A Large Piezoelectric Anisotropy of a Three-Component Composite with Variable Connectivity

Proposed are two types of three-component piezoelectric composites that change connectivity from 2-2 to 1-3 and contain polarized ferroelectric ceramic and polymer components, i.e., layer 1 reinforced by rods–layer 2–layer 1 reinforced by rods– . . . (type 1) and laminated rods (layer 1–layer 2–layer 1– . . . ) embedded in a matrix (type 2). Some cases of the large anisotropy of piezoelectric coefficients d₃₃^*/d₃₁^* and e₃₃^*/e₃₁^* are analyzed for the composites of the type 1. Original cases of simultaneous reaching d₃₃^*/d₃₁^* 0 and e₃₃^*/e₃₁^* > 10 as well as e₃₃^*/e₃₁^* and d₃₃^*/d₃₁^* at different volume concentrations of the components in the composites of the type 2 are also considered. It is shown that these ratios essentially depend on electromechanical constants of the components, their volume concentrations, microgeometry, as well as on jumps of these constants and internal fields at boundaries between the components.