Synergistic enhancement of dielectric properties of polymer matrix composites by micro-nano bicomponent ceramics and conductive particles

Barium titanate (BaTiO₃, BT) was co-doped by solid-state sintering with niobium pentoxide (Nb₂O₅) and cobalt trioxide (Co₃O₄) as dopants. The modified barium titanate containing Nb and Co (BTNC) with larger particle size (0.5–1 μm) and silver powder (Ag) with smaller particle size (25 nm) were co-filled with polyvinylidene fluoride (PVDF) to prepare (BTNC-Ag)/PVDF three-phase composites. The morphology and crystal structure of composites were characterised by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. SEM shows that when the volume ratio of BTNC and Ag in the composite is 4:1, the two fillers have good dispersion in polymer matrix and could intersperse with each other to reduce voids. XRD patterns display that the filling of BTNC and Ag powders was conducive to promoting the enhancement of the diffraction peaks of β phase and γ phase in PVDF. The dielectric properties of the composites are effectively enhanced through the synergistic effect of the micro-nano bicomponent ceramic BTNC and conductive particles Ag co-filled polymer PVDF. When the volume ratio of filler (BTNC:Ag = 4:1) to matrix PVDF is 2/1, the dielectric properties of the composite are the best, the dielectric constant reaches 134.1 at 10² Hz and the dielectric loss is 0.04.