Effect of Na2O and B2O3 Addition on Nonlinear Electrical Properties of WO3-Based Capacitor–Varistors

摘要

WO3-based varistors with added Na2O and B2O3 were synthesized by the solid-state reaction. The undoped and B2O3-doped WO3 ceramics exhibited weak nonlinear I-V characteristics. The nonlinear I-V characteristics of the ceramics increased slightly after the addition of Na2O and more significantly after the addition of Na2O and B2O3. The nonlinearity coefficients α of the WO3, Na0.005WO3, and Na0.005WO3-5 wt % B2O3 ceramics were 1.86, 2.03, and 5.22, respectively. The breakdown voltages of the WO3, Na0.005WO3, and Na0.005WO3-5 wt % B2O3 ceramics were 1.56, 6.05, and 12.42 V/cm, respectively. The dielectric constant and the dielectric loss of the Na0.005WO3-5 wt % B2O3 ceramic were ~50-150 and less than 0.3, respectively, for frequencies ranging from 1 to 1000 kHz.