An ultralow concentration of Cr2O3 dopants driven lower temperature sintering ZnO-based varistor ceramics

Abstract

Low working voltage driven ZnO-based varistor ceramics play an important role in the multilayer chip varistors, which require a low sintering temperature of ZnO varistor for its low energy consumption. Herein a remarkable reduction of the sintering temperature from the usual 1100°C-1300°C to 950°C was successfully achieved in the ZnO ceramics via a certain 0.05 mole percent of Cr₂O₃ dopants. The underlying mechanism was found to be involved with the formation of basal-plane inversion boundaries between the ZnO grains, which can promote the rapid grain growth within the ceramics. Furthermore, the ZnO varistors with 0.05 mol% Cr₂O₃ dopant exhibited excellent performance. A low breakdown voltage of 416 V/mm, a high nonlinear coefficient of 39, and a low leakage current of 3.4 μA were obtained simultaneously. This work presents an effective and promising approach for the cost-efficient preparation of high-performance ZnO-based varistors, which has particular significance for the application of multilayer chip varistors with low working voltage.