Giant electrocaloric effect in BaTiO3-Bi(Mg1/2Ti1/2)O3 lead-free ferroelectric ceramics

The microstructure, dielectric property and electrocaloric effect were investigated in the lead-free (1-x) BaTiO3-x (BiMg1/2Ti1/2)O-3 ((1-x) BTex BMT, x = 0.0-0.05) ferroelectric ceramics. Under the low electric field (E <= 20 kV cm(-1)), the coexistence of a positive and negative electrocaloric effect was obtained in (1-x)BT-x BMT (x <= 0.04) ceramics system using the Maxwell relation. Negative electrocaloric behavior disappears and the positive electrocaloric effect was only observed at high electric field (E >= 25 kV cm(-1)). Firstly, the values of both negative electrocaloric effect under low electric field of E <= 20 kV cm(-1) (NECE) and positive electrocaloric effect in the high electric field of E >= 25 kV cm(-1) (PECE) increase, then decrease with increasing BMT content in the ceramics. The 0.98BT-0.02BMT ceramic shows the excellent PECE and NECE capabilities. The corresponding giant electrocaloric effect values of -0.37 K (42 degrees C) at 20 kV cm(-1) and 1.21 K (143 degrees C) at 55 kV cm(-1) were observed. These results show great potential in achieving large cooling power as refrigerants. (c) 2018 Elsevier B.V. All rights reserved.