Correlation between molecular dynamics and thermal hysteresis in the 60/40 vinylidene fluoride and trifluoroethylene ferroelectric copolymer

Thermal hysteresis associated with ferroelectric to paraelectric phase transition is investigated in a ferroelectric copolymer of vinylidene fluoride and trifluoroethylene, using X-ray diffraction and incoherent neutron scattering. The lattice spacing derived from the diffractograms, shows hysteresis at the ferro–paraelectric phase transition. The analysis of the elastic incoherent neutron spectra indicates that besides the structural component, the thermal hysteresis phenomena appears in the dynamics of the copolymer. Furthermore, the area of the hysteresis loop increases with Q until it reaches the Q value corresponding to the Braggs peak. At a given temperature, inside the ferroelectric hysteresis loop, the incoherent quasielastic component differs in intensity depending on recording the spectrum at the heating or at the cooling scan.