Study of ferroelectric polarization in poly(vinylidene fluoride) using the constant current method

Abstract

It is shown that the constant current method, in which a dielectric is charged with a constant current while the voltage is monitored, allows one to determine the dependence of the stable ferroelectric polarization with the electric field. The determination is based on two successive experiments separated in time by a short-circuit period: a charging process in which polarization switching occurs followed by a recharging with the same current polarity. Analysis of the recharging experiments for poly(vinylidene fluoride), PVDF, shows that the polarization appearing in it is a metastable ferroelectric polarization, due to the reorientation of ferroelectric polarization lost during the short-circuit period. The method was applied to measure the ferroelectric polarization in PVDF samples with different β-phase contents and in an exploratory way for a few other ferroelectric polymers.

Low-voltage operation of ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer capacitors and metal-ferroelectric-insulator-semiconductor diodes

“…8 The challenges to make ferroelectric nonvolatile memories with P͑VDF-TrFE͒ and related materials had begun in the 1990s, but most of the activities faced a significant problem in reducing the operating voltages. [9][10][11][12][13] In most cases, operating voltages were as large as 100 V or more. 14 Recently, Naber et al reported the promising result using thin P͑VDF-TrFE͒ ferroelectric films.…”

Electric measurements with constant current: A practical method for characterizing dielectric films

“…In Curve II ͓sample poled with the same current polarity as in Curve I but the current density is 2.5 mA/m 2 ͑I 0 ϭ20 nA͔͒, the potential grows more rapidly since switching does not occur, i.e., in this case, the incoming charge is not neutralized by the switching of the ferroelectric polarization. In our measurements, we took care to reduce the electric conduction in PVDF to a negligible value by performing the measurements in high vacuum, 20 i.e., J C (t)ϭ0 in Eq. ͑3͒.…”

“…14 It was also shown that the CC method was suitable for determining the dependence of the stable ferroelectric polarization on the electric field in PVDF samples. 20 To do it, successive charging experiments were performed with the same polarity. Experimental procedures and results are discussed in detail in Ref.…”

Ferroelectric Switching and Dielectric Response of P(VDF-TrFE)/PMMA Blends

“…Polarization switching characteristics were determined at room temperature by using a linear-voltage increasing apparatus [8]. The electric field variation was typically 0.66…”

“…The results presented here correspond to the third or higher reversal polarization runs, after stabilizing the response of the system (the data become reproducible after a few cycles). The non-ferroelectric component of the electrical polarization and the electrical conduction contribution were eliminated by taken successive polarization cycles, as described in [8]. Thermal analysis was performed by differential scanning calorimetry (DSC) in a Mettler TAIO-DSC30 apparatus, from 230 K to 470 K, with linear heating/cooling rates of 10 K/min, in controlled atmosphere.…”