Dielectric and varistor properties of rare-earth-doped ZnO and CaCu3Ti4O12 composite ceramics

Abstract

To investigate the multi-functional ceramics with both high permittivity and large nonlinear coefficient, we have prepared rare-earth Tb -and- Co doped ZnO and TiO 2-rich CaCu3Ti4O12 (TCCTO) powders by chemical co-precipitation and sol–gel methods respectively, and then obtained the TCCTO/ ZnO composite ceramics, sintered at 1100°C for 3 h in air. Analyzing the composite ceramics of the microstructure and phase composition indicated that the composite ceramics were composed of the main phases of ZnO and CaCu3Ti4O12 (CCTO). Our results revealed that the TCCTO/ ZnO composite ceramics showed both high dielectric and good nonlinear electrical behaviors. The composite ceramic of TCCTO: ZnO = 0.3 exhibited a high dielectric constant of ~210(1 kHz) with a nonlinear coefficient of ~11. The dielectric behavior of TCCTO/ ZnO composite could be explained by the mixture rule. With the high dielectric permittivity and tunable varistor behaviors, the composite ceramics has a potential application for the higher voltage transportation devices.