Study on Dielectric Properties and Polarization Mechanism of MicG-KNN/PVDF Composites with in-Situ Grown Antiferroelectric Core-Shell Structure Fillers

This study utilized the in-situ growth technology of “high-temperature melting, water quenching, and controlled crystallization” to successfully fabricate stable core-shell structured anti-ferroelectric microcrystalline glass K_xNa_1-xNbO₃ (AFE MicG-KNN) powder fillers, which were subsequently combined with Polyvinylidene Fluoride (PVDF) polymer to further prepare MicG-KNN/PVDF composites. By precisely controlling the crystallization process, this method ensured a tight bond between the shell and the core, significantly enhancing the breakdown strength of the composites. Among them, the KNN-80/PVDF composite demonstrated the highest dielectric constant of 30 and the lowest dielectric loss, achieving an energy storage density of 6.6 J/cm³ under an electric field of 2400 kV/cm. Moreover, the technology allows for flexible adjustment of the core-shell ratio and shell thickness, providing an effective means for precisely regulating the dielectric properties of composites. This study delved into the dielectric properties and polarization mechanisms of MicG-KNN/PVDF composites, and proposes the “Shell Exchange Affects Dielectric Cluster region Mechanism (SE-DCRM)” to reveal its polarization mechanism. This research offers new perspectives for the development of high-performance polymer-based composites and deepens the understanding and optimization capabilities of the dielectric behavior of composites.