Importance of geometry and breakdown field on the piezoelectric d33 coefficient of corona charged ferroelectret sandwiches

Electrical and mechanical properties of corona poled three layer FEP/ePTFE/FEP sandwiches were studied theoretically and experimentally. Modeling of the properties has been performed, as well as their experimental verification. The piezoelectric d₃₃ coefficient has been studied with the objective of its possible optimization. It has been shown that the maximum value of the d₃₃ piezocoefficient depends on interrelation between solid and porous layers thicknesses, the intrinsic Young modulus of the porous layer and dependence of the breakdown field on the thickness of the porous layer. The best geometry of the sample can be designed considering the obtained results.