Abstract
Large dielectric constant (ε′) and high breakdown strength (Eb) polymer dielectrics with low loss are predominant in energy storage and power systems. In this work, an insulating shell of alumina (Al2O3) was constructed on the surface of lead zirconate titanate (PZT) particles by sol–gel method to tailor the dielectric parameters of PZT/poly(vinylidene fluoride) (PVDF) composites, aiming to generate morphology-controllable high ε′ and Eb but low-loss dielectrics. The effects of the Al2O3 shell with varying thickness and filler content on the dielectric characteristics of PZT/PVDF were examined systematically. The results indicate that the PZT@Al2O3/PVDF composites exhibit significantly enhanced Eb than the original PZT/PVDF, this enhancement is attributable to the moderate ε′ of the Al2O3 interlayer, which possesses high electrical resistivity. This interlayer not only mitigates local electric field distortion and concentration but also enhances the interfacial compatibility between the two components. Meanwhile, the PZT@Al2O3/PVDF composites also present significantly reduced dielectric loss and restrained conductivity owing to the insulating Al2O3 interlayer’s effective inhibition on the charge migration via inducing charge traps capturing mobile carriers and elevating the energy barrier for de-trapping. For instance, the PZT@Al2O3/PVDF (20 wt%) exhibits significant improvement in dielectric properties, demonstrating a high Eb of 9.8 kV/mm, a low tanδ of 0.018, and a large ε′ of 23.8 at 1000 Hz. Additionally, the utilization of Havriliak-Negami equation for theoretical fitting of experimental results further elucidates the Al2O3 shell’s effects on the polarization mechanism and suppression on charge migration. Furthermore, the overall dielectric performances of the composites can be effectively tuned by adjusting the interlayer’s thickness. Therefore, the prepared PZT@Al2O3/PVDF composites with large ε′ and high Eb coupled with low loss showcase promising applications in microelectronics and power systems.
Published Version
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