Effect of sintering time on varistor properties of Dy2O3-doped ZnO-Pr6O11-based ceramics

The microstructure and electrical properties of the varistors, which are composed of ZnO-Pr6O11-CoO-Cr2O3-Dy2O3 (ZPCCD)-based ceramics, were investigated with different sintering times. The increase of sintering time led to more densified ceramics, whereas the deterioration of nonlinear properties. The highest nonlinearity was obtained from the varistor sintered for 1 h, with 55 in nonlinear exponent and 0.1 muA in leakage current. As sintering time is increased, the donor concentration and density of interface states were increased in the range of 1.06 x 10(18)-1.60 x 10(18)/cm(3) and 3.15 x 10(12)-3.67 x 10(12)/cm(2), respectively. However, the barrier height was decreased according to increasing sintering time. (C) 2004 Elsevier B.V. All rights reserved.