Effect of MnO_2 addition on microstructure and electrical properties of ZnO-V_2O_5-based varistor ceramics

摘要

The microstrueture and electrical properties of ternary system ZnO-0.5 mol percent V_2O_5-MnO_2 ceramics sintered were investigated in accordance with MnO_2 content by sintering at 900 deg C. For all samples, the microstructure of the ternary system ZnO-V_2O_5-MnO_2 ceramics consisted of mainly ZnO grain and secondary phase Zn_3(VO_4)_2. The incorporation of MnO_2 to the binary system ZnO-V_2O_5 ceramics was found to restrict the abnormal grain growth of ZnO. The breakdown field in the E-J characteristics increased from 175 to 992 V/cm with the increase of MnO_2 content. The incorporation of MnO_2 improved non-ohmic properties by increasing non-ohmic coefficient. The highest non-ohmic coefficient (27.2) in the ternary system ZnO-0.5 mol percent V_2O_5-MnO_2 was obtained for MnO_2 content of 2.0 mol percent.