Ferroelectric Composites for Hydrophones

Considerations of the influence of crystal symmetry, macrosyrametry, and interphase connectivity have been used to explore possible macrostructures of interest as piezoelectric composites. Based on these design considerations, polymer-ceramic composites have been fabricated with 3-3 phase connectivity by the replication of natural template structures such as coral, or by a simplified fabrication technique of mixing volatilizable plastic spheres and PZT powders. 1-3 or 2-3 composites were made by perforated method. Polymer-Ceramic composites with 3-1 phase connectivity were made by embedding PZT rods or PZT spheres in various polymers. A modified connectivity model with 3-1-0 phase connectivity was introduced to improve the Poisson contraction problem found in 3-1 composites. In 3-1-0 composites voids were introduced into the polymer matrix to form a third phase which is isolated. All types of composites have been studied and it is shown that they have slightly lower permittivity, greatly improved dji and produce a much lighter material that can be adjusted to neutral buoyancy.