Bi2S3/poly(vinylidene fluoride) composite with high dielectric constant and unusual low dielectric loss based on preferentially oriented fillers

The main challenge in the field of capacitors is how to reconcile the contradiction of lowering the dielectric loss while maintaining a high dielectric constant of polymer based composites. In this work, a novel two-phase ferroelectric polymer composite, consisting of semiconducting bismuth sulfide (Bi2S3) nanorods and a poly(vinylidene fluoride) (PVDF) matrix, was fabricated by a sequence of casting, hot-stretching and hot-pressing techniques. Orderly polymer composites based on PVDF assembled with parallel aligned Bi2S3 nanorods were realized in the composites after a hot-stretching-pressing process. It's interesting to note that those orderly polymer composites exhibit excellent dielectric properties. Results show that the composites with oriented structure have high dielectric constant and unusual low dielectric loss. The parallel aligned Bi2S3 nanorods along the tensile-strain direction could be responsible for the improvement of dielectric properties of the composites. This study also provides an extremely useful method to reduce the dielectric loss of similar kinds of composites.