varistor ceramics were prepared using high -energy ball milling (HEBM) technique under low temperature sintering, with voltage -gradient of 2197 V/mm.Firstly the influence of sintering temperature and ball milling time on the electrical properties , density or undoped Y₂O₃ ZnO -based varistor were researched . The results show that it is an effective method for acquiring better electrical properties that the powder were milled for 5h in ethanol .The crystallite size of the constituent oxides were refined to 43nm , the average particle size was 0.605μm and the powder more pure ( Fe%=0.78wt% ). In addition, the method of powder mixtures made by HEBM decreased 100℃--250℃ by contrast the sintering temperature of 1000℃.The constituent oxides were prepared by milling for 5h synthetic Bi₂O₃ and Sb₂O₃ powder which were firstly milled for 12h together. The ZnO-based varistors are produced by sintering at 1000℃: the leakage current of 3.0μA, the nonlinear coefficient of 22, the voltage gradient of 1516 V/mm. The constituent oxides were prepared by milling for 5h synthetic Bi₂O₃ and Sb₂O₃ powder which were produced by co precipitation process firstly together. The ZnO-based varistors are produced by sintering at 1000℃: the leakage current of 9.13μA, the nonlinear coefficient of 18.7, the voltage gradient of 1696 V/mm.Then the influence of sintering temperature and ball milling time on the electrical properties , density or doped Y₂O₃ ZnO -based varistor were researched . Y₂O₃-doped ZnO-based varistor ceramics were prepared using high-energy ball milling (HEBM) technique under low-temperature sintering, with voltage-gradient (V_1mA/mm) of 1934-2197 V/mm, non-linear coefficient (a) of 20.8-21.8, leakage current (I_L) of 0.59-1.04 μA and density of 5.46-5.57g/cm³ã€‚ XRD verified the existence of ZnO,...