Influence of Bi_2O_3 Doping on Microstructure and Electrical Properties of ZnO-V_2O_5-MnO_2-Nb_2O_5 Varistor Ceramics

摘要

This article is a report on the effect of Bi_2O_3 addition on microstructure and electrical properties of ZnO-V_2O_5-MnO_2-Nb_2O_5 varistor ceramics. The average grain size increased from 5.6 to 7.2 μm as the Bi_2O_3 amount increased. Increasing the amount of Bi_2O_3 decreased the breakdown field from 4874 to 2205 V/cm. The ceramics doped with 0.025 mol% Bi_2O_3 exhibited a surprisingly high nonlinear coefficient (α = 60) and very low leakage current density (J_L = 20 μA/cm~2). In addition, when the Bi_2O_3 amount increased, the donor concentration increased in the range of 2.38 × 10~(17) - 8.17 × 10~(17) cm ~(-3) and the barrier height exhibited the highest value (1.12 eV) at 0.025 mol% Bi_2O_3.