Effect of Dy_2O_3 addition on microstructure, electrical properties, and aging behavior of ZnO-V_2O_5-MnO_2-CoO varistor ceramics

摘要

The microstructure, electrical properties, and aging behavior of ZnO-V_2O_5-MnO_2-CoO-Dy_2O_3 varistor ceramics were investigated for different contents of Dy_2O_3. The microstructure consisted of ZnO grain as a main phase and secondary phases such as Zn_3(VO_4)_2, ZnV_2O_4, and DyVO_4. The average grain size increased from 7.6 to 10.1 μm and the sintered density slightly increased from 5.53 to 5.57 g/cm3 with the increase of Dy_2O_3 content. The varistor ceramics added with 0.05 mol% Dy_2O_3 exhibited the most nonlinear properties, with nonlinear coefficient of 30, and the highest stability against DC-accelerated aging stress. The Dy_2O_3 acted as an acceptor due to the decrease of donor density in the range of 2.73 × 10~18/cm~3 to 1.28× 10~18/cm~3.