Large electrocaloric effect in lead-free K0.5Na0.5NbO3-SrTiO3 ceramics

The electrocaloric effect (ECE), i.e., the adiabatic temperature change DTEC, of the lead-free relaxor ferroelectric 0.85K(0.5)Na(0.5)NbO(3)-0.15SrTiO(3) (KNN-STO) ceramics is investigated. The ECE data obtained by a direct method show the existence of a large ECE near the temperature of the dielectric permittivity maximum. Due to the high break-down electric field, a large DTEC exceeding 1.2K at 300K and 1.9K at 340K was observed at 159 kV/cm in a broad temperature range of 80 K. Such a high ECE response near the room temperature is comparable to that found in lead-based ceramic materials, thus making KNN-STO a strong candidate to replace lead-based materials in future electrocaloric applications. (C) 2015 AIP Publishing LLC.