Shear flexoelectric response along 3121 direction in polyvinylidene fluoride

Abstract

Flexoelectricity describes the strain gradient-induced electric polarization. Due to the restrictions of experiment technologies, some of the components of flexoelectric coefficient have not been experimentally obtained. In this letter, an experimental method for the measurement of the shear flexoelectric response along 3121 direction of polyvinylidene fluoride (PVDF) is presented. An experiment is conducted on various unpolarized specimens, where shear strain gradient is generated along the radial direction by applying torque to 3 specially designed specimens. The generated shear strain gradient is calculated via finite element analysis and the corresponding induced electrical response is measured. Dynamic torque is exerted on the specimens with a static bias value and at different frequencies. The shear flexoelectric coefficient μ3121 is found to have an average value of 1.037 × 10−8 C/m. With this method, the shear flexoelectric response along 3121 direction of PVDF is experimentally obtained. The experimental results show good agreement with the current research results and indicate the potential value of this material property for electromechanical device fabrication.

Flexoelectric materials and their related applications: A focused review

“…With the help of those direct and indirect measurements, a few polymers and dielectrics have been employed for studying their flexoelectric coefficients. As shown in Table 1, it is proved that the flexoelectric coefficients in normal dielectrics and polymers, represented by TiO 2 ceramic and the polyvinylidene fluoride (PVDF) [29][30][31][32][33][34], are in the range of 1-10 nC/m, which is in good accordance with the intrinsic flexoelectric values. But in some kinds of ferroelectric ceramics and single crystals, the results are quite different.…”

Flexoelectricity in dielectrics: Materials, structures and characterizations

“…This material has been the one that was measured for the components of its flexoelectric coefficient matrix, including 1211 ; 3121 ; 2312 and 1123 . [26][27][28][29] In addition to this shear component, the giant transverse and longitudinal flexoelectric coefficients in PVDF were observed. 15,[30][31][32] The difference apart from the flexoelectric characterization for solid material is that the residual piezoelectricity cannot be ignored for PVDF.…”

“…(C/m) 34.5, 37.331 À78.19, 1.6EÀ265,66 7.318EÀ426 1.037EÀ227 (9.2-9.6)EÀ3 29 S. Huang et al J. Adv. Dielect.…”

Fracture experiments and flexoelectric response of PVDF

“…Regarding the electrical properties of PVDF, we have the dielectric constant 26–32 in the range of 6 to 13 at ambient temperature. The flexoelectric coefficients 33 increase with the degree of crystallinity and vary in the range of 6 to 13 nC/m.…”