Giant electrocaloric effect in ferroelectric poly(vinylidenefluoride-trifluoroethylene) copolymers near a first-order ferroelectric transition

We present directly measured electrocaloric effect (ECE) from the poly(vinylidenefluoride-trifluoroethylene) 65/35 mol. % copolymer. The data reveal a large difference in the ECE between that measured in applying and in removing the electric field. The difference is significantly reduced by modifying the copolymer with 20 Mrad of high energy electron irradiation. Moreover, an isothermal entropy change Delta S-int = 160 J kg(-1) K-1 and an adiabatic temperature change Delta T-int = 35 degrees C can be induced in the irradiated copolymer. These results demonstrate the promise of achieving a significant ECE in ferroelectric polymers near first-order ferroelectric-paraelectric transition where multiple intermediate phases can exist. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4756697]