Connectivity and piezoelectric-pyroelectric composites

Connectivity is a critical parameter in composites designed for use as piezoelectric transducers or as pyroelectric detectors. There are ten important connectivity patterns in diphasic solids, ranging from a 0-0 unconnected checkerboard pattern to a 3-3 pattern in which both phases are three dimensionally self-connected. Processing methods for manufacturing some of these patterns are described. Series and parallel models for composite piezoelectrics and pyroelectrics lead to several interesting results, such as a diphasic pyroelectric in which neither phase is pyroelectric. The models are also helpful in interpreting the structure-property relations in single-phase materials where the crystal structures mimic certain connectivity patterns.