Dynamic shear piezoelectricity of poly(vinylidene fluoride) thin films

The shear wave properties of stretched and polarized PVDF thin films have been studied under application of a high frequency electric field parallel to the film surface. It has been found that the piezoelectric constants d/sub 15/ and d/sub 24/ do not act effectively under conditions of thickness resonance, in contrast with their large static values. This result is in severe disagreement with the symmetry predictions and raises the necessity for thorough investigation of the contribution of the amorphous phase as well as the collective behaviour of piezoelectric crystallites.