Decoupling method of flexoelectric coefficient tensor components in non-polarized polyvinylidene fluoride

Flexoelectricity, an electromechanical coupling effect between electric polarization and strain gradient, attracts growing attention for its increasing electro-mechanical efficiencies. Flexoelectric coefficient refers to the electromechanical coupling relationship of flexoelectricity, and was experimentally studied by employing different structures and approaches. Low symmetry materials such as polymers are potential candidates in applications of flexoelectricity for their excellent electromechanical properties. The key step is to experimentally solve the full flexoelectric coefficient tensor for those materials. Traditional methods such as cantilever bending, truncated pyramid compression can only directly measure a small part of flexoelectric coefficient tensor components. For those flexoelectric coefficients that cannot be measured directly, new experimental approaches are in great demanding. In this work, half cylinder and half-truncated cone models are employed, and the strain fields are analyzed. Torsional shear flexoelectric coefficients of non-polarized polyvinylidene fluoride (PVDF) have been obtained by newly designed decoupling method. With this method, shear flexoelectric coefficients μzρρφ and μzρzφ are decoupled. This approach has significant meaning in facilitating the completion of flexoelectric coefficient tensor in PVDF, and promotes the further study of flexoelectricity in low symmetry materials.