Novel mixed rare earths doped ZnO-Bi₂O₃-based varistor ceramics

Novel mixed rare earth Sc₂O₃ and Y₂O₃ doped ZnO-Bi₂O₃ based varistor ceramics were prepared by a solid reaction route, their electrical properties and microstructure were studied. The results show that mixed rare earth doping can improve the comprehensive performance of ZnO-Bi₂O₃ based varistor ceramics more remarkably than single rare earth doping, but the effect of mixed rare earth doping on their electrical properties is consistent with that of single rare earth doping. When the content of Sc₂O₃ is the same, the voltage gradient of mixed rare earth Sc₂O₃ and Y₂O₃ doped ZnO-Bi₂O₃ based varistor ceramics increases with the increase of the amount of Y₂O₃; when the content of Y₂O₃ is the same, the nonlinear coefficient of the varistor ceramics increases with the increase of the amount of Se₂O₃. After adding 0.12% Sc₂O₃ and 0.20% Y₂O₃ (molar fraction), mixed rare earth Sc₂O₃ and Y₂O₃ doped ZnO-Bi₂O₃ based varistor ceramics exhibit comparatively ideal comprehensive electrical properties:the threshold voltage is 410 V·mm^-1 the nonlinear coefficient is 38.0, and the leakage current is 0.58 μA.