Microwave dielectric properties of PTFE/CaTiO3 polymer ceramic composites

Abstract: CaTiO3 ceramic powder filled polytetrafluoroethylene (PTFE) composites with various filler volume fractions up to 60vol.% were prepared. The effects of volume fraction of the ceramic filler on the microstructure and microwave dielectric properties of the composites were investigated in detail. As the volume fraction of the ceramic filler increases, the dielectric constant (ɛ r) and the temperature coefficient of resonant frequency (τ f) of composites increase, while the product of quality factor and frequency (Q × f) decreases. Composites with 40vol.% CaTiO3 exhibited good microwave dielectric properties: ɛ r =13 at ∼5GHz, Q × f =930GHz, and τ f =260ppm/°C. Different mixing rules were used to predict the dielectric constant of composites, and it was found that the dielectric constants predicted by Effective Medium Theory (EMT) were in good agreement with experimental data. [Copyright &y& Elsevier]