Flexible BaTiO3/SiC@PbTiO3/epoxy composite films with enhanced dielectric performance at high frequency

Flexible polymer composites with high dielectric constants and low dielectric losses at high frequencies are highly desired in microwave and RF applications. However, a high dielectric constant is often obtained at the expense of flexibility because a high loading of filler is needed. In this work, we synthesize a core-shell structured 1D filler by coating high-dielectric-constant PbTiO3 onto the surface of low-thermal-expansion-coefficient SiC nanofibers, which are then incorporated into the epoxy matrix together with BaTiO3 nanoparticles to form the multi-phase BaTiO3/SiC@PbTiO3/epoxy composite film. A high dielectric constant (35 at 100 Hz and 20 at 5 GHz) and a low dielectric loss (0.023 at 100 Hz and 0.13 at 5 GHz) are achieved as the filling content of SiC@PbTiO3 and BaTiO3 is 5.24 wt% and 80 wt%, respectively. Prediction models of the effective dielectric constant of polymer-based composites reveal that a continuous polarization network is constructed in the composites owing to the physical contact between BaTiO3 and PbTiO3. The construction of the multi-phase filler provides a feasible way to effectively adjust and improve the dielectric properties of polymer-based composite films.

Automated summary

This work synthesizes a core-shell structured 1D filler by coating high-dielectric-constant PbTiO3 onto the surface of low-thermal-expansion-coefficient SiC nanofibers, which are then incorporated into the epoxy matrix together with BaTiO3 nanoparticles to form the multi-phase BaTiO3/SiC@PbTiO3/epoxy composite film. The composite material exhibits high dielectric constant and low dielectric loss.