Preparation and characterization of PbTiO3–epoxy resin compositionally graded thick films

The preparation and properties of compositionally graded PbTiO3 (PT)–epoxy resin (EPR) composite thick films are reported in this study. Various graded specimens were prepared using gravity casting method by embedding PT powders into the EPR matrix. The existence of a graded structure with two distinct phases, a good intermixing, some air pores, and different morphologies, was confirmed by scanning electron microscopy micrographs. The dielectric constants of these composites have values in the range 5–12 at the frequency of ∼104 Hz and about 3–13 at ∼5 × 108 Hz. The composites with permittivity gradient act as a natural impedance match system in the frequency range 2–4 GHz, resulting in very low reflections. Therefore, the compositionally graded PT–EPR composite thick films are suitable as adapting impedance materials for microwave applications.