High dielectric constant and low dielectric loss poly(vinylidene fluoride) nanocomposites via a small loading of two-dimensional Bi2Te3@Al2O3 hexagonal nanoplates

Abstract

Two-dimensional (2D) core–shell structure Bi₂Te₃@Al₂O₃ nanoplates were synthesized from 2D Bi₂Te₃ nanoplates via a sol–gel method, where the 2D Bi₂Te₃ nanoplates were prepared via a microwave-assisted method. Homogeneous nanocomposite films, with poly(vinylidene fluoride) (PVDF) as the polymeric matrix and Bi₂Te₃ nanoplates or core–shell structured Bi₂Te₃@Al₂O₃ nanoplates as the fillers, have been prepared. The dielectric behavior of the Bi₂Te₃/PVDF and Bi₂Te₃@Al₂O₃/PVDF nanocomposites has been investigated. Compared with the Bi₂Te₃/PVDF nanocomposite, the Bi₂Te₃@Al₂O₃/PVDF composite film exhibits larger breakdown strength and lower dielectric loss, due to the highly insulating Al₂O₃ shell layer, as well as the Al₂O₃ dielectric constant being incorporated into the Bi₂Te₃ nanoplate surface. As a result, the composite film loaded with 10 vol% 2D Bi₂Te₃@Al₂O₃ nanoplates exhibits a high dielectric constant of 140 and a relatively low dielectric loss of 0.05 at 1 kHz. Furthermore, finite element simulations were carried out to understand the dielectric mechanism of Al₂O₃ shell layer effects on the dielectric performances of the nanocomposite films. This study provides a solution for obtaining high-k dielectric composites with low dielectric loss, which is highly desired for power systems and advanced electronics.