Near-Room-Temperature Large Electrocaloric Effect In Barium Titanate Single Crystal Based On The Electric Field-Temperature Phase Diagram

Phase transition plays a key role in the electrocaloric effect, but the first-order ferroelectric-paraelectric phase transition always occurs far above room temperature, which heavily limits the practical application. Herein, the focus is on the orthorhombic-tetragonal first-order ferroelectric-ferroelectric phase transition (@288 K) in -oriented barium titanate single crystal. Ferroelectric properties under a high electric field indicate a reversible field-induced tetragonal-orthorhombic phase transition, based on which the electric field-temperature phase diagram is established. It is strongly related to the enhanced electrocaloric effect, and a large adiabatic temperature change of 1.33 K is obtained at 288 K under 15 kV cm(-1), that is, a high electrocaloric strength of 88.7 mK cm kV(-1). The large electrocaloric effect near room temperature makes lead-free BaTiO3 a promising candidate for next-generation solid-state refrigeration.