Dielectric and energy harvesting properties of FeTiNbO6/PVDF composites with reinforced sandwich structure

Flexible dielectrics have been the major enabler for a number of applications in advanced electronic and electrical power systems. As an important flexible dielectric material, polymer composites are promising in raising the poor dielectric properties of neat polymer of current use. In this study, a class of topological-structure modulated multilayer composites comprising a percolation layer (FeTiNbO6[FTN]/polyvinylidenefluoride [PVDF]) intercalated between two insulating layers (PVDF or BaTiO3[BT]/PVDF) are assembled into sandwich structures by a facile hot-pressing method. For the prepared sandwich structure, FTN/PVDF film acts as a semiconductive layer to raise dielectric permittivity, while two insulating layers at top and bottom of composite are used to suppress conductivity and dielectric loss. Resulted from the unique performances of the FTN/PVDF film and strong interfacial polarization, the sandwich composite possesses improved dielectric and insulation properties. Moreover, compared with FTN/PVDF, the BT20-FTN40-BT20 has lower dielectric loss and higher insulation properties, and after poling at 20 kV/mm for 6 h, it exhibits excellent vibration energy harvesting properties in cantilever mode. Thus, a piezoelectric energy harvester constructed from this sandwich composite can be used for self-driving wireless sensors. POLYM. COMPOS., 40:E570-E578, 2019. (c) 2018 Society of Plastics Engineers