Rational Co-Doping of SrZrO₃ and BaTiO₃ in Bi_0.5Na_0.5TiO₃ for Extraordinary Energy Storage and Electrocaloric Performances

The modification of the microstructure and electrical behaviors, through rational designing the composition of co-dopants (SrZrO3 and BaTiO3) in a modified Bi0.5Na0.5TiO3-based ternary system, has been systematically investigated. The extraordinary and controllable energy storage (maximum Wrec ∼ 1.15 J/cm3 and Wrec/ΔE × 100% ∼ 1.92% J/(kV cm2)) and electrocaloric (the maximum |ΔT| ∼ 2.13 K and the electrocaloric coefficient |ΔT|/ΔE ∼ 0.36 × 10–6 K m/V) performances can be integrated into this system, which are higher than those of other Bi0.5Na0.5TiO3-based systems reported previously. Meanwhile, this ternary system shows good thermal stability over a wide temperature range from room temperature to 120 °C. It is found that the coexistence and competition of linearly dielectric SrZrO3 and ferroelectric BaTiO3 deliver the doping evolution of polar nanoregions and obviously reduce the remnant polarization as well as the coercive field, resulting in enhanced energy storage and electrocaloric responses. These findings make Bi0.5Na0.5TiO3-BaTiO3-SrZrO3 (BNT-BT-SZ) ceramics very promising candidates as multifunctional materials.