Dielectric properties of three ceramic/epoxy composites

Three ceramic/epoxy composites were under investigation. The ceramic fillers include self-synthesized BaTiO3 and commercial BaTiO3 and Pb(Mg1/3Nb2/3)O3. Effects of the filler ratio and testing temperature and frequency on the dielectric properties of these three composites were discussed. The self-synthesized BaTiO3/epoxy composite had the best dielectric property. Its 40%-filler composite had a dielectric constant of 44, which was higher than those of 27 and 24 for the commercial BaTiO3 and Pb(Mg1/3Nb2/3)O3 composites, respectively. The large ceramic aggregates formed in epoxy are the reason for the self-synthesized BaTiO3/epoxy composite having a higher dielectric constant of 44. Composite dielectric constant was proportional to the volume ratio of the ceramic filler and remained constant at different test temperatures and frequencies. For the BaTiO3/epoxy composites, the fabrication process of slurry-casting or screen-printing can have an effect on their porosity. The composites with a low porosity lead to a low dielectric loss tangent.