The nonlinear properties and stability of ZnO-Pr6O11-CoO-Cr2O3-Er2O3 ceramic varistors

The nonlinear properties and stability of ZPCCE-based varistors, which are composed of ZnO-Pr6O11 -CoO-Cr2O3-Er2O3 ceramics, were investigated with Er2O3 content in the range of 0.0-4.0 mol%. Among ZPCCE-based varistors, the varistors with 2.0 mol% Er2O3 exhibited the best performance in terms of the densification, nonlinearity, and stability. The density of sintered ceramics was found to be 5.74 g/cm(3), which is 99.3% of theoretical density. The nonlinearity was characterized by 47.15 in the nonlinear exponent and 2.25 muA in the leakage current. They also showed very high stability, in which the variation rate of varistor voltage, nonlinear exponent, and leakage current is -0.15%, -3.56%, and -19.56%, respectively, under more severe continuous DC stress, such as (0.80 V-1 (mA)/90 degreesC/12 h) + (0.85 V-1 (mA)/115 degreesC/12 h) + (0.90 V-1 (mA)/ 120 degreesC/12 h) + (0.95 V-1 (mA)/135 degreesC/12 h). (C) 2001 Elsevier Science B.V. All rights reserved.