High Energy-Storage Performance and Superior Stability in Novel (Na _0.5 Bi _0.5 )TiO ₃ -Based Relaxor Ferroelectric Ceramics by Regulating Structural Distortion and Tolerance Factor Parameters

Simultaneously achieving a high recoverable energy density ( W rec ) and efficiency (η) in dielectric ceramic capacitors is crucial for advancing energy storage applications. Herein, a design strategy is adopted that involves regulating the parameters of structure distortion (δ) and tolerance factor ( t ) in (Na 0.5 Bi 0.5 )TiO 3 (BNT)-based relaxor ferroelectric ceramics. Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT) is doped into the BNT matrix to maintain a large δ and enhance maximum polarization ( P max ), while BaZrO 3 (BZ) is introduced to tune the t value close to unity, thereby improving η. To validate this strategy, (1– x )(0.75Na 0.5 Bi 0.5 TiO 3 -0.25Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 )- x BaZrO 3 (BNT-BCZT- x BZ) ceramics are fabricated and characterized. The optimized BNT-BCZT-0.15BZ sample exhibits excellent energy storage performance with an ultrahigh W rec (∼10.31 J/cm 3 ) and a high η (∼80.4%). Comprehensive structural and microstructural characterizations reveal that the multielement substitutions at both A- and B-sites result in the miniaturization of ferroelectric domains and form highly dynamic polar nanoregions (PNRs), which are crucial for the enhanced performance. Furthermore, the optimal ceramic demonstrates excellent frequency and temperature stability along with a fast charge–discharge speed ( t 0.9 ∼ 33 ns) and a high power density (∼391.9 MW cm –3 ). This work provides new perspectives for the development of dielectric energy storage materials.