Microstructure and electrical properties of Lu2O3-doped ZnO-Bi2O3-based varistor ceramics

Lu2O3-doped ZnO-Bi2O3-based varistor ceramics samples were prepared by a conventional mixed oxide route and sintered at temperatures in the range of 900-1 000 °C, and the microstructures of the varistor ceramics samples were characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM); at the same time, the electrical properties and V-I characteristics of the varistor ceramics samples were investigated by a DC parameter instrument for varistors. The results show that the ZnO-Bi2O3-based varistor ceramics with 0.3% Lu2O3 (molar fraction) sintered at 950 °C exhibit comparatively ideal comprehensive electrical properties. The XRD analysis of the samples shows the presence of ZnO, Bi-rich, spinel Zn7Sb2O12 and Lu2O3-based phases.