Jun Wang,Xilin Wang,Youwei Yao,Juyi Guo,Xiaogang Ouyang,Zhidong Jia
The application of polymer composites with electric field dependent nonlinear conductive and dielectric characteristics for high voltage equipment is an effective method to control electric field stress and disperse space charges. In this study, core-satellite CaCu3Ti4O12@ZnO fillers were synthesized and doped into silicone rubber composites, and compared to a mixture of CaCu3Ti4O12 and ZnO with the same filler concentration. The composites exhibited both nonlinear conductive and nonlinear dielectric properties with nanoparticle fillers for the first time. Both the nonlinear conductive coefficient and dielectric coefficient increased with filler concentration. The classical current-path model was utilized to explain the nonlinear conductive properties, while the interface-barrier-layer-capacitor model and double-depletion-layer model were introduced to explain the nonlinear dielectric properties, which would broaden the thinking for the fabrication of nonlinear composites.
Tuning the electrical heterogeneity of CaCu 3 Ti 4 O 12 (CCTO) ceramic is extremely important to improve its properties. In this work, the CCTO ceramics with enhanced dielectric and nonlinear properties were obtained by the introduction of nano ZnO based on the electrical heterogeneity modulation strategy. As a result, all the CCTO-ZnO samples show the colossal dielectric constant of 10 4 –10 5 at room temperature. Meanwhile, the dielectric constant of CCTO-ZnO samples exhibits better stability in a wide frequency range from 10 1 Hz to 10 5 Hz and over a temperature scope of 30–210 °C. Most importantly, the x = 0.04 sample presents a relatively lower room-temperature dielectric loss of about 0.07 at 10 3 Hz. Furthermore, the breakdown field strength accompanied by the nonlinear coefficient of CCTO-ZnO ceramics is also improved. The enhancement of dielectric and nonlinear behaviors in these ceramics is mainly ascribed to the tunable electrical heterogeneity as per the internal barrier layer capacitor (IBLC) model.
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