Significantly enhanced dielectric permittivity and low loss in epoxy composites incorporating 3d W-WO3/BaTiO3 foams

With the rapid development of miniaturization and high integration of electronic devices, increasing attention has been paid to the exploration of dielectric composites with further improved dielectric permittivities. Herein, a unique design of high dielectric permittivity composites consisting of three-dimensional porous W-WO3/BaTiO3 foams hosted in epoxy matrix is proposed. It is demonstrated that the introduction of W-WO3/BaTiO3 foams into the epoxy matrix results in substantially improved dielectric permittivities in comparison with the epoxy matrix. Meanwhile, low loss which is comparable to that of the epoxy matrix is well maintained. Interestingly, obviously enhanced dielectric permittivities and greatly depressed loss are concurrently achieved via increasing the oxidation temperature. In particular, the composite with 53.1 wt% W-WO3/BaTiO3 foam oxidized at 1300 °C exhibits a high dielectric permittivity of ~ 536 and a low loss tangent of ~ 0.05@10 kHz which are about 149 and 1.5 times those of the epoxy matrix, respectively. It is believed that the strong interfacial polarization and the numerous equivalent micro-capacitors result in the significantly improved dielectric permittivities. The finite element simulation results reveal that the formation of the WO3 shell on the surface of W can effectively weaken the leakage current density, yielding the sharply depressed loss. This work provides a new strategy to design polymer composites with simultaneous high dielectric permittivity and low loss, and the strategy could also be applicable to the exploration of other high-performance dielectric composites.