Effect of TiO_2 on enhanced pyroelectric activity of PVDF composite

摘要

Thin films of a ferroelectric polymer matrix made of poly(vinylidene fluoride) (PVDF) incorporated with a non-ferroelectric inclusion, TiO_2, were prepared with different volume fractions (0-30 wt%). The dielectric and pyroelectric properties of the PVDF/TiO_2 composite thin films are revealed as a function of different annealing temperatures (60 to 140 °C). Theoretical models, including Maxwell, Clausius-Mossotti, Furukawa and effective medium theory models were employed to describe the effective dielectric permittivity of the composites. This report also studies the effect of a non-ferroelectric inclusion, which contributed to the enhancement of pyroelectric activity after the poling process, in a ferroelectric polymer matrix based composite. An increase in the dc conductivity of the polymer matrix led to an easier poling process and reduced the required poling electric field from 260 to 120 MV m~(-1). The pyroelectric coefficient of the polymer composite has been enhanced at a much lower poling electric field. The surface and structural properties of the thin film composites were also characterized by scanning electron micrographs, Fourier transform infrared spectroscopy and χ_ray diffractometry.