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

Abstract

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 ΔS is proportional to the square of the electric displacement D (ΔS=−1/2βΔD2) and the coefficient β increases with temperature. This temperature dependent behavior of β 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.