Evaluation of the polarization state of piezofiber composites

In this work, the polarization state of piezofiber composites consisting of lead zirconate titanate (PZT) fibers embedded in epoxy resin was evaluated by means of thermal wave methods. The average pyroelectric coefficient was found to be one order of magnitude less than that of PZT ceramic plates. The pyroelectric current spectrum was recorded during irradiating the composites with an intensity-modulated laser beam. We obtained a homogeneous polarization of the samples and were able to detect differences in the polarization magnitude. Additionally, the thermal conductance at the interface between PZT and epoxy resin was estimated. The thermal diffusivity of the material was determined by three different methods: (i) by means of the frequency dependence of the pyroelectric coefficient, (ii) by the laser flash analysis, and (iii) by calculation based on a parallel connection model. Its value yielded approximately 0.4 mm²/s.