Ferroelectric to paraelectric phase transition mechanism in poled PVDF-TrFE copolymer films

Direct experimental insights into the structural and dynamical mechanisms for ferroelectric beta to paraelectric alpha phase transition in a poled PVDF-TrFE copolymer is obtained from in situ x-ray diffraction and quasielastic neutron scattering measurements at high temperatures. It is observed that the beta-to-alpha phase transition proceeds through two energetically distinct processes, which are identified here as the nucleation and growth of an intermediate gamma phase with random skew linkages followed by a gamma-to-alpha transition. The two energetically distinct microscopic processes can explain the stages of evolution for beta-to-alpha phase transition observed from heat flow measurements.