Barium titanate coated and thermally reduced graphene oxide towards high dielectric constant and low loss of polymeric composites

Novel barium titanate (BT) layer coated and thermally reduced graphene oxide (TGO) hybrid sheets (BT@TGO) were successfully synthesized by a facile sol-gel method combining with thermal treatment process (600 °C) under nitrogen atmosphere. The BT precursors attached on graphene oxide (GO) sheets were crystallized into perovskite structure with high permittivity and GO sheets were thermally reduced heavily at such high temperature simultaneously. The hybrids were used as filler to fabricate high performance dielectric polyvinylidene fluoride (PVDF) composites by solution blending method and their dielectric performances were studied. It was found that addition of BT@TGO decreases the electrical conductivity when compared with TGO/PVDF composites and pure PVDF, and BT@TGO/PVDF composites exhibit not only high dielectric constant but also low dielectric loss. For instance, at 10³ Hz, the dielectric constant of PVDF composites containing 8.0 wt% BT@TGO is up to ∼56.3 at room temperature, which is over 5 times than that of pure PVDF polymer (∼10.3). More importantly, the dielectric loss is suppressed and only 0.058, which should be attributed to the effective encapsulation of insulating BT layer with high permittivity on the TGO surface. In addition, the improved thermal stability and crystallization behavior of BT@TGO/PVDF composites were also investigated.