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 a-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 202.3V was calculated from the flexoelectric coefficient mu(11) = 1.6 x 10(-8)C/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. (C) 2016 AIP Publishing LLC.