Nanocomposites with BaTiO3–SrTiO3 hybrid fillers exhibiting enhanced dielectric behaviours and energy-storage densities

Abstract

Herein, small loadings of SrTiO₃ nanowires (ST NWs) were synthesized and grafted onto the surface of BaTiO₃ nanoparticles (BT NPs) in a hydrothermal process. Nanocomposites comprised of P(VDF-HFP) matrix and ceramic fillers were prepared using BT–ST nanocrystals of different molar ratios. Microstructure and thermal analysis confirm that BT NPs have been successfully functionalized with polyphenol-Sr²⁺ shells on the surface, and the BT–ST-P(VDF-HFP) nanocomposites can obtain a higher thermal stability than both pure P(VDF-HFP) and BT-P(VDF-HFP) composites. Dielectric properties measured at various frequencies and temperatures indicate that the nanocomposites with several BT–ST ratios exhibit enhanced dielectric properties over a wide frequency range. With a BT–ST molar ratio of 2 and the dielectric constant of 7.5 vol% sample can increase by 3.2 and dielectric loss can decrease by 0.015, compared with BT-P(VDF-HFP) nanocomposites. In addition to the dielectric behaviours progress, the BT–ST-P(VDF-HFP) composites also possess higher electrical displacements and corresponding energy-storage densities compared to BT-P(VDF-HFP) nanocomposites. The energy density of the optimal BT–ST-P(VDF-HFP) sample is four times higher than that of pure P(VDF-HFP) under an electric field of 20 kV mm⁻¹. All the improved performances suggest an easy method to fabricate nanocomposites bearing potential electrical applications.