Electrocaloric response in a relaxor ferroelectric polymer at temperatures far below the dielectric maximum

Abstract

ABSTRACTRelaxor ferroelectric polymer poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) and its blends have been shown to exhibit a giant electrocaloric effect (ECE) over a broad temperature range, e.g. from 0 to 50 °C. Here, a special calorimeter was designed to directly characterize the heat absorbed QECE due to ECE cooling of the blend of P(VDF-TrFE-CFE) with P(VDF-TrFE) 65/35 mol% copolymer down to −15 °C, which covers the temperature range for many refrigeration applications. From QECE, the isothermal entropy change ΔS and adiabatic temperature change ΔT are deduced. The data reveal that at −15 °C the relaxor terpolymer/copolymer blend generates ΔS = 23.0J kg−1 K−1 and ΔT = 5.1K under 100 MV/m, which are still more than 65% of the ECE at room temperature. This temperature is far below the dielectric peak temperature of the relaxor blend and the results reveal the promise of the relaxor polymers for a broad range of EC cooling applications.