Novel 3-3-like heterostructure engineering enables BaTiO3-based ferroelectric ceramics with superior electrocaloric performance

For environmentally benign lead-free ferroelectric ceramics, the trait of temperature-dependent phase boundary renders ceramics with intrinsic temperature sensitivity, obstructing them toward practical applications. Recently, laminated composite ceramics were widely implemented to solve temperature instability. However, such 2-2 type structure exhibits inherent limitations on properties promotion. Given this, the present work proposes a novel strategy of 3-3-like heterostructure engineering to tackle the problem. Compared to the laminated counterpart, 3-3-like ceramic shows boosted dielectric, ferroelectric and strain properties. Significantly, its electrocaloric (EC) operating range is expanded from 18 to 49 °C, two-fold wider than the laminated one, while a large EC temperature change of 0.66 K@30 kV/cm is maintained, which shows great property advantages to that of state-of-art lead-free ceramics. The superior performance benefits from the relatively uniform field dispersion of 3-3-like heterogeneity. As a contrast, sharp interface divergence causes abnormal field distribution and phase destabilization in laminated structure, which undermines the electrical properties and limits temperature stability. This work offers a favorable strategy for designing high-performance lead-free materials with desirable temperature reliability.