Microscopic origin of the morphotropic-like phase boundary in P(VDF-TrFE)

Ferroelectric materials with compositions near a morphotropic phase boundary (MPB) exhibit dramatically enhanced electromechanical properties, which could be utilized in advanced actuators, transducers, sensors and energy-harvesting applications. We have recently observed [1] a morphotropic-like phase boundary for the first time in an organic material, poly(vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)], which makes it possible to develop high-performance electroactive polymers. This talk describes the results of our extensive first-principles calculations for this class of polymers. We find that chirality introduced by the TrFE monomers plays the central part in the structural competition that leads to a phase boundary between the trans-planar and the 3/1-helical chain conformations, explaining and supporting the experimental results.
Y. Liu, H. Aziguli, B. Zhang, W. Xu, W. Lu, J. Bernholc, Q. Wang, Nature 562, 96 (2018).