Effect of laser shock wave on electrical property of ZnO varistor ceramics

In order to study the influence of laser shock on the electrical property of ZnO varistor ceramics, ZnO varistor ceramics was shocked by an Nd:YAG laser. Electrical parameters of ZnO varistor ceramics were measured with a CJ1001 varistor tester and morphology and microstructure of ZnO varistor ceramics was characterized by X-ray diffraction and scanning electron microscope. The experimental data of electrical property of ZnO varistor ceramics was obtained by laser shock process. The results indicate that after laser shock processing, the voltage gradient of ZnO varistor ceramics was reduced by 15.6%; its nonlinear coefficient substantially increased by 43.4% and leakage current reduced by 50%. Phase composition of ZnO varistor ceramics includes mainly ZnO main phase, Zn2.33Sb0.67O4 phase and -Bi2O3 phase in high-temperature sintering. However, it include not only the former three phases, but also the new phase -Bi2O3 phase after laser shock process. The emergence of the new phase is the main cause for change of the electrical property of ZnO varistor ceramics.