POLING OF P(VDF-TrFE) WITH FERROELECTRICALLY APPLIED DIELECTRIC DISPLACEMENT

A new poling technique is presented, in which an unmetallized polymer film is poled in a sandwich between ferroelectric crystals. If a high electrical voltage is applied to the stack, the polarization of the ferroelectric crystals is saturated, and the interfaces to the polymer film form well defined sources for a high dielectric displacement. Destructive electrical breakdown is prevented. Therefore ferroelectric electrode poling (FEP) is in particular useful if poling fields near the breakdown field are required or even if the film contains imperfections. P(VDF-TrFE) films in the composition 70/90 mol-% have been poled between TGS and BaTiO3 crystals. The polarization obtained shows a uniform profile over the film thickness. Poled between BaTiO3, a hie, h polarization and a high pyroelectric coefficient are achieved. These results show that charge injection from metal electrodes is not essential for the poling of P(VDF-TrFE) with a high dielectric displacement.