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(Mg 1/3 Nb 2/3 )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. Dual–peak effect was observed in the ΔT 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 °C at low electric field, and the second ECE maxima with ΔT ECE of 0.44 °C at E = 4 kV/mm occurs at a higher temperature around 70 °C corresponding to the temperature with the maximum dielectric constant (T m ). In addition, the ECE was found to insignificantly change well above the T m . The wide temperature range accompanied by high ΔT ECE in La–doped PMN–0.12PT ferroelectric ceramic indicates the promising candidate for applications in cooling technologies.