Novel piezoelectric ceramic/polymer composite transducers

The design, processing conditions and electromechanical characterization of novel piezoelectric ceramic/polymer composites with 2-2 and 3-3 connectivity is presented. The ceramic structures made of PZT were prepared by Layered Manufacturing, namely by Fused Deposition of Ceramics (FDC) process. The ceramic phase in the form of fibers or sheets was oriented at different orientation angles θ with respect to the x₃ axis of the sample, which varied between 0° and 75°, in 15° increments. The sintered structures were placed in Spurr Epoxy polymer and diced in 2mm thickness. The electromechanical and elastic properties were investigated as a function of orientation angle θ. The longitudinal piezoelectric charge coefficient showed a decrease in the property as the θ increases. It was found that as the orientation angle θ was increased, the transverse piezoelectric charge coefficient d_3l changed its sign from a negative to a positive value at θ = 37.5° reaching a maximum value at 45° for both types of composites. Due to the contribution of a positive d_3l coefficient, a significant increase in the hydrostatic charge coefficient was observed.