Suppressing loss tangent with significantly enhanced dielectric permittivity of poly(vinylidene fluoride) by filling with Au-Na1/2Y1/2Cu3Ti4O12 hybrid particles

Three-phase gold nanoparticle-Na1/2Y1/2Cu3Ti4O12 (Au-NYCTO)/poly(vinylidene fluoride) (PVDF) composites with 0.095-0.487 hybrid particle volume fractions (f) were fabricated. Au nanoparticles with a diameter of similar to 10 nm were decorated on the surfaces of high-permittivity NYCTO particles using a modified Turkevich's method. The polar beta-PVDF phase was confirmed to exist in the composites. Significantly enhanced dielectric permittivity of similar to 98 (at 1 kHz) was obtained in the Au-NYCTO/PVDF composite with f(Au-NYCTO) = 0.487, while the loss tangent was suppressed to 0.09. Abrupt changes in the dielectric and electrical properties, which signified percolation behavior, were not observed even when f(Au-NYCTO) = 0.487. Using the effective medium percolation theory model, the percolation threshold (f(c)) was predicted to be at f(Au-NYCTO) = 0.69, at which f(Au) was estimated to similar to 0.19 and close to the theoretical f(c) value for the conductor-insulator composites (f(c) = 0.16). A largely enhanced dielectric response in the Au-NYCTO/PVDF composites was contributed by the interfacial polarization effect and a high permittivity of the NYCTO ceramic filler. Au nanoparticles can produce the local electric field in the composites, making the dipole moments in the beta-PVDF phase and NYCTO particles align with the direction of the electric field.