Multiscale-engineered ferroelectric ceramics exhibiting superior electrocaloric performance

Electrocaloric effect referring to reversible temperature change (ΔT) under electrical excitation provides a promising alternative for next-generation thermal management. The ΔT essentially derives from the polarization change of polar system. However, conventional engineering hardly synchronizes large and flexible polarization change, so that large ΔT and high electrocaloric strength cannot realize concurrently. Herein, we propose a novel design strategy of multiscale engineering to boost the polar entropy of system, by which the large and flexible polarization change can be offered synchronously, availing large ΔT under a low driving field. The envision is validated in a heterogeneous Ba(Ti_1-xSn_x)O₃ system, where the different Ba(Ti_1-xSn_x)O₃ granules are mixed to enhance polarization heterogeneity of system. A large ΔT of 1.5 K and a high electrocaloric strength of 0.375 K mm kV^-¹ are achieved under a low driving field of 40 kV cm^-¹. Meanwhile, the substantial ΔT of more than 1.2 K is maintained within 30-50 °C. Our strategy provides a new paradigm for engineering electrocaloric material properties and can be expected for the design of other high-performance ferroelectrics.