Polytetrafluorethylene-based high-k composites with low dielectric loss filled with priderite (K1.46Ti7.2Fe0.8O16)

Composite materials with a high permittivity (high-k) and low dielectric loss represent an important research direction for the rapid development of modern electronic. This article is about high-k composite with low dielectric loss (dielectric constant is approximately 11, and dielectric loss is only 0.02 at 1 MHz and about 50 wt % of filler) based on a polytetrafluorethylene (PTFE) compounded with priderite (K_1.46Ti_7.2Fe_0.8O₁₆). The dielectric permittivity about ε' ≈ 10³ and the dielectric loss of tgδ ≈ 2 have been found for filler content about 50 wt % (30 vol %) and, respectively, ε' ≈ 11 and tgδ ≈ 0.02 for 1 MHz. To produce filler, amorphous potassium polytitanate was synthesized by molten salt method, modified in aqueous solution of iron sulfate, crystallized at 700 °C and further treated in the aqueous dispersion of PTFE. The obtained product was pressured, dried and investigated by X-ray diffraction and scanning electron microscopy. Dielectric properties of the composite with different ceramic filler content (1–90 wt %) were studied using impedance spectroscopy in the frequency range of 10⁻² to 10⁶ Hz. The influence of frequency on electric conductivity, permittivity, and dielectric losses was analyzed taking into account the experimental data on porosity, apparent density obtained for the composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48762.