Sandwich structured BT-Fe₃O₄/PVDF composites with excellent dielectric properties and energy density

In this paper, BT-Fe₃O₄ hybrid particles were firstly fabricated using a chemical co-precipitation method, and then sandwich-structured BT-Fe₃O₄/PVDF composites (BT-Fe₃O₄/PVDF-S) were prepared. The influence of the BT-Fe₃O₄ and the sandwich structure on the dielectric properties of the composites was studied. The results showed that the BT-Fe₃O₄/PVDF-S composites exhibit enhanced dielectric performance. Interface activation E_a shows that conductive Fe₃O₄ nanoparticles can increase the number of activated electrons at the interface between the Fe₃O₄ and PVDF matrix, which can significantly enhance the interface polarization and dielectric response under an electric field. In addition, because the excellent insulating property of the PVDF layer can prevent the leakage of current through the sample and suppress the dipole polarization, the conductivity as well as the dielectric loss of the composites were also reduced. Moreover, the energy density of the 5 vol% BT-Fe₃O₄/PVDF-S composites is 2.24 J/cm³ at 2100 kV/cm, which is an enhancement of 1.77 times compared to the BT/PVDF (1.26 J/cm³ at 1800 kV/cm). The findings provide a simple but effective way for nanocomposites to have enhanced dielectric properties for use in next-generation electronics.