Dielectric properties of PZT–epoxy composite thick films

Composites with 0–3 connectivity patterns were prepared by gravity casting by using different amounts of Pb(Zr,Ti)O3 powder with concentrations (x = 0%, 2.5%, 5%, 7.5%, 10% and 15%) embedded into a polymer matrix of epoxy resin. The role of the filling factor and of the gradient composition on the effective dielectric properties was theoretically investigated by Finite Element Method. The frequency dependencies of the real and imaginary parts of the dielectric permittivity at various temperatures showed a few relaxation mechanisms that were discussed. The composites exhibit a permittivity gradient and act as a natural impedance match system in the frequency range of 2–6 GHz, resulting in very low reflections. The compositionally graded PZT–epoxy resin composite thick films are suitable as adapting impedance materials for microwave applications.