The research of effective flexoelectric coefficient along 1123 direction in polyvinylidene fluoride

Abstract

All dielectric materials exhibit flexoelectricity defined as a strain gradient-induced electric polarization. The flexoelectric coefficient measures electric polarization induced by strain gradient in dielectric materials. In this work, an approach to measure the 1123 component of the flexoelectric coefficient of polymeric materials is presented. Theoretical analysis and finite element analysis are performed on an un-polarized polyvinylidene fluoride rectangular beam. When deformation occurs in the specimen, a normal strain gradient is generated. The consistency of the elastic deformation determined through calculations and experimental measurements under applied loads was good. The experimental system was set up as follows: a circular sine wave load with bias value was applied to the specimen and the strain gradient-induced electric charge curve was measured. The flexoelectric coefficient μ1123 was obtained and was consistent with our theoretical calculations of the electric polarization induced by the strain gradients. This study provides experimental support for further theoretical investigations of flexoelectricity in polymers and may expand the range of applications of flexoelectric effects.

Asymptotic Homogenization Applied to Flexoelectric Rods

“…Recent papers have established detailed descriptions of their experiments to determine the flexoelectric properties of PVDF. More precisely, References [44] and [45] describe experiments to find the effective flexoelectric components μ1123 and μ2312 of the fourth order tensor μijkl for polyvinylidene fluoride. On account of the great difficulty in obtaining some experimental measurements, the relationship between the strain gradient and torque is deduced theoretically and further verified with finite element analysis.…”

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.…”

Ultrahigh flexoelectric effect of 3D interconnected porous polymers: modelling and verification

“…In the calculation, we assumed μ 1131 and μ 1133 are equal to each other, which can be concluded from the two coefficients given in the literatures such as Refs. 10,11 and 24 . The flexoelectric responses calculated using two theoretical models and also the experimental results under different frequencies and strains are shown in Fig.…”

“…Therefore, the flexoelectricity is expected to be more significant in nanomaterials compared with macroscopic materials since the strain gradient is inversely proportional to the structure size 6,7 . Significant flexoelectric effect has been observed in ferroelectrics 8,9 , polymers 10,11 , bone mineral 12,13 and semiconductors 14,15 .…”