Performances of regular structure piezoelectrets made by template

Preparation of piezoelectret films with regular void structure by using a rigid template method is described in this paper. Laminated piezoelectret films with regular void structure are prepared by using porous polytetrafluoroethylene (PTFE) and fluoroethylenepropylene (FEP). The Young´s modulus of the laminated regular structure films is determined by dielectric resonance spectra. The quasi-static piezoelectric coefficient d₃₃ is measured by direct piezoelectric effect. The thermal stability of the piezoelectric d₃₃ coefficients is characterized by measuring the decay of d₃₃ at elevated temperatures. The charge dynamics in such regular structure piezoelectrets is investigated by analyzing the thermally stimulated discharge current spectrum in short circuit. The results indicate that the Young´s modulus of five-layer structure piezoelectret films is about 0.48 MPa. The quasi-static piezoelectric coefficient d₃₃ is not only up to 500 pC/N, but also shows good thermal stability. The de-trap charges mainly migrate along the surface of holes and ultimately recombinate with opposite charges which deposited on the same hole´s relative hole wall.