Electrocaloric effect in γ-irradiated P(VDF-TrFE) relaxors

Relaxor features were induced in an equimolar P(VDF-TrFE) copolymer by high doses of γ-rays. The electrocaloric responses of the samples were investigated, before and after irradiation. For the virgin copolymer, the maxima isothermal entropy change (ΔS ≈ 22.5 J/kgK) and adiabatic temperature change (ΔT ≈ 6 K) of conformational origin were observed at 90 °C and above, for a 120 MV/m applied electric field. For the γ-irradiated sample, we observed the lowering of the working temperature range by circa 15 °C, but higher external electric fields of 160 MV/m were required to recover the large level of electrocaloric response in these polymeric relaxors. The refrigerant capacity of the materials, virgin or relaxors, was evaluated as 130 J/kg, showing their high potential for applications as electrocaloric refrigerators.