Electroactive and dielectric properties of corona and thermally poled polymer-ceramic composites

Composites of ferroelectric ceramic inclusions in the matrix of the polymer show piezoelectricity and pyroelectricity if they are suitably poled (either thermally or by corona charging). Such composites are important because they may be regarded as a model system in which the electroactive crystalline phases of the ceramics are dispersed in an amorphous phase of the polymer. The electroactive properties of such a two-phase system are a function of the dielectric and the elastic contents of both phases. Polymer/ceramic composite films have been produced by introducing fine grain (1 μm) PZT powder in the matrix of PVDF (polyvinylidene fluoride) using a hot rolling mill followed by high-pressure casting. These films were poled both by the conventional (thermal) technique and by corona charging. The results of measurements of the dynamic pyroelectric coefficient and the dielectric properties are given