Electrocaloric refrigeration capacity in BNT-based ferroelectrics benefiting from low depolarization temperature and high breakdown electric field

Abstract

The development of an efficient electrocaloric (EC) material for refrigeration is of extreme importance for microelectronic and integrated electronic areas. No-lead-footprint 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ (BNT–BT) accompanied with a depolarization temperature (T_d) and impressive ferroelectric property emerges as a potential material for EC cooling. However, its long-term room-temperature EC behavior has been restricted by its relatively low breakdown electric field (E_b) and high T_d. This study reports that simultaneous Zr addition and AlN doping in BNT–BT (BNT–BZ_xT: yAlN) leads to a significant decrease of T_d and enhancement of E_b. Satisfying EC performances (temperature change ΔT of 3.2 K and EC strength ΔT/ΔE of 0.32 K mm kV⁻¹) close to the room temperature are realized with the composition of x = 0.2 and y = 0.2 wt% (BNT–BZ_0.2T: 0.2 wt%). Such excellent EC behaviors surpass most reported no-lead ceramics, which are even superior to 0.9Pb(Mg_1/3Nb_2/3)O₃–0.1PbTiO₃ ceramics. Most important of all, the present study offers an avenue for developing no-lead ceramics with an excellent room temperature ΔT towards solid-state cooling.