Fig. 2: Ferroelectric characteristics of P(VDF-TrFE).

a Electric displacement D as a function of the applied electric field E, resulting in ferroelectric D–E hysteresis loops. b Macroscopic strain S as a function of the field E yields the typically shaped butterfly curve. Both D–E and S–E were measured in the ferroelectric state at 300 K. Here, the capacitor was driven with a 10 Hz triangular waveform. c Specular XRD measurements, showing the lattice spacing d as a function of temperature (crystalline phase transition). d Remnant polarisation Pr as a function of temperature. The solid line through the measured values is a guide for the eye.