Large electrocaloric effect in La-doped 0.88Pb(Mg1/3Nb2/3)O3-0.12PbTiO3 relaxor ferroelectric ceramics

The temperature and electric field dependences of electrocaloric effect (ECE) of 0.5 mol.% La-doped 0.88Pb(Mg1/3Nb2/3)O-3-0.12PbTiO(3) (La-doped 0.88PMN-0.12PT) relaxor ferroelectric ceramic were investigated by direct measurement method using a home-made adiabatic calorimeter. Direct and indirect ECE were compared and large discrepancy was observed not only in a magnitude but also in the changing trend. Dualepeak effect was observed in the Delta T-ECE -T curves, which can be ascribed to the evolution of polar nanoregions (PNRs). The first ECE peak appears near the depolarization temperature (T-d) of 40 degrees C at low electric field, and the second ECE maxima with Delta T-ECE of 0.44 degrees C at E = 4 kV/mm occurs at a higher temperature around 70 degrees C corresponding to the temperature with the maximum dielectric constant (T-m). In addition, the ECE was found to insignificantly change well above the Tm. The wide temperature range accompanied by high Delta T-ECE in La-doped PMN-0.12PT ferroelectric ceramic indicates the promising candidate for applications in cooling technologies. (C) 2017 Published by Elsevier B.V.