Advanced FeTiNbO6/poly(vinylidene fluoride) composites with a high dielectric permittivity near the percolation threshold

Abstract

FeTiNbO6 (denoted as FTN) is a recently discovered giant dielectric material with high Curie temperature (550 K). In this work, well dispersive FTN particles with mean particle size about 500 nm were synthesized by the improved solid-state reaction method. Using FTN particles as fillers and poly(vinylidene fluoride) (denoted as PVDF) polymer as matrix, multi-volume ratio (0%–60%) homogeneous ceramic/polymer composites have been prepared through a hot-pressing technology. At the same filling content, the FTN/PVDF composites display higher dielectric permittivity compared to the normal reported BaTiO3/PVDF composites, even larger than that of PVDF based composites using giant dielectric CaCu3Ti4O12 as filler. Especially, for 40 vol. % FTN/PVDF composites, the dielectric permittivity is as high as 181 measured at 100 Hz and 25 °C. Through the theoretical analysis correlated with structure evolution observation, it is deduced that the high dielectric performance originates from the combined effect of a variety of factors, such as giant dielectric semiconducting FTN particles, the micro-capacitor structure, and percolation phenomenon at appropriate volume fraction of FTN. Moreover, FTN/PVDF composites present strong dielectric relaxation behavior, which results from the superposition of the dielectric relaxation between PVDF and FTN. These flexible, easy processing FTN/PVDF composites with large dielectric permittivity values could find applications as new generational embedded capacitors.

Dielectric and energy harvesting properties of FeTiNbO6/PVDF composites with reinforced sandwich structure

“…As can be seen in Fig. a, FTN presents pure rutile phase with space group P4 2 /mnm , and no detectable impurity phase can be observed, confirming that the improved solid phase method is helpful to obtain a pure phase . Figure b gives the SEM image of FTN particles.…”

“…After that, the dielectric permittivity rises dramatically and at 50 vol% of FTN loading, it gets 610. However, it should be noted that the dielectric loss of the FTN/PVDF composites increase greatly with the increasing volume fraction of FTN filler because of the high conductivity of the FTN itself . As for the sandwich composites, the dielectric permittivity steadily increase, meanwhile the dielectric loss can be maintained at the low level comparing with the single layer FTN/PVDF composites.…”

“…As for the percolative composites, the conductive network formed by polar oxide with a giant dielectric permittivity near percolation threshold usually leads to high dielectric loss and electrical conductivity . Thus, the key issue lies in increasing dielectric permittivity, retaining low dielectric loss, and good insulation, while maintaining stable, controllable fabrication conditions and composite structure.…”

Core–shell structured Ag@C nanocables for flexible ferroelectric polymer nanodielectric materials with low percolation threshold and excellent dielectric properties

“…19,20 In recent years, the conductor-insulator core-shell structured nanoparticles have been used as ideal llers to fabricate percolative polymer nanocomposites with stable high dielectric constant and low dielectric loss. 14,[21][22][23][24] The conductor core is used to enhance the dielectric constant because of the interfacial polarization (namely, Maxwell-Wagner-Sillars effect), and the insulator shell serves as a dielectric interlayer to effectively reduce the dielectric loss through blocking the electron transfer between the adjacent conductor cores. 20,25,26 For instance, Dang et al integrated the Ag@TiO 2 core-shell nanoparticles into the PVDF, achieving a dielectric constant of approximately 32 at 100 Hz and a relatively low dielectric loss.…”

Greatly enhanced dielectric permittivity in La1.7Sr0.3NiO4/poly(vinylidene fluoride) nanocomposites that retained a low loss tangent

“…Most recently, incorporation of FeTiNbO 6 ceramic particles into PVDF was used successfully increase the 3 0 value of a composite with f ¼ 0.4 to z181 (at 100 Hz). 22 This was due to a very high 3 0 of z4 Â 10 3 of a FeTiNbO 6 ceramic, in which its high 3 0 originated from the intrinsic effect inside the grains (or particles). This opened a new way for using giant dielectric material as a ller to enhance 3 0 of a polymer matrix.…”