Characterization and performance of plate-like Ba_0.6Sr_0.4TiO₃/Poly(vinylidene fluoride – trifluoroethylene -chlorotrifluoroethylene) composites with high permittivity and low loss

Plate-like Ba_0.6Sr_0.4TiO₃/Poly (vinylidene fluoride - trifluoroethylene -chlorotrifluoroethylene) (P-BST)/P(VDF-TrFE-CTFE) functional composite films were prepared via a tape casting method. All samples have textured microstructure, and the orientation degree of the composites is above 50%. Though pure terpolymer has a low dielectric permittivity (20.4) and a high loss (0.52), the introduction of ceramic particles can effectively enhance its permittivity as well as decrease the loss. The composite filled with 40 vol% ceramic fillers showed a high permittivity of 88.3 as well as a low loss of 0.056 accompanying with a high dielectric tunability about 30%. Additionally, the dielectric tunable theoretical model of the composite was investigated. The functional relationship between phenomenological coefficient ratio β₁/β₂ and the ceramic content was obtained. The final results indicate that the value of β₁/β₂ is inversely proportional to the ceramic phase content, as opposed to the composites matrix's dielectric constant which cannot be tuned by the electric field.