Microwave properties of ferroelectric ceramic/polymer 0-3 composites

A series of polymers, and composites, consisting of Pb(Mg_1/3 Nb_2/3)O₃(PMN), 0.67 Pb(Mg_1/3Nb _2/3)O₃-0.33, PbTiO₃ (PMNT), or Fe₃ O₄ particles and epoxy, were evaluated for dielectric constant and loss, as well as reflectance, transmittance, and absorbance. The composites´ loadings were varied and properties measured in the X-band frequencies. The ferromagnetic Fe₃O ₄ material was chosen for the sake of comparison, being commonly used for absorbance in composites. The powder loading in the composites was varied between 0 and 45 vol.%. The scattering parameters S11* (reflectance) and S21* (transmittance) were obtained directly from an HP8510 two-port network analyzer. Absorbance and complex dielectric permittivities were then obtained at 10 GHz for the epoxy composites at 25-vol.% loading. The magnitudes of the reflectance were similar, but transmittance (S21) was lower for the Fe₃O₄ epoxy composite due to higher absorbance. From the data, ferroelectric epoxy composites had excellent absorbances and microwave properties, and were comparable to Fe₃ O₄ composites