Effects of Eu2O3 doping on microstructural and electronic properties of ZnO-Bi2O3-based varistor ceramics prepared by high-energy ball milling

ZnO-Bi 2 O 3 -based varistor ceramics doped with Eu 2 O 3 in a range from 0 to 0.4% were obtained by high-energy ball milling and fired at 900–1 000 °C for 2 h. XRD and SEM were applied to determine the phases and microstructure of the varistor ceramics. A DC parameter instrument was applied to investigate the electronic properties and V - I characteristics. The XRD analysis of Eu 2 O 3 -doped ZnO-Bi 2 O 3 -based varistor ceramics shows that the ZnO, Eu-containing Bi-rich, Zn 7 Sb 2 O 12 -type spinel and Zn 2 Bi 3 Sb 3 O 14 -type which is the pyrochlore phase are present. With increasing Eu 2 O 3 content, the average size of ZnO grain firstly decreases and then increases. The grain boundary defect model was particularly used to explain the excellent nonlinearity of ZnO-Bi 2 O 3 -based varistor ceramics with the addition of 0.1 % Eu 2 O 3 and sintered at 950 °C.