Low-temperature dielectric properties of Langmuir-Blodgett ferroelectric polymer films

Dielectric properties of the copolymer of vinylidene fluoride and trifluoroethylene films derived from the Langmuir-Blodgett technology have been investigated over the temperature range from 300 to 150 K at various frequencies. Below ∼240 K, peaks in the dielectric loss were observed to increase with increasing frequency. Nonlinear dielectric susceptibility and ferroelectric properties have been studied at different temperatures. The results show that the nonlinear dielectric susceptibility undergoes a remarkable change at ∼230 K. The results suggest a Β relaxation, which is related to the freezing of the molecular motions in the amorphous phase in the polymer films. The anomaly in the electrical properties at ∼230 K is due to the freezing of the molecular chains motions.