| Abstract: | Electroactive composites consisting of a ferroelectric ceramic in a polymer matrix have gained much interest as compliant electromechanical or pyroelectric sensors. Of the various theoretical models developed to understand the dielectric and electroactive properties of composites, the majority are based on a cube of unit dimensions representing the matrix with fractional inclusions representing the ceramic. Composite properties are dictated by the choice of constituent materials along with the intra- and inter-connectivity of the separate phases. A ceramic powder randomly dispersed in a polymer matrix is referred to as having 0-3 connectivity, i.e. the ceramic phase possesses no intra-connectivity throughout the composite in the x, y, and z directions, whereas the polymer possesses full intraconnectivity in these directions. For thin composite films, where the ceramic grain size is comparable to the film thickness, or for composites with high ceramic volume content, the degree of ceramic connectivity throughout the composite thickness will be enhanced over thick or low ceramic content composites, thus implying an amount of 1-3 connectivity within the composite. In order to investigate the properties of such composites, a cube model has been applied that deals with mixed 0-3 and 1-3 connectivity composites. This paper reports on the experimental and theoretical characterization of two different mixed connectivity composites, one with a polar polymer matrix and another with a nonpolar matrix. |
