Synthesis, characterization and dielectric properties of surface functionalized ferroelectric ceramic/epoxy resin composites with high dielectric permittivity

The thermosetting polymer-ceramic composites were prepared via solution mixing method with epoxy resin as the matrix and Ca and Zr doped BaTiO3 ceramics as the filler. Dopamine was employed to modify the surface combination between ceramic particles and polymer matrix. The effects of filler on the microstructure, morphology, and dielectric properties of ceramic-polymer composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscope, field emission scanning electron microscope, and the precision impedance analyzer. TEM results showed that the thickness of dopamine coated on the surface of ceramic particles was about 15 nm. SEM results showed that the filler was incorporated in the matrix homogeneously. The dielectric constant and loss tangent of composites decreased with the frequency increasing, while the dielectric constant increased with the addition of ceramic filler. When the filler content was 25 vol%, the dielectric constant of composites was 51 which was eight times more than that of pure epoxy resin. Theoretical models were employed to predict the effective dielectric permittivity of composites and were compared with the experimental data.