Electrocaloric effect of the relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer

We investigate the temperature dependence of the electrocaloric effect in a relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer and show that the isothermal entropy change Delta S is proportional to the square of the electric displacement D (Delta S=-1/2 beta Delta D-2) and the coefficient beta increases with temperature. This temperature dependent behavior of beta is caused by the ferroelectric relaxor nature of the polymer in which the polarization response from the nanopolar regions does not generate much entropy change. Consequently, the electrocaloric effect in the relaxor ferroelectric terpolymer is smaller than that in the normal ferroelectric copolymer.