Excellent energy storage and discharge performances in Na1/2Bi1/2TiO3-based ergodic relaxors by enlarging the [AO12] cages

Abstract

In this work, a lead-free 0.86(0.93Na_1/2Bi_1/2TiO₃-0.07BaTiO₃)-0.14K_1/2Bi_1/2(Zn_1/3Nb_2/3)O₃ (KBZN14) ergodic relaxor demonstrates excellent energy storage performance: W_s = 6.48 J cm⁻³, W_r = 5.10 J cm⁻³, and η = 80% at a moderate field of 29.0 kV mm⁻¹, accompanied by an outstanding frequency and temperature stability as well as a fast discharge rate t_0.9 of 69–79 ns. The excellent energy storage performance of the sample KBZN14 originates from the synergic effect of KBZN introduction: the enlargement of the [AO₁₂] cages of the pseudocubic perovskite host to facilitate the local polarization, and the complex cations (Zn_1/3Nb_2/3)⁴⁺ destroy the long-range correlations to percolate the polar nanoregions (PNRs) to room temperature. Our work provides a way to design NBT-based materials as a candidate for high energy density and pulse capacitor applications.