Dielectric properties of polymer mixtures with CaTiO3 perovskite: conventional and plasma-treated ceramic powders

We studied dielectric properties of a composite consisting of organic matrix and ceramic filler based on a high-permittivity CaTiO₃. This very stable ceramic dielectric material was added into Dentacryl polymer in various proportions up to 32 vol.%. Besides crushed powder, a plasma-treated powder of a hollow character was applied. The ceramics contributed to a markedly enhanced permittivity of the composite, whereas the losses remained rather low and the DC resistivity high (ε_r = 30, tan δ = 0.05, ρ_v = 10¹³ Ωm). The system followed the mathematical model – the mixing rules concerning the frequency-dependent response to the electric field, whereas rather low concentrations of the CaTiO₃ admixture were high enough to increase the dielectric characteristics over the mean values predicted by the mixing rules. This behaviour was typical mainly for the hollow powder, which enhanced the dielectric performance stronger than the ordinary form of CaTiO₃ powder. However, because of less lossy character, the crushed powder of a traditional technology origin is more universal for making dielectric composites.