Improved approach to measure the direct flexoelectric coefficient of bulk polyvinylidene fluoride

We experimentally studied the built-in polarization induced effective piezoelectric constant and direct flexoelectric coefficient in α-phase bulk polyvinylidene fluoride (PVDF). This phenomenon was detected and discussed based on the compression of a truncated cone. An improved mechanical formulation of flexoelectricity was presented and discussed in this study, and the experiment was carried out based on the charge measurement. From the experiment study, a flexoelectric coupling coefficient 202.3 V was calculated from the flexoelectric coefficient μ11=1.6×10−8C/m for bulk polyvinylidene fluoride. We measured the flexoelectric response of bulk PVDF with consideration of the residual piezoelectric contributions and geometry-dependent calibration, which affect the flexoelectric measurement.