Dielectric and varistor properties of rare-earth-doped ZnO and CaCu_3Ti_4O_(12) composite ceramics

摘要

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 CaCu_3Ti_4O_(12) (TCCTO) powders by chemical co-precipitation and sol-gel methods respectively, and then obtained the TCCTO/ZnO composite ceramics, sintered at 1100℃ 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 CaCu,Ti_4O_(12)(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.